Michael Screen

THE CROWOOD PRESS

First published in 2018 by
The Crowood Press Ltd
Ramsbury, Marlborough
Wiltshire SN8 2HR

www.crowood.com

This e-book first published in 2018

© Michael Screen 2018

All rights reserved. This e-book is copyright material and must not be copied, reproduced, transferred, distributed, leased, licensed or publicly performed or used in any way except as specifically permitted in writing by the publishers, as allowed under the terms and conditions under which it was purchased or as strictly permitted by applicable copyright law. Any unauthorised distribution or use of thistext may be a direct infringement of the author’s and publisher’s rights, and those responsible may be liable in law accordingly.

British Library Cataloguing-in-Publication Data

A catalogue record for this book is available from the British Library.

ISBN 978 1 78500 512 1

Acknowledgements

I would like to give my sincerest thanks to my partner Isabelle for her invaluable help and encouragement in editing and preparing the text for submission. I would also like to thank her father Paul for his photography and exceptional Photoshop skills. Finally, I would like to thank the countless students, both young and old, who have unwittingly served as my toy-making guinea pigs over the years.

INTRODUCTION

Are you looking to develop your ambition as a toy maker and craftsperson? You may be an aspirational hobbyist, semi-retired or retired, an educator, a practising craftsperson or a student looking for inspiration: this book shares some of my skills and experiences as an educator, toymaker and craftsperson of over thirty years.

What could be more satisfying than designing and building your own mechanical timber toys? They make amazing gifts both for children and for not-so-young family members. Your playthings will be given a name, and will be cherished, played with, and hopefully passed to a new generation. They will develop the endearing patination of age and use as they progress through their lifetime.

Perhaps you lack the confidence to currently develop your own mechanical toy ideas, or are looking for a challenge to produce more sophisticated examples. Mechanical toys are the perfect synthesis between craftsmanship, engineering and artistic expression. You have a plaything with its own beautiful mechanical action, and sounds that don’t need batteries or mains electricity to make them function. It is always fascinating to watch the input motion being converted into walks, wiggles, shakes, snaps, rattles and rolls. People love to examine them, to try and unravel the mystery of what is essentially a simple piece of wooden engineering.

The toy maker has a considerable repertoire of techniques and materials at their disposal for generating movement and character in a plaything. Many materials and processes are available, as even a glancing look at historical toy making will show. People have always used the indigenous materials and skills available to them, generating a rich and varied range of toys from different times across the world.

This book focuses on the production of five kinetic wheeled toys operated by a push-and-pull action, with timber as the primary construction material. They are not, strictly speaking, automata, which tend to be remotely operated with a more complex mechanism and generally operated by a hand-turned crank. The projects in this book use wheels, cams, cranks and linkages in various combinations to generate some beautiful mechanical actions when the toy is pushed and pulled.

Mechanical toys require only small amounts of material, such as offcuts and recycled timber, and can be produced in a relatively small space. You will also find in this book information on surface finishes, techniques and treatments to make your toys look amazing. This book will give you clear, concise, step-by-step instructions to produce five practical, kinetic toy projects, shown within these covers. Each chapter is filled with detailed step-by-step illustrated guidelines to produce a well made, functioning outcome. The book also contains advice and strategies to help you develop your own confidence and creativity. The only prerequisites to developing your toy making are access to rudimentary tools, and a workspace with a stable, secure worktop and vice.

Finally, timber toy craft production also offers an ethical and aesthetic antidote to the ruthless blandness and banality of many modern, massproduced, injection-moulded plastic toys.

CHAPTER ONE

TIMBERS AND MANUFACTURED BOARDS

Hardwoods and Softwoods

There is a bewildering range of timbers available to the craftsperson, each with its own unique physical and mechanical properties, which make it suited to any given application. It’s tempting to launch into a dry, arid, academic description of timber as a construction material, but for the purposes of this book you need only know several basic facts. First, timbers are classified as either ‘softwoods’ or ‘hardwoods’ – which can be confusing as some softwoods are hard, and conversely some hardwoods are soft.

The term ‘hard’ and ‘soft’ refers to whether the source of the timber is from a deciduous tree or a conifer, and isn’t necessarily a description of an individual timber’s physical properties. Hardwoods come from deciduous trees, which are slow-growing trees that lose their broad, papery leaves and become dormant in the winter months. Conifers are the ‘evergreens’ with waxy, spiny, spiky leaves which do not lose their leaves and tend to grow much faster. Conifers are classed as softwoods, and include the ‘pine’, which is a broad, generic term for a number of different conifers. All trees produce an annual growth ring, which indicates the quantity of timber produced radially within the trunk during the growth season. Hardwoods tend to produce a narrow, denser growth ring than conifers.

Deciduous trees – hardwoods – include species such as oak, ash, elm and beech, and the tropical hardwoods such as Sapele, mahogany and teak. Largely because of their slow growth, the wood fibres that are produced in the seasonal growth rings are more compact, leading to a timber of greater density. The relatively rapid growth of conifers produces wider, more fibrous growth rings and less dense timber. It’s worth remembering that balsa wood comes from a deciduous tree and is technically a hardwood even though it’s very soft. Conversely parana pine, which is very similar to a conifer, is very hard and durable.

Timber’s Physical Properties

All timbers have their own characteristics, ranging from elasticity, durability, density and ease of working, to name but a few. Some timbers, such as oak and beech, are heavy, hard, dense and difficult to work; they blunt tools easily, but are very durable, meaning they withstand atmospheric corrosion and abrasion well. Some timbers, especially tropical hardwoods, contain their own water repellent and insecticide, making them difficult to glue and giving the occasional unfortunate machinist respiratory problems and a nasty skin rash.

Grain structure and direction also offer some of the key characteristics of timbers. For practical purposes, a straight, knot-free timber often offers the best working and construction properties. People have always prized the beautiful figuring and grain patterns of timbers, and sometimes appearance trumps practical considerations for the most attractive and enduring timber objects.

The Conversion and Drying Process

All timbers are subject to the conversion process, which means felling the tree and carefully removing most of the water. Without this process the timber will shrink and dry out unevenly, causing splits and other defects, including fungal infections such as dry or wet rot.

The tree trunk is sawn longitudinally to form slabs, and then placed in a special kiln where moisture loss is carefully controlled, often over a long period of time. Hardwoods take much longer to grow, and require much more careful conversion and drying compared to conifers, which accounts for their higher cost.

Softwoods/conifers are ‘farmed’ commercially in managed forests, and the drying process is accelerated, leading to timbers that can shrink and distort too easily. It’s worth remembering that all timber is always ‘on the move’. This means that wood will shrink and stretch slightly in different temperatures and especially humidity, which is infuriating if you have just built a door, drawer or toy component that fits like a piston, only to discover a little later that it has shrunk by five millimetres or jammed shut! The rule to remember is that wood shrinks or stretches in width, never in length: it always shrinks or stretches across the grain.

It’s worth investigating the properties of timber further, as this will explain a lot about why certain timbers are used for specific purposes, and how they have been used through history. Elm, for example, is an indigenous hardwood with good water-repellent properties used for chair seats, tables and components for boat building. The final factor to consider is availability.

Conifers are easily and readily available in any number of builders’ merchants and DIY stores. They are machined and sold in preferred sizes or specific sectional dimensions and lengths. Softwoods are sold as unplaned, PBS (planed both sides), or PAR (planed all round), which makes marking out a lot easier since you start with at least one true edge and at least two right angles to work from. Much softwood available in these places is European white wood, the softest and most anaemic timber available used for general construction. It is often poorly seasoned, distorted, full of knots (the roots of a branch) and poorly grained. The next stage up is redwood, which is denser and has a pinky/ yellowy colour graining used for better quality construction. The best examples are straight grained, knot free and well seasoned, for which you pay a premium.

Hardwoods are available from specialist timber suppliers and saw mills. They are sold by the cubic foot as raw, seasoned slabs. You need the means to mill and process large pieces of timber if you use these suppliers, though you can often get small pieces for next to nothing. One common feature of many of these suppliers is their occasional and inexplicable indifference, rudeness or lack of cooperation if you exhibit any confusion or ambiguity about what you want. Similarly, I have encountered enormous generosity and selflessness from some yard assistants and sales people. The general rule of thumb is to do some homework and know what you want and roughly how much. Mentioning a few key, esoteric technical terms or words and phrases is akin to gaining access to the Masonic Lodge, and will open the portal to what you require without being ignored or belittled initially.

Finally, the most satisfying, ethically sound and least stressful source of raw material is recycling. Timber toys require little material, which is readily available from broken-up pieces of furniture (just don’t break it up without explicit permission!). Recycled timber is free, well seasoned and often machined to at least roughly the correct dimensions. You can visit the local refuse dump – or ‘recycling facility’, to use the correct term – where the staff often have a local racket going, whereby you can remove, or buy for a haggled fee, items that have been dumped. Beware, some of the staff exhibit the same characteristics as timber-yard staff and need to be handled carefully – so if you shake hands with some of them, count your fingers afterwards!

Timber Structure

Finally, timbers can be worked in two different directions. The first is longitudinally, or with/ along the grain. Wood fibres generally run parallel with each other, making cutting fairly straightforward and easy. The second is cutting across the grain, or at right angles to the grain direction, which is difficult, requiring great care not to split the wood. Wood is structurally stronger with the grain, and weak across the grain. It is important to plan components not to have areas ‘short across the grain’, as this will lead to splitting and snapping. The plans in this book direct you to lay out your templates carefully in order to take advantage of the structural strength of the timber being used.

Diagram showing timber grain structure, and an example of a component that has cracked due to being too thin and exposing too much end grain. This is known as ‘shortness across the grain’.

Timbers for Toy Making

Redwood: A dense, heavy and better quality conifer. The best redwood is straight grained, knot free and well seasoned. It is a pale, salmon pink/yellow colour, and is used for higher quality joinery. Redwood is a good quality, attractive timber, and a more ethical/economical alternative to hardwoods/deciduous timbers.

Oak: A dense, heavy and open-grained timber. It is very hard, making it difficult to work and shape without sharp, well maintained tools. Oak is very durable, making it ideal for furniture and outdoor structures. It reacts with ferrous metals, which cause a black stain to appear in the timber, so brass fastenings and fittings must be used. It is relatively inexpensive.

Beech: A dense, heavy, hard and straight-/ close-grained timber with few knots. It is very durable, takes stains and dyes well, and is used for toy making, furniture, frame works, tool handles, work benches, and components exposed to a great deal of abrasion and impact. It is expensive but easily available.

Lime wood: A light, close-/straight-grained timber with few knots. It is ideal for carving and pattern/mould making. It takes detail really well. It is easy to machine and shape with hand tools, with little splintering or splitting. It is relatively inexpensive and easily available.

Sapele: A tropical hardwood often confused with mahogany. It is reddish brown in colour, slightly oily, heavy, dense, hard and splintery. It can be difficult to work across the grain without splitting. It is used for high quality joinery and furniture. It is expensive and becoming rarer.

Manufactured Boards

Manufactured boards are an engineered solution to counter the defects and faults of natural timber, most notably its weakness across the grain, and its tendency to shrink, stretch and distort; it is also the solution to making a broad, flat, wide and smooth surface. Manufactured boards are available in thicknesses of 4mm, 6mm, 9mm, 12mm, 18mm and 22mm thicknesses. The following are examples of manufactured board materials, and their qualities that are suitable for toy making.

Plywood is constructed from a number of veneers or thin layers of timber. Each layer is bonded, with its grain direction at a right angle to the layer below. This counteracts timber’s natural tendency to shrink, stretch and distort. It resolves the grain direction problem and allows for the production of much wider, broader and flatter boards. Birch plywood is a fantastic manufactured board for toy makers as it is dense, heavy and attractive, and does not splinter excessively like Far Eastern plywood.

Far Eastern plywood: Made from veneers of tropical timbers such as Sapele. It is heavy, hard, dense and very splintery. It blunts tools quickly, and it can be difficult to get smooth, safe edges. Marine plywood is a similar, superior quality plywood product. It is available in thicknesses of 4mm, 6mm, 9mm, 12mm, 18mm and 22mm.

Birch plywood: This plywood is made from veneers of birch timber. It is very heavy, hard and dense, and is much less splintery than Far Eastern plywood. It can be very attractive, it finishes and machines well, and is much more durable than Far Eastern plywood. It blunts tools easily. It is available in thicknesses of 4mm, 6mm, 9mm, 12mm, 18mm and 22mm. It is expensive, but is very durable and stable, and takes staining and colour really well. It is the ‘go to’ material for toy making.

Medium Density Fibreboard: This board is made from wood fibres bonded together to form a heavy, hard, dense and smooth-surfaced timber product. It must be sealed very carefully and thoroughly to prevent moisture penetration and distortion. It takes a painted finish really well. It is available in thicknesses of 4mm, 6mm, 9mm, 12mm, 18mm and 22mm. It is useless if constantly exposed to moisture, and for making toy components exposed to abrasion, or if high dimensional accuracy is needed. MDF becomes flaky and fluffy without careful surface finishing and sealing. It is much more useful for modelling, and for testing mechanisms for toy ideas.

CHAPTER TWO

TOOLS AND MACHINES

It is beyond the scope of this book to give an exhaustive list of tools and processes and how to use them. I am assuming you have at least a rudimentary understanding of these, so I will itemize the essentials for the successful toy maker/craftsperson and their workspace.

• Organize your workspace to utilize it efficiently and to make it safe to work in. Keep the floor clear to avoid tripping, and place things away carefully to avoid the enormous frustration caused by losing or misplacing items

• Ideally you should have access to good natural or artificial lighting

• Learn how to look after your tools! Blunt tools are the most dangerous, besides causing mistakes in your work

• Power tools such as electric routers are a fantastic resource but require careful practice and use. A razor-sharp cutting tool rotating at 30,000 RPM is a formidable opponent when used incorrectly. Routers are second only to the angle grinder for hospitalizing craftspeople and construction workers

• Dust extraction and protection are important if you plan on doing a lot of work. It’s staggering how much wood dust accumulates in a short space of time, especially when using power sanding tools. At least wear a face mask or respirator

• The most basic need when working materials to form any object is being able to hold components safely and securely. Toy making offers the opportunity of working on a relatively small scale but requires some careful shaping and fitting, which can prove difficult without a sturdy vice. My advice would be to get a small, used workbench with a vice, and ideally a portable engineer’s vice (the type used for holding metal components)

• Go back to basics! Be able to work to a line using saws, planes and files. With one flat surface you have a datum point from which to make right angles and the three other, square, true edges and surfaces. This is especially useful when buying slabs of raw hardwoods and no access to a planer thicknesser or a table saw. With confidence you can be much freer and more intuitive by sculpting and shaping in a more expressive way using chisels, drum sanders and rotary cutting tools. The projects within this book make extensive use of drum sanders and rotary cutting tools, which need some practice to develop confidence. A useful idea is to try out techniques on a piece of scrap material first

• All cutting, abrasion and shaping hand tools have their electric equivalent, but it is good to be able to do things the low-tech way before ‘going electric’. The bottom line is that power tools cut out a lot of drudgery, speed up production and ensure dimensional accuracy (if done correctly). As a hobbyist, it can be very satisfying to cut and square up a timber blank occasionally before forming a component, but the repetition can be mind numbing

• Complete fabricating and assembly tasks in the correct order. It’s extremely difficult to locate and drill a hole accurately in an irregularly shaped piece of timber. Drill all holes while the workpiece is flat and easy to hold. Similarly, perform the shaping and fitting stages for projects explained in this book in the correct order to avoid complicating tasks unnecessarily. Each project is supplied with a page of templates which can be pasted on to the timber blanks to avoid complex marking out. Where a hole is required, refer to the required drill-bit diameter and centre punch the location to assist the drill bit to locate the hole accurately. Another example is drilling the holes for axles while the wheel blank is a square, and therefore easier to grip in a machine vice.

Useful Power Tools

All power tools are available in a number of sizes and power ratings. As a general guide, the higher the motor wattage, the more torque the motor will generate. This will allow faster working and ultimately prolong the motor’s life. Cheap, small wattage motors burn out too easily and quickly. The best for the workshop are those that can be bench mounted for the sake of portability and using a limited space effectively. Bigger, freestanding versions are available depending on your budget and workshop size.

The key to acquiring useful tools is to let need direct your purchases. As mentioned above, aim to buy the most powerful wattage, good quality motors, as these will give the tool greater torque and resist burning out. If you are a real purist, continue with hand tools exclusively. Finally, nothing compares to buying tools and machines with money you have made selling your own toys or crafts.

For toy making for the hobbyist with limited space and budget, the following machines are invaluable.

Bench-mounted pillar drill: A number of good models of pillar drill exist at a very reasonable price. Really cheap power tools have poor quality motors, which will burn out with excessive use. The pillar drill also allows a drum sander to be fitted, which is a very efficient abrasive tool.

Bench-mounted bandsaw: The bandsaw is ideal for cutting across the grain or for ripping work (cutting with the grain) if required. You need several blades for different tasks when using the bandsaw.

Scroll saw: Again, this can be bench mounted and enables the operator to cut extremely tight, curved profiles that require little surface finishing afterwards. Unlike the bandsaw, the scroll saw blade leaves few blade marks and doesn’t tear the wood fibre – a component cut with a fine scroll-saw blade needs almost no filing or glass papering. As with bandsaw blades, different grades of coarseness can be used for cutting different materials and thicknesses.

Orbital sander or linisher: These tools are fantastic for sanding angles and chamfers, and can be used with a number of jigs to produce different diameter wheels with the appropriate production jig. They are also criminally neglected as the source of many workshop accidents. An 80-grit abrasive paper will strip your finger tips and knuckles in an instant. Look for ones with a guard, feed the workpiece to the abrasive surface in the right direction, and don’t use too much pressure on the workpiece.

Rotary cutting tools: Several manufacturers offer these tools, with a bewildering range of cutting tools and attachments for a range of materials. It is the most versatile and enjoyable tool to use. The best models are sold with variable speed settings.

Electric router: There isn’t much an experienced router user cannot do with this machine, but as mentioned earlier, get to know it and practise safely before letting loose with it. I have a dedicated router set into a portable table to act as a mini spindle moulder. I once fed the workpiece in the wrong direction, causing the wooden piece to be propelled at high speed across the room before embedding itself into the plasterboard wall.

Wood lathe: This lathe is a fantastic resource if you can stretch to it. You can get very good quality, bench-mounted wood lathes for a reasonable price. A wood lathe can be used extensively for both toy-making and furniturebuilding projects.

The timber penguin toys were made on a wood lathe, cut and reassembled to make them more asymmetrical and lifelike.

CHAPTER THREE

BASIC MOTION AND MECHANISMS

Put simply, a mechanism is a movement and force processor. It converts one type or direction of motion or force into another, and can amplify or reduce it, and transmit it to where it is needed. Assembled into a system, a collection of different mechanisms becomes a machine. All mechanisms and machines process movement and force. There are four types or unique directions of movement – linear, reciprocating, rotary and oscillating – and all mechanisms and mechanical systems process these directions or combinations of motion and force.

Linear: Movement in a line.

Reciprocating: Backwards and forwards, or up-and-down movement.

Rotary: Movement in a circle.

Oscillating: Movement like a clock pendulum or see-saw.

Examples of movement types and directions. As a toy designer it is good to have a basic understanding of mechanisms and motion, especially levers, linkages and cam mechanisms.

Types of Mechanism

A lever is the simplest mechanism used to transfer or process motion and force. The three classes or types of lever all have a pivot point (or fulcrum), a load and an effort. There are three types or classes of lever.

Examples of lever showing the three classes or orders of lever.

The robot arms are a class three lever that oscillates when driven by the rotary action of the wheel. The whole assembly is similar to a treadle linkage used to drive old-fashioned sewing machines or potters’ wheels.

Linkage Mechanism

A collection of levers assembled together is called a linkage. The head and neck of the dinosaur toy uses a linkage mechanism to generate the rise and fall of the head and the accompanying snapping action. Linkages are some of the most common and versatile mechanisms available to the toy maker.

Cam Mechanisms

A cam is really a wheel that moves eccentrically or is reshaped to cause a lever in contact with it to reciprocate or oscillate. The dog’s tail, robot head and dinosaur head in this book are controlled by eccentric cams. A cam normally causes a lever called a follower to reciprocate or oscillate. For the purposes of toy making, gravity causes the follower to return to its original position before the cycle starts again. A smoother action can be achieved by placing a compression spring over the follower to keep it in constant contact with the cam wheel.

There are several cam profiles available, the most useful for kinetic toy making being the eccentric cam, which is essentially a wheel where the geometric centre has been off set. The greater the distance of the pivot point of the cam from the wheel’s true centre, the greater the possible lift it can generate.

Examples of cam wheels showing different profiles to generate different output motions.

The robot toy’s head reciprocates as it rises and falls on the eccentric cam connected to the wheel and axle assembly. Gravity causes the follower attached to the head to remain in constant contact with the eccentric cam without the need for any return springs.

Belt and Pulley

A belt is set within grooves between the drive wheel and the driven wheel. Speed changes between input and output speed can be achieved by changing the ratio of the driver to the driven pulley-wheel diameters. A driven pulley can also be caused to rotate in the opposite direction by twisting the belt in the middle.

A belt and pulley assembly driven by a small hand crank.

Chain and Sprocket

Toothed wheels or sprockets are driven by an articulated chain in place which works like the belt in a pulley and belt system. Its advantage is a greater reduction in slippage or the belt riding off. Small chain and sprocket kits can be purchased from craft and educational suppliers quite easily and cheaply.

The toy maker can produce gear wheels using a laser cutter or by buying gearbox kits from craft and educational suppliers. Complex transmission changes can be achieved by carefully designing the ratio between driver and driven gears or input and output gears.

Gear Mechanisms

Gears are toothed wheels where the chain or drive belt is dispensed with, and is replaced by the teeth on the gear wheels meshing together to transmit motion and force. As with pulleys and sprockets, increases or decreases in rotary transmission speed can be achieved by meshing gear wheels of different diameter with corresponding numbers of teeth.

Pawl and Ratchet Mechanism

This type of mechanism is used in old-fashioned football rattles. It generates a lovely clattering, rattling sound when rotated, which may be ideal for some toy ideas. The only drawback is that the pawl can only rotate in one direction. The ratchet is really a gear wheel with its teeth raked backwards.

Pawl and ratchet mechanism.

Scotch Yoke Mechanism

The Scotch yoke is a really useful mechanism for toy makers; it is also known as a slotted link mechanism. It is basically a reciprocating motion mechanism, converting the linear motion of a slider into rotational motion, or vice versa. The piston, or other reciprocating part, is directly coupled to a sliding yoke with a slot that engages a pin on the rotating part. The Scotch yoke creates a reciprocating or oscillating output from a rotating handle or wheel, without the need for an additional connecting rod as a crank slider mechanism needs.

Example of the scotch yoke mechanism.

Useful Mechanisms for Toy Makers

Kinetic mechanical toys rely on a fairly basic range of mechanisms and methods of generating motion or movement, which can be modified by the toy maker. The mechanical principles described earlier can be modified and adapted to suit lots of exciting toy-making possibilities. For the purposes of this book, the most versatile, useful and successful are described here.

The Synchronized Offset Wheel and Axle

Both wheels behave like an eccentric cam rotating eccentrically around an axle. This method will generate a small lift and fall effect. The frog toy’s rear axle uses an offset wheel to cause the rear of the frog to bob up and down slightly, creating a more frog-like jumping effect. The wheels have to be synchronized to rise and fall at the same points.

The synchronized offset wheel and axle: the frog toy’s rear axle causes a slight lift and fall.

The Opposed Offset Wheel and Axle

The opposed offset wheel and axle is similar to the synchronized offset wheel, but the wheels are not synchronized to rise and fall together, creating a waddling effect. This is achieved by offsetting the axle at the highest and lowest points respectively on each wheel.

The duck toy uses the opposed offset wheel and axle effect to create the waddling action.

The Offset Drive Axle

The offset drive axle is similar to a Scotch yoke effect, and will convert a rotary to a reciprocating or oscillating motion to cause a component to rise and fall or move backwards and forwards with a slight oscillating motion. The wheels fit on a centred axle and pivot within the interior of your toy. An extra axle/pivot is used to drive a component backwards and forwards or up and down.

The offset drive axle can be used to make an output oscillate or reciprocate.

The Inside Wheel Pegs

An inside wheel peg is a small wooden peg in the inside of the drive wheel that flips a component up and down. Gravity returns the component to its original position until the second peg on the other wheel repeats the process. A lovely oscillating head action can be achieved by synchronizing the inside pegs to create a continuous rise and fall action. By synchronizing the location of the pegs, it is possible to get two ‘flips’ for every wheel and axle rotation. This is possibly the simplest, most satisfying and effective method of generating motion in a kinetic toy. The mechanism is almost hidden and looks amazing. You will need to add spacer components to your inside wheel and peg mechanism to prevent the pegs jamming and becoming trapped against the body of the toy.

The dog and crocodile toys in this book use the inside wheel peg technique to flip the head up and down. The head shape is basically a bell crank.

Example of how an outside wheel peg or pivot can be used to generate a walking action.

Outside Wheel Pegs and Pivot

The illusion of walking or running can be achieved by pivoting a component away from the wheel’s geometric centre to create a rotary to an oscillating or reciprocating motion. The dog, frog, crocodile and dinosaur use this technique to generate a walking action. You must make sure that the component is able to make a full revolution when attached to the drive wheel without striking the ground. Wooden pegs located on the outside of the wheels can be used to flip a component up and down, using gravity to cause the component to return to its original position for the cycle to begin again. Alternatively the component, such as an arm or leg, can be screwed or pegged to the exterior of the wheel to make a continuous rotary and oscillating action.

The Cam and Follower Mechanism

As mentioned previously, the cam mechanism can be used to turn a small rotary motion into a reciprocating or oscillating output. For the purposes of this book, the eccentric cam has been used. The follower is simply the vertically mounted component that sits in contact with the surface of the eccentric cam wheel. It reciprocates as the cam wheel rotates. Gravity causes the follower to return to its original position, though compression springs can also be used to maintain a smooth motion. It is vital that the follower is held carefully in place, and able to travel through its reciprocating cycle easily without jamming. A follower can also be mounted at a right-angle to the cam wheel and pivoted at one end, only to generate an oscillating output motion. Again, gravity will cause the follower to remain in contact with the cam wheel.

Examples of cam and follower mechanisms. The follower can be vertical, or mounted at a right-angle to the cam and axle. Two output actions can be generated by mounting two or more eccentric cams to one shaft.

Wheels in Contact or Engaged Wheels

When one wheel is placed in contact with another, the rotary motion can be transferred through ninety degrees, a bit like gear wheels but without the meshed teeth. It is also useful to use this method with two eccentric cams to cause a vertical output to oscillate at a right angle to the drive wheel. The engaged wheel technique needs sufficient surface traction between the wheels to work successfully.

The wheel in contact or engaged wheel transfers motion through ninety degrees and also changes the direction of the output motion.

Putting It All Together

The projects in this book use at least two types of the mechanical principles explained in this chapter. The real creativity and fun begins when you start to mix and match different mechanisms to make a more complex mechanical toy system. A good way to test and model a mechanical action is to use stiff card and brass paper fasteners. Modelling mechanisms and designing toys will be dealt with in a later chapter.

CHAPTER FOUR

TIPS AND TECHNIQUES

The tips and techniques described in the following section will help you produce the projects in this book more efficiently, happily and easily.

Using Templates and Stencils

Templates and stencils are used to transfer the contours of components on to the timber blanks. This book contains templates for the production of most parts for each of the five practical projects described. You can trace, photocopy and resize the templates to suit the size you want. Remember that all components must shrink and stretch to the same ratio. It is recommended that you photocopy the templates, cut them out and paste them on to the timber blanks with a glue stick. Avoid using PVA or watery adhesives as these will wrinkle the paper and are very difficult to remove. You could also mount each template on to card and use it as a template to trace around.

Glue-stick templates on to the timber to form the components. You can also make template profiles by gluing the paper profiles to thick card. Thinner components will require careful alignment of the grain direction to avoid weakness caused by being ‘short across the grain’.

Locating and Drilling Holes Accurately

Use a centre punch to locate each hole for drilling, and ideally use a wood drill bit (a twist drill with a spike on the end to locate the hole more accurately) for drilling. Forstner bits are also ideal for larger diameter, flat-bottomed holes. These are used to drill out the holes to hold the mounts for arms and legs on dinosaur and crocodile bodies.

The location and diameter for every hole that needs to be drilled is shown on the templates for each project. A wood drill bit is used to locate holes more accurately than standard twist drill bits. A forstner bit is used for drilling larger diameter, flat-bottomed holes.

Drilling the Holes for Handles

The holes for handles for the frog, dinosaur and robot toy are shown as a dashed line on the side profile template. The dashed line represents the centre of the hole’s location. Use a try-square to mount the workpiece vertically to get the correct angle.

Mount the workpiece in a machine vice with the dashed line representing the hole location for the handle mounted vertically. Check for true vertical using a try-square.

When gluing, don’t attempt to clamp too early as this only causes the newly lubricated timber surfaces to slip and slide. Apply an even layer of glue, and ‘rub’ the join to expel surplus glue and trapped air. Leave the glue to set for a few minutes and then clamp the components. Wipe away surplus glue as this will prevent the absorption of any subsequent stains and colour, leaving nasty white patches.

The drum sander and rotary cutting tools are possibly the most versatile and liberating power tools. Use them extensively if possible to sculpt and shape components for the toys in this book. Their advantage is their speed, also a shaping process that requires no blows from carving mallets and chisels, and for the most part, you can hold the workpiece in your hands as you work on it. Rasps, chisels and heavy-duty carving will subject small workpieces to stresses and trauma that risk breaking them before they get anywhere near the inevitable battering delivered by an exuberant child.

Use the following drum sander diameters to match the concave area that needs sanding: 13mm, 19mm, 25mm, 38mm and 50mm. The choice of diameter is dictated by the curvature and radius of the area to be sanded. Drum sanders fit in a pillar drill where even small wattage motors offer the torque needed to remove the required material easily. Drum sanders used with rotary cutting tools are the next choice for sculpting and shaping material. They are available in diameters of 12mm, 10mm and 6mm. In addition, the manufacturers of rotary cutting and shaping tools offer a big range of rasps and cutting tools.

There is another option, but not for the faint-hearted: tool companies sell a flexible drive shaft to be fitted in the chuck of a pillar drill. The business end of a flexible drive shaft looks like a conventional rotary cutting tool, but be warned, they provide a lot of torque and the risk of nearly breaking your wrist or getting your sweater caught in it. After ending up with my arm in a sling and the front of my sweater missing, I decided that flexible drive shafts were bad news. Finally, remember that without due care and attention the 80-grit abrasive paper on drum sanders will skin your knuckles and fingers.

Constructing a Hollow Form

The dinosaur and dog toy need an internal cavity to locate the levers and eccentric cam needed to generate the required movement. This toy project requires the assembly of three timber blanks to produce an interior cavity that will accommodate the eccentric cam and head lever. It is really important to locate the interior spacer components very accurately. To accomplish this, paste the appropriate template to the inside face of one of the exterior timber blanks. Use a bradawl or compass point to make a series of pin pricks to highlight the location of the perimeter and the location of the interior components. You should also drill all hole locations on one exterior blank only before glass papering away all the paper template.

Use a bradawl or compass point to make a series of pin pricks to highlight the perimeter and location of the interior spacer blocks.

The impression left by the bradawl or compass point can now be connected with a pencil to guide the accurate location of the interior spacer blocks needed to complete a hollow bodyshell. Before gluing on the second half of the body side, test that the levers and pivot point work correctly, and modify these with a chisel if necessary.

Glue into place the spacer blocks that create the cavity/housing for the lever and eccentric cam. Rub away the paper templates, and place the axles and dowels in ‘dry’ to test the mechanism.

Glue the second half of the bodyshell into place. Once dry, complete all axle holes and pivot points by running the appropriate sized drill bits through the previously drilled holes. This is essential to avoid the holes not lining up. The leg and arm mounts for the dinosaur and crocodile toy need to be enlarged with a forstner bit after an initial pilot has been made. A timber insert is glued in to provide a true, even surface upon which to mount the legs or arms.

Fitting Arm and Leg Levers to a Curved Surface

Some holes, such as the leg and arm mounts for the dinosaur and crocodile toy, need to be enlarged with a Forstner bit after an initial pilot hole has been made. The cavity is then plugged with an 18mm or 25mm dowel. This is to allow for a level, parallel, square surface upon which to mount arms and legs after the body shape of the toy has been sculpted and rounded over. The arms or legs must be completely parallel with the exterior of the wheel surface in order to run smoothly. This technique allows for a more sculpted and less ‘blocky’ toy form, while allowing the legs and wheels mechanism to move easily and evenly. The holes that require expansion and plugging must be drilled before the body shape is sculpted and rounded over! The locations and dimensions for the plugs needed will be given in the chapters dealing with each relevant project.

Making Wheels

Wheels can be produced in several ways or purchased from a craft supplier. If you have access to a sanding machine, you can make a simple jig to allow the production of different diameter wheels to a fairly high dimensional accuracy. The wheel blanks are located on the sanding jig and rotated by hand against the rotating sanding disc. The diameter of the timber blank is reduced incrementally until the required final diameter is achieved. Care needs to be taken to avoid sanding knuckles and finger tips.

A simple sanding jig can be produced that can be clamped to the bed of the orbital sander or similar. The proximity of the arm to the sanding disc determines the final diameter of the wheels produced. Each blank is rotated against the disc individually and reduced in diameter incrementally. The timber blank for the wheel fits over, and rotates on a 9mm dowel located at the end of the arm.

CHAPTER FIVE

PAINTS AND FINISHES

There is a bewildering range of paints and finishes available for a wide variety of materials and purposes. All paints and finishes perform two essential tasks: firstly, to seal and protect the surface of the material from atmospheric corrosion and damage; also timber is prone to shrinking and stretching and must be sealed to prevent distortion and the penetration of dirt, oil and grease. Their second task is to decorate and embellish. Colour is an aesthetic component especially important to toys and playthings. Colour should be thought of as a unique component in itself, to be used carefully. All paints and finishes have their own characteristics, which can look amazing if used correctly.

Timber toys need careful surface preparation before the application of any finish. After rough shaping, cross filing and draw filing, use an 80-grit glass paper followed by 120-grit, 240-grit and finally a 1,200-grit paper for a super-smooth surface. Be careful to glass paper in the direction of the grain. A useful technique is to glue glass paper to a board and rub the workpiece on it. Be careful to rotate the workpiece and change direction so that you do not rub it unevenly.

The paints and finishes available are itemized below, with a brief description of each one. As a toy maker, it is useful to have a good understanding of paints and finishes as a component. Keep in mind that timber has its own figuring and patination, which can be used expressively – it isn’t always necessary or desirable to suppress its natural appearance.

Types of Paints and Finishes

Emulsion Paint

Emulsion paint is a water-based paint based on an acrylic or vinyl resin medium. It is available in a matt, eggshell or gloss finish depending upon the quantity of medium used. It is used for interior timber decorating, and is available in a wide range of colours. It is water soluble.

Gloss Paint

Gloss paint is an oil- or polyurethane-based paint made for interior and exterior timberwork. Gloss paints require the careful application of a timber primer, an undercoat and several top coats to get the full decorative and protective qualities of a gloss paint. Gloss paints are soluble in white spirit/turpentine. They are difficult to use on small, toy like objects without leaving brush marks and paint runs/drips.

Enamel Paints

Enamel paint is another oil-based paint with a high gloss finish. It provides a very hard-wearing, glossy, non-porous surface that makes it ideal for toy making, children’s furniture and interior decoration. These paints cover well and apply easily and evenly. They are also available as spray paints, and can be used on plastics and metals. Use white spirit/turps as a solvent. Enamels are ideal for toy- and model-making purposes.

Cellulose Paints and Lacquers

Solvent-based paints are often found in spray cans, and dry a lot faster than other types of paint. There are non-spray types available, but these are hard to apply with brushes. These paints include fascinating finishes such as speckled and hammered. Solvent sprays can be very expensive, but give very good results on small projects. A cellulose-based solvent is needed for cleaning up. Good ventilation is compulsory as the vapours are very toxic and flammable.

Cellulose paint/varnish can be easily thinned for spraying, it dries quickly, and is hard wearing and durable. It used to be used for car bodies, but has largely been replaced by less dangerous acrylics and enamels. Cellulose thinners are used as a solvent. ‘Hammerite’ is a good example of a cellulose paint.

Cellulose paints and lacquers can be used on plastics and metals. Cellulose lacquer is a hard-wearing, clear finish that can be sprayed rapidly to seal the surface of your toys. Be careful you don’t spray it over other cellulose paints as it will cause the underlying layer to wrinkle and lift.

Polyurethane-Based Varnishes and Paints

Because of its polyurethane content, polyurethane paint is similar to liquid plastic when wet. Use this type of paint/varnish to protect interior and exterior timberwork from scratches and dents. Polyurethane paint/varnish comes in three types: water-based, oil-based and oilmodified water-based. It has a hard-wearing, durable but slightly plastic-looking surface.

Shellac Sealer/Button Polish

This sealer is used as part of the French polishing technique. It provides an excellent method of sealing timber before polishing with wax. It is also ideal to seal in dyed colour prior to waxing or varnishing. It is not very durable and can be easily damaged by water. Methylated spirits must be used as a solvent. Take care as both shellac sealer and meths are highly flammable.

Shellac sealer or sanding sealer is an excellent method of sealing a timber surface to prevent moisture swelling the wood fibres near the surface and causing the grain to raise. When dry, these fibres stick up and dry, leaving a horrible prickly surface. Timber toy components can be sealed with shellac after dyeing or colouring, and then given additional coats of polyurethane varnish or cellulose lacquer to make a more durable, hardwearing surface.

Wax and Oil Finishes

Wax and oil finishes can be applied over a dyed and shellac-sealed surface. They are ideal for polishing turned items and small decorative items. Wax is a good water repellent but leaves white stains when exposed to too much moisture, especially if used over shellac. Waxes can be natural or silicon based. Wax finishes are high maintenance and not very durable. Oil finishes are good for external timberwork, especially tropical hardwoods.

Water-Based Wood Dyes

Colour can be applied to timber by using wood dyes; these are easily available in DIY stores. Many wood dyes are water based, which causes the grain to raise, giving the timber an unpleasant fuzzy texture when dry. Spirit-based dyes avoid this problem, and can then be easily sealed with a suitable varnish. A water-based wood dye can easily be made from thinned acrylic paint or similar.

Spirit-Based Wood Dyes

Spirit-based wood dyes can be made by combining oil paints or edible food dyes and surgical spirit. A wide range of colours and tones can be achieved with experimentation. Spirit-based wood dyes do not raise the grain, and like water-based dyes are only a decoration without any protective qualities. The dyed timber needs to be sealed in with a suitable varnish. When dyeing timber, the rule to remember is that the colour begins light and can only ever be darkened. Experiment on scrap pieces of timber to see what is possible. Finally, wood dyeing is only generally effective on timbers that are already pale, such as beech or redwood.

Surface Treatments for External Timberwork

If you plan to produce toys for outside, the timber needs to be protected from moisture penetration, insect attack and fungal infection. Tanalizing is a treatment where the timber fibres are placed within a vacuum and then injected with an oil-based insecticide and water repellent. Timber can also be painted, sprayed or dip-coated using a variety of coloured preservatives. Some can be very toxic.

CHAPTER SIX

THE FANTASTIC FROG

The frog’s rear wheels and legs generate a slight jumping action and cause his big glum mouth to open and close as the toy is pushed along. He uses a simple, bell crank-type lever for a head, and class three levers for rear legs that pivot and rotate on the rear wheels. Both rear wheels are synchronized and mounted eccentrically on the rear axle. Every rotation of the rear wheels makes a slight bobbing action.

He is made from redwood, but you can choose whatever timber you like. Prepare all parts and use a spirit-based stain to make the green colour. The surface pattern decoration was made by spraying paint through a stencil made from MDF offcuts. Finally, polyurethane varnish was used to seal the surface of all components before assembly.

The completed frog toy.

To make the frog toy, prepare the following materials:

CUTTING LIST FOR THE FROG TOY

Part |  | L × W × T | Quantity | Material
Body blank | A | 150 × 130 × 20mm | 2 | Redwood
Head centre | B | 60 × 50 × 44mm | 1 | Redwood
Head sides | C | 90 × 80 × 10mm | 2 | Redwood
Wheels |  | 55 × 55 × 29mm | 4 | Redwood
Rear axle |  | 70 × 9mm dowel | 1 | 9mm dowel
Front axle |  | 70 × 9mm dowel | 1 | 9mm dowel
Upper legs (long) | D | 130 × 50 × 10mm | 2 | Redwood
Upper legs (short) | E | 110 × 50 × 10mm | 2 | Redwood
Lower legs | F | 130 × 50 × 10mm | 2 | Redwood
Handle |  | 400 × 18mm diameter dowel | 1 | 18mm dowel
Handle hand grip |  | 95 × 25mm diameter dowel | 1 | 25mm dowel
Eyes |  | 10mm diameter wooden beads approx. | 2 | Hardwood beads

FIXINGS NEEDED TO PRODUCE THE FROG TOY

Part | Fastening | Quantity
Jaw pivot | 10-gauge × 1in round-head, black Japanned screw | 2
Upper leg pivots (fixing the leg to the body) | 10-gauge × 1½in round-head, black Japanned screw | 2
‘Elbow’ pivot | M4 lock nut and 40mm pan-head screw with two M4 washers. (Screw/bolt head faces inwards to avoid jamming on the frog’s jaw) | 2
Wheel pivot | 10-gauge × 1in round-head, black Japanned screw | 2

Templates for the Frog Toy

The templates for the frog toy need to be expanded to fill an A3 size piece of paper. Enlarge the templates on a photocopier until the diameter of the wheel templates measures exactly 50mm.

Templates for the frog toy components need to be enlarged on to an A3 size page in order to get the correct scale and ratio of components. All locations and diameters for the holes to be drilled are shown in millimetres.

Constructing the Frog Toy

Step 1: Assembling the body

1. Photocopy and cut out the templates for the frog body (2 × part A). Shape and glue on to a 20mm thick piece of timber.

2. Use the first piece to trace around and make a second body shape. Glue the two frog body shapes together to form a 40mm thick body blank. Make sure the pasted template is clearly visible, and centre punch the location for all holes. Drill out the holes for the axles, head and leg pivots.

Step 2: Drilling the 12mm hole for a handle

Drill out a 12mm hole to a depth of 25mm in the back of the frog to receive a handle. Use the dashed line shown on the template to guide the position and angle of the timber body blank in a machine vice. Use a try-square to check for vertical. The timber body blank and machine vice must be completely parallel with the edges of the pillar drill bed or you will inadvertently drill a compound angle, which is useful for chair making but not frog push/pull handles.

The frog toy body blank must be mounted into a machine vice as shown to drill the hole for the handle at the correct angle.

Step 3: Assembling the components for the frog’s head

1. Paste the head centre (part B) on to a block of 44mm thick timber and carefully cut it out.

2. Make two head sides (part C) from 10mm thick timber, taking care to make sure the grain is located top to bottom to avoid splitting.

Cut out, clean up and assemble the components for the frog’s head, taking care to wipe away any surplus adhesive.

3. Clean up the concave areas of the head components with files, glass paper and drum sanders, and assemble them using PVA. Allow the glue to set slightly before clamping in a vice. Wipe away any surplus adhesive.

Step 4: Drilling the holes for the head

1. Centre punch the location of all holes needed.

2. Drill out the 5.5mm holes for the frog’s head pivot point. (Make sure to pack the cavity to prevent the wood splitting and cracking.) Drill all the way through from one side only.

3. Drill the 5mm location on each side of the head for the eyes, to a depth of 10mm. Countersink the location of each eye to receive a wooden bead later.

When you drill out the head pivot, make sure to pack the cavity between the head sides with scrap timber to prevent splitting.

Step 5: Fitting and testing the head and the frog’s body

1. Fit the head to the body. Pin it temporarily with a wood screw. Test that the head moves freely and easily, and adjust any tight spots with files and glass paper if necessary.

2. Use files, glass paper and drum sanders to clean up the edges and surfaces of your frog’s head and body.

3. Remove all traces of the paper template once drilling and test fitting are complete.

Finally, radius the edges of the frog’s body. You can do this with an electric router if available, otherwise use a rasp, files and glass paper.

Temporarily assemble the frog’s head and body and radius the edges, taking care they are not excessively round over the axle locations.

Step 6: Making the wheels and axles

1. Mark out four wheel blanks measuring 54 × 54 × 20mm.

2. Find the centre of each wheel blank by connecting the diagonals, and draw a 25mm radius circle on each wheel blank to form a circle of 50mm diameter. Repeat for both sides of the wheel blank.

3. Centre punch both front wheel centres before drilling. Drill both front wheel centres to a depth of 15mm using a 9mm diameter drill bit.

4. The rear wheels have the axle centre offset from the circumference by 20mm to create a frog-like hopping action. To achieve this, mark the axle centre 20mm from the circumference, and drill out a 9mm axle hole on each wheel, as described for the front wheels.

5. Flip the rear wheels over and drill a 2.5mm pilot hole for the legs to pivot on the rear wheel exteriors. The 2.5mm pilot hole must be directly opposite on the circumference to the location of the rear wheel axle location to make a convincing lift and fall action.

6. Remove the waste from the wheel blanks until they are completely circular. Use glass paper to radius the circumference edges of each wheel. Glass paper to finish, and dry assemble both axle assemblies to test for accuracy. Both rear wheel axle locations must be completely parallel with each other to make the lift and fall action, without any oscillating side to side, which would spoil the motion.

7. To find more helpful information on wheel making, refer to Chapter 4 ‘Tips and Techniques’.

Cut out and assemble the wheels and axles. Remember that the rear wheels turn eccentrically to generate the rise and fall motion at the back of the frog’s body.

Step 7: Assembling the wheels and axles, and cutting out the leg components

1. Make two axles measuring 75mm. Make a ‘dry fit’ assembly of the wheels, axles, head and body to test for accuracy.

2. Paste the templates for the leg components (parts D, E, and F). Cut out the leg components using a scroll saw, coping saw or a bandsaw.

3. Assemble the components for the upper legs (parts D and E). Make sure the spur projecting from part D is eventually flush with the frog’s body. Put part D over part E to form the upper leg. Clean up and drill out all the holes for the leg components.

Cut out all the leg components and drill out all the holes to the required diameter.

Carefully assemble and locate the upper leg so that the spur projecting from its edge will strike the frog’s jaw, causing it to lift and fall.

Step 8: Sculpting and shaping the frog’s head using drum sanders and rotary tools

1.Shape and sculpt the frog’s head using a combination of different diameter drum sanders and rotary cutting tools. Or, you can simply radius the edges of the frog’s head without any more complex shaping.

2. For the purposes of sculpting the head, begin with a 140mm radius, 80-grit drum sander to round over the head front, and then progress to a 10mm and 6mm 80-grit drum sander attached to a rotary cutting tool. The sequence for sculpting the frog’s head is shown in the accompanying illustrations.

3. Before beginning the shaping, countersink the eye cavities to receive a bead for an eye later.

Finally, round over the underside of the frog’s lower jaw shape to give it that glum, doublechin effect, and blend in the upper and lower jaw shaping.

Countersink the eye spacers to a depth of 10mm.

Use a 13mm drum sander to begin the gap between the frog’s bulbous eyes.

Round over the front of the frog’s head using a 140mm drum sander.

Round over the front of the head using a 140mm drum sander.

Use a 13mm drum sander to hollow the area below each eye.

To create the frog’s overbite lips and glum expression, use a 13mm drum sander to hollow the area above the front of the frog’s head.

Glass paper the head to remove all rough areas, and sculpt the lower jaw area on the frog’s body to ‘blend in’ the sculpting.

Fit the frog’s head to the body temporarily using a woodscrew and file, then sand, sculpt and shape both components together to ‘blend them in’.

Step 9: Assembling the legs and joining them to the body

1. Assemble a pair of upper leg assemblies (parts D and E). Attach a lower leg component (part F) to each upper leg assembly, as shown.

2. Fasten the lower leg to each upper leg assembly using a 40mm machine screw and M4 nylon lock nut. Take care not to overtighten the nut.

3. Fasten each leg assembly to the frog body using an 8-gauge × 1½in round head, black Japanned screw. For the sake of clarity, the examples shown are unpainted or decorated. (It is much better to decorate and seal each component before assembly.)

Assemble the lower legs to the upper legs, and fix to each side of the frog’s body. Make sure the spur that projects from the upper leg assembly is fitted flush to the side of the frog’s body.

Step 10: Fixing the legs to the wheels

1. ‘Dry fix’ both axles and wheel assemblies into place, and make sure the rear wheels are synchronized to rise and fall at the same time in order to create the hopping action.

2. Drill pilot holes on the exterior of the rear wheels to receive the frog’s lower leg (part F). Both pilot holes are 12mm from the circumference of each rear wheel and located opposite the rear wheel axle locations. Make sure the legs are synchronized to drive the head up and down simultaneously and maximize the lift and fall action.

3. Fasten the lower leg to the rear wheels as they reach their highest points during rotation. The pilot hole for each leg pivot should be located from the opposite circumference to the axle location.

Dry fit the wheels and axles into place, and mark out the location for the 2.5mm pilot holes to receive an 8-gauge × 1in round head, black Japanned screw to make the lower leg pivot against each wheel.

Step 11: Fitting a handle

1. Add a handle made from 400 × 12mm diameter dowel. The top of the handle can be fitted with a hand grip made from 95 × 25mm diameter dowel.

2. Centre punch the hand grip to receive a 12mm hole for fastening it to the handle.

Glue the handle grip to the handle using PVA. Test the assembled toy for accuracy and smooth movement. Use wax to lubricate any stiff areas.

Assemble the handle by adding a cross-piece to act as a hand grip, and secure it with pva and a 10-gauge 1¾in woodscrew.

Step 12: Finishing and decorating

1. The frog toy example has been stained with green vegetable-based food colouring suspended in a solution of surgical spirit. The process provides gorgeous hues and tones without obliterating the underlying wood grain. The method also allows coloration without raising the wood grain as water-based dyes will.

2. When dry, a pattern has been sprayed using enamel paint through a card stencil made from laser cutter offcuts. Make your own stencil by cutting shapes into carton board with a super-sharp scalpel. Apply the stain solution quite liberally with a brush, using a rag to wipe away any surplus solution. Each coat of stain will darken the hue according to the ratio of pigment to spirit.

3. It would be wise to experiment on scrap timber first – and remember that you can never lighten the hue. Paint the components as if you were working on a watercolour painting, where the golden rule is, always work from light tones or hues to dark. It will not work in reverse!

When the colouring and varnishing of individual components is complete, assemble the frog toy for the final time.

Applying the Finish and Decoration

1. Sand all components, beginning with an 80-grit glass paper, followed by 120-grit, 240-grit and finally a 1,200-grit.

2. Apply two or three coats of polyurethane varnish or cellulose lacquer. Rub down between the first two coats of varnish with 240-grit and the last, third coat with 1,200-grit.

3. When the third and final coat of varnish has dried completely, a layer of silicone or beeswax can be added to lubricate and reduce surface friction.

4. Paint the eyes yellow and add a vertical pupil to give the frog its froggy stare. Glue the eyes into place using a two-part epoxy adhesive.

The frog toy has been stained using a combination of edible food dye and surgical alcohol. Once stained and dried, a pattern was added by spraying enamel paint through a card stencil. Finally, the surface has been sealed with three coats of polyurethane varnish.

CHAPTER SEVEN

THE HUNGRY HOUND

The hound dog toy snoops, sniffs and yaps as he is pushed or pulled along. His legs generate a walking action, and the tail flips up and down, driven by an eccentric cam and follower hidden between the rear wheels. The head is basically a bell-type crank similar to the frog, but is flipped up and down by two inside wheel pegs located on the interior of each front wheel. He can be pushed with a handle just like the frog toy. The components for the hungry hound have been individually finished and decorated with enamel spray paint before assembly.

To make the dog toy, prepare the following materials:

The completed dog toy.

CUTTING LIST FOR THE DOG TOY

Part | Ref: | L × W × T | Quantity | Material
Body blank | A | 250 × 120 × 20mm | 2 | Redwood
Body blank centre | B | 250 × 120 × 20mm | 1 | Redwood
Head centre | C | 100 × 40 × 50mm | 1 | Redwood
Head sides | D | 120 × 65 × 10mm | 2 | Redwood
Eccentric cam | E | 35 × 35 × 20mm | 1 | Redwood
Wheel blanks |  | 55 × 55 × 20mm | 4 | Redwood
Front wheel axle spacers |  | 18 × 14mm dowel | 2 | Dowel
Rear wheel axle spacers |  | 18 × 5mm dowel | 2 | Dowel
Inside wheel pegs |  | 20 × 9mm dowel | 2 | 9mm dowel
Cam follower |  | 6mm diameter dowel × 25mm | 1 | 6mm dowel
Rear axle |  | 9mm diameter dowel × 85mm | 1 | 9mm dowel
Front axle |  | 9mm diameter dowel × 95mm | 1 | 9mm dowel
Pivot for wagging tail |  | 6mm diameter dowel × 60mm | 1 | 6mm dowel
Upper front legs | F | 80 × 50 × 20mm | 2 | Redwood
Lower front legs | G | 100 × 50 × 10mm | 2 | Redwood
Upper back legs | H | 100 × 50 × 10mm | 2 | Redwood
Lower back legs | I | 100 × 50 × 10mm | 2 | Redwood
Tail profile | J | 150 × 55 × 12mm | 1 | Birch plywood
Tail width extension | K | 70 × 25 × 9mm | 2 | Birch plywood
Handle |  | 400 × 18mm diameter dowel | 1 | 12mm dowel
Handle hand grip |  | 95 × 25mm diameter dowel | 1 | 25mm dowel
Front leg spacers |  | 18 × 14mm dowel | 2 | 18mm dowel
Rear leg spacers |  | 18 × 5mm dowel | 2 | 18mm dowel
Eyes |  | 6mm wooden beads | 2 |
Nose |  | 18mm or equivalent wooden bead | 1 |

FIXINGS NEEDED TO PRODUCE THE DOG TOY

Part | Fastening | Qty
Jaw pivot | 10-gauge × 1in round-head, black Japanned screw with M4 washer | 2
Upper leg pivots (fixing the leg to the body – front legs) | 8-gauge × 1¾in round-head screw | 2
Upper leg pivots (fixing the leg to the body – back legs) | 8-gauge × 1in round-head screw | 2
‘Elbow’ pivot | M4 lock nut and 25mm pan-head screw with two M4 washers. Screw/bolt head faces inwards to avoid jamming on the dog’s jaw | 2
Wheel pivot | 8-gauge × ¾in round-head, black Japanned screw with M4 washer | 2
Screw for fastening cam wheel to axle | 6-gauge × ¾in, countersunk-head woodscrew. Screw 1 | 1

Templates for the dog toy components. Enlarge the templates on a photocopier until the diameter of the wheel templates measures exactly 50mm. All locations and diameters for the holes to be drilled are shown in millimetres.

Templates for the Dog Toy

The templates for the dog toy need to be enlarged to A3 paper size. Enlarge the templates on a photocopier until the diameter of the wheel templates measures exactly 50mm.

Constructing the Dog Toy

Step 1: Forming the body components

1. Cut out the three components that form the dog’s body. Make sure the template for part A is pasted on the inside surface of one of the body sides. You will need to make two part As. Centre punch and drill out all the holes to the required diameter on one outside panel for the dog’s body.

2. Prepare the location for fitting the middle component to create the housing for the cam and follower (located above the rear axle and wheels). The technique for locating the centre/spacer component accurately is described in Chapter 4, in the section ‘Constructing a Hollow Form’.

Prepare the components for the dog’s body form. The completed form consists of three parts. The inside component creates the cam and follower housing to make the tail oscillate/wag.

Step 2: Forming the body spacer component

The centre component for the body (part B) has a blank area that forms the housing for the eccentric cam and follower to drive the tail. It will need a 6.5mm hole drilled carefully and accurately to house the cam follower. Mount the body centre component into a machine/ hand vice as shown, and check to get a true vertical using a try-square before drilling a hole that passes through all the paper template area.

The dashed line on component B (the body centre) is used to guide the 6.5mm drill through the area above the eccentric cam to allow a 6mm dowel follower to move easily and drive the tail up and down. Drill it out before you cut the exterior profile of the component.

Step 3: Assembling the body blank

1. Use a drum sander to clean up the concave areas of the body components, especially around the cam and follower housing, as these will be inaccessible once the body has been glued together.

2. Sand the template from part A before gluing and clamping the three body components together. When the glue has dried, drill all the holes for the axles and pivot points all the way through by guiding the drill bit through the holes previously drilled through part A.

3. Drill a 12mm hole to a depth of 30mm for the handle, using the dashed line on the template as a guide. Mount the glued-up body blank in the hand/machine vice with the dashed line projecting upwards. Use a try-square to check for a true vertical, and carefully centre punch the hole location.

The dog’s body is reduced in width to make it look less heavy and less ‘blocky’. The haunches are left wider to emphasize the stooped, snuffling action.

Glue and complete the drilling for the body blank by guiding the appropriate sized drill bits through the previously drilled holes on part A.

Step 4: Roughing out the body blank

Use a marking gauge and try-square to mark out the body blank to the dimensions shown. Use a bandsaw to cut away the waste areas, taking care to keep the body blank squarely on the bed of the bandsaw. It might be useful to make a series of straight cuts or kerfs at a right angle to the scribed lines to make removal of waste easier, as the bandsaw doesn’t need to pass through the tight curve at the end of the dog’s haunches.

Step 5: Shaping and finishing the body blank

Round over, sculpt and shape the dog’s body using a variety of drum sander diameters fitted to the pillar drill. Use the following diameters to match the concave area that needs sanding: 13mm, 19mm, 25mm, 38mm, 50mm and 140mm. The choice of diameter is dictated by the curvature and radius of the area to be sanded. For the bulk of waste removal, the 140mm diameter sander with an 80-grit paper will suffice.

Note: It is very important not to round over the points where the dog’s legs and head will fit/pivot, as this will make it difficult for them to move properly and will leave nasty gaps.

The finished form for the dog’s body is becoming recognizable, with the housing for the tail and eccentric cam becoming more defined. The area for housing the tail is clearly visible.

Glue the components for the head as shown. Line up the exterior contours of the front of the dog’s head to locate the centre piece accurately.

Step 6: Assembling the components for the head

Cut out two parts D (head sides) and one part C (head middle). Glue up the components to form the head blank. Leave the glue to set a little before clamping to avoid slipping.

Step 7: Drilling out the pivot point for the head and locating the position for the eyes and nose

1. Once dry, pack the cavity between the head halves with a piece of scrap timber before drilling a hole all the way through for the head pivot using a 5.5mm drill bit. The location for the head pivot point is shown on the template.

2. The eyes and nose can be located by using a try-square and marking gauge. The important thing is that the eyes are equi- distant from the edges, and that the nose is centred. With a 5.5mm drill bit, drill to a depth of 10mm for both eyes and nose.

3. Use a countersink bit to expand the holes for the eyes and nose to receive a wooden bead later. It is essential to complete all drilling and countersinking before sculpting and shaping the dog’s head.

Drill the head pivot all the way through using a 5.5mm drill bit. The location for the hole is shown on the paper template. Pack the cavity with scrap timber to prevent splitting.

Mark out the location for the dog’s eyes and nose as shown. Drill the 5.5mm holes to a depth of 10mm.

Step 8: Shaping the dog’s head

1. Use drum sanders to shape and sculpt the dog’s head. Begin by tapering the head from the back to the front to give the appearance of a canine snout. Round over the sides and edges of the head. Do not round over the underside of the dog’s jaw!

2. Eventually, a 10mm wooden bead can be used to form a nose and two 6mm beads for eyes. Glue the beads into place after staining, painting and sealing are complete.

3. The final addition to complete the dog’s head are ears made from leather or vinyl screwed to the sides of the head. After shaping, temporarily fix the head to the dog’s body, and glass paper them together.

A completed head form gives you a good guide for shaping and sculpting the dog’s head. The snout projects upwards and the sides are slightly concave.Let the drum sander diameter determine the required curvature.

Step 9: Making the wagging tail

1. Cut out part J from 12mm birch plywood. Drill a 7mm hole for the tail pivot point. Cut two K components, which form the sides of the top of the dog’s tail. Glue both K components on to the upper surfaces of part J, and leave to dry.

2. Use a 140mm drum sander to round over and taper the tail assembly to the form shown in the photograph.

3. Glue a packing piece of 18mm dowel or similar on each side of the dog’s tail, and roughly half way down it, to prevent it rocking excessively from side to side.

The tail is driven by an eccentric cam and follower concealed between the back axle and the rear end of the dog.

When dry, sculpt the dog’s tail with a 140mm drum sander, and then glass paper the completed form. Glue a packing piece on each side of the dog’s tail to prevent it jamming against the sides.

Step 10: Fitting the wagging tail

1. Peg the tail assembly into the 6mm pivot point located at the back of the dog’s body. Test it for free movement, and adjust as necessary. Fit the 6mm diameter × 25mm dowel cam follower into the cavity located above the cam housing.

2. Dry fit the 85 × 9mm rear axle, and thread the eccentric cam over until it fits centrally. You must make sure to trap the cam follower above it.

3. Dismantle the tail assembly ready for finishing and painting.

The cam follower housing is located above the cam housing between the rear axle. Temporarily screw the eccentric cam to the axle using a 6-gauge × ¾in, countersunk-head woodscrew. Make sure the axle protrudes the same distance from each side of the dog’s body. Fit and test the rear axle for smooth movement and to make sure the cam will make the tail oscillate easily.

Step 11: Making the wheels

1. Find the centre of each wheel blank by connecting the diagonals, and draw a 25mm radius circle on each wheel blank to form a circle of 50mm diameter. Repeat for both sides of the wheel blank. Centre punch both front wheel centres before drilling.

2. Drill both front wheel centres to a depth of 15mm using a 9mm diameter drill bit. Next drill a 9mm hole 10mm in from the circumference of both front wheels, and drill to a depth of 10mm to receive the inside wheel pegs used to flip the head up and down.

3. Turn the front wheels over and drill a 2.5mm pilot hole on the opposite side of the circumference to the inside wheel peg location. The 2.5mm pilot hole must be directly opposite to the location of the inside peg location in order to create the walking action. Each pair of front-leg assemblies will rotate/oscillate against the front of each pair of wheels once for every rotation of the front axle.

4. Repeat this process to produce the pilot holes for the location of the rear wheels. A ‘one up and one down’ configuration of the leg locations is essential to create the walking action.

5. Remove the waste from the wheel blanks until they are completely circular. Use glass paper to radius the circumference of each wheel. Glass paper to finish, and dry assemble both axle assemblies to test for accuracy. To find more helpful information on wheel making, refer to Chapter 4, ‘Useful Tips and Techniques’.

The front and rear wheel assembly, showing the 25mm-diameter axle-spacer blocks used on the front axle to prevent the inside pegs from jamming.

Step 12: Making the front and rear axles

1. Cut a 95mm length of 9mm diameter dowel for the front axle. Cut an 85mm length of 9mm dowel for the rear axle. All wheels are 50mm in diameter. Produce them in the same way as the wheels for the frog toy. The holes for both front and rear axles must be set to a depth of 15mm.

2. The front wheels have a 9mm inside peg set on the interior of each front wheel. Locate the position for the peg for each wheel by measuring 10mm from the circumference to the centre of the hole location for the peg. Remember, the front wheels will need to be synchronized eventually to cause a lift and fall for every rotation of the axle.

3. The rear axle is 85mm in length and made from 9mm diameter dowel. The rear axle requires two spacer blocks placed between the top of the upper rear legs and the dog’s body to project the leg assembly away from striking the dog’s side and jamming. The spacer also causes the lower part of the leg to line up parallel with the wheel exterior. Each spacer is cut from a 25mm diameter dowel to a width/length of 5mm. Drill a 5.5mm hole through the centre of each rear leg spacer. Do not glue the spacers, but let them move freely to help reduce friction.

4. The front axle needs two spacer blocks to prevent the inside pegs that cause the dog’s head to lift and fall, jamming against the edge of the head or body. Take a piece of 25mm diameter dowel and bore out the centre with a 10mm drill bit. Use a bandsaw to cut two 12mm lengths and slide them over the axle.

5. Cut two 9mm diameter dowels to a length of 20mm, and press them into the holes on the interior of the front wheels to form the pegs that will flip the dog’s head up and down.

6. The exterior of all wheels needs a 2.5mm pilot hole for the leg pivot points. Drill the 3mm pilot hole 12mm from the circumference of each wheel. Remember that each pair of axles needs a ‘one up, one down’ configuration to generate the walking action of the dog’s legs.

Step 13: Assembling and fitting the legs to the body and wheels

1. Assemble two pairs of front legs (parts F and G) using an M4 lock nut and 40mm pan-head screw with two M4 washers. The screw/bolt head faces inwards to avoid the screw jamming on the dog’s jaw.

2. Assemble two pairs of rear leg (parts H and I) rear wheels. Again, use an M4 lock nut and 40mm pan-head screw with two M4 washers. The screw/bolt head faces inwards to avoid the screw jamming on the dog’s body.

3. Both front wheel assemblies have an 18mm diameter × 15mm spacer between the upper rear leg and the dog’s body. The spacer causes the lower leg to line up parallel with the wheel exterior. Do not glue the spacers, let them move freely to help reduce friction.

4. Both rear wheels have an 18mm diameter × 5mm dowel spacer located between the upper leg and the dog’s body. Again, the spacer causes the lower leg to line up parallel with the wheel exterior. Don’t glue the spacers, let them move freely to help reduce friction.

5. A 10-gauge × 1¾in round-head screw passes through the rear of the front upper leg, through the spacer, and fastens into the dog’s body. Cut the spacer from 25mm diameter dowel and drill a 5.5mm hole through the centre to receive the woodscrew. Don’t glue the spacers, let them move freely to help reduce friction.

6. Use an 8-gauge × ¾in round-head, black Japanned screw with an M4 washer to fasten the lower leg to the exterior of the wheels. Line up the wheels to create the alternate lift and fall action of each pair of legs to create the walking action.

7. ‘Dry fit’ the whole dog toy assembly after fitting the head into place with two 8-gauge × ¾in round-head, black Japanned screws. Test the whole assembly for ease of movement, and adjust as necessary with files and glass paper. After testing, dismantle all the components and prepare for painting and final assembly.

Disassembled view of how the legs fit. Make sure the screw heads face inwards to avoid the nut and bolt striking the body. Finally, use a hacksaw to cut off the protruding bolt, and file the ends smooth.

Step 14: Finishing, decorating and assembly

1. As with previous projects, make sure to glass paper and prepare the components before assembly. Spray them with two coats of grey primer undercoat, and rub them down with 1,200 grit paper when dry.

2. Spray the underside of the body and head with two coats of a creamy, off-white enamel or cellulose paint.

3. Spray the top of the head and body with a dark brown colour. Aim to make a graduated change between the creamy underside colour and the upper brown colour. Spray the leg components, tail and wheels with the same brown colour.

4. Make a stencil/mask to spray a patchy pattern on the dog’s body with either a lighter or a darker colour. Apply two or three coats of paint spray, and rub down with 240-grit paper between coats. Use a 1,200-grit paper before applying the final coat of paint.

5. Spray the tail tip black, and also the wooden bead for the nose. Paint the eyes white, and add a larger pupil to stop the eye looking too reptilian.

6. When all the colour has dried thoroughly, add a coat of wax to surfaces in contact with each other to reduce surface friction. Polish the wax before assembly.

7. When all the components are complete, assemble them for the final time using PVA where appropriate. Glue both the 12mm-thick handle and the hand grip into place using PVA. Paint the eyes and nose, and glue them into place with a two-part epoxy adhesive.

8. Finally, use two pieces of leather or vinyl screwed to the top of the head for ears.

CHAPTER EIGHT

THE RETRO ROVING ROBOT TOY

The robot marches, rattles and clatters along, driven by an outside wheel pivot joined by a connecting rod between each wheel arm. As he strides mechanically along, his jaw opens and closes, driven by an eccentric cam and follower which is partially concealed between the axle and his body. He has a lovely big mechanical overbite, and a cheerful expression inspired by some of the mechanical toys and robot sciencefiction characters from the 1950s and 1960s. The plans for this character offer the opportunity of making a marching or a walking figure; they could also include a bent wire connecting rod between the arms and wheels, making him look less blocky and bulky.

To make the robot toy, prepare the following materials:

The completed robot toy.

CUTTING LIST FOR THE ROBOT TOY

Part | L × W × T | Quantity | Material
Body blank | 100 × 45 × 45mm | 1 | Redwood
Body blank sides | 100 × 45 × 10mm | 2 | Redwood
Head centre | 60 × 55 × 45mm | 1 | Redwood
Jaw sides | 70 × 40 × 6mm | 2 | Birch plywood
Jaw centre | 45 × 20 × 20mm | 1 | Redwood
Eccentric cam | 45 × 45 × 12mm | 1 | Birch plywood
Wheels | 70 × 70 × 18mm | 2 | Birch plywood
Cam follower | 85 × 9mm diameter dowel | 1 | Hardwood dowel
Axle | 65 × 9mm diameter dowel | 1 | Hardwood dowel
Cam follower guide block | 40 × 15 × 12mm | 1 | Birch plywood
Upper arm (walking action) | 70 × 20 × 10mm | 2 | Redwood
Lower arm (walking action) | 100 × 20 × 10mm | 2 | Redwood
Upper arm (marching action) | 140 × 20 × 10mm | 2 | Redwood
Lower arm (marching action) | 100 × 20 × 10mm(use a 2mm welding rod for the metal connecting rod) | 2 | 2mm brazing or welding rod
Antennae | 35 × 6mm diameter dowel | 2 | Hardwood dowel
Wooden beads | 10mm diameter approx. | 4 | Hardwood
Handle | 400 × 12mm diameter dowel | 1 | Hardwood dowel
Handle hand grip | 80 × 12mm diameter dowel | 1 | Hardwood dowel
Arm spacer | 10 × 18mm dowel | 2 | Hardwood dowel
Nose | 20 × 9mm dowel | 1 | Hardwood dowel

FIXINGS NEEDED TO PRODUCE THE ROBOT TOY

Part | Fastening | Quantity
Jaw pivot | 8-gauge × ¾in round-head, black Japanned screw with an M4 washer | 2
Shoulder pivot | 8-gauge × 1¾in round-head screw | 2
‘Elbow’ pivot | M4 lock nut and 25mm pan-head screw with two M4 washers. Screw/bolt head faces inwards to avoid jamming on the robot’s jaw | 2
Wheel pivot | 8-gauge × ¾in round-head, black Japanned screw with an M4 washer | 2
Screw for fastening eccentric cam wheel to the axle | 8-gauge × ¾in, countersunk-head woodscrew | 1

The templates for the retro roving robot need to be enlarged to fill an A3 page.

Templates for the Robot Toy

The templates for the robot toy need to be enlarged on to an A3 piece of paper in order to get the correct scale, proportion, and ratio of components. The best method is to enlarge the templates until the diameter of the wheel templates measure exactly 60mm.

Constructing the Robot Toy

Step 1: Shaping the body 1

1. Cut the centre piece for the robot body blank to measure 100 × 45 × 45mm.

2. Draw diagonals to locate the centre of the top and the underside.

3. Try-square a line around the blank 55mm from the bottom.

4. Mark out the housing for the cam to the dimensions shown using a marking gauge. The cam housing slot is 15mm in width, and is 55mm from the base.

5. Drill out the hole for the cam follower using a 9mm drill bit.

Cut out the cam housing in the centre piece that forms the robot body, using the dimensions shown.

6. Cut out the cam housing using a bandsaw or tenon saw.

7. Cut two pieces to form the back and front of the robot body (body blank sides). These act to partially conceal the cam follower and guide. Glue them over the front and back of the robot body blank to conceal the cam and follower housing.

8. Paste on the robot body template to the timber blank and drill the hole in the back for the handle. Set the robot toy body into the machine vice, and angle it to meet the 12mm drill bit at the correct angle shown on the paper template. Drill the hole to a depth of 20mm. Take great care not to penetrate the cam follower housing or the body shape will be useless.

9. Drill out the 10mm hole for the axle and the 3mm pivot point for the arms. Take care to pack the cavity for the cam housing as the drill bit is likely to split the timber as it passes through the cavity.

10. Centre punch and drill the locations for the axle hole, arm pivot clearance hole and the location for the hole for a handle.

The main body component for the robot body contains an eccentric cam and a follower that pushes the head up and down.

The two 10mm-thick front and back components act to partially conceal the cam and follower components. They also serve to give the figure extra width to hold the handle and allow for more interesting shaping.

Hold the robot body blank securely in the machine vice. Use a try-square to check for a true vertical. The hole must be drilled no further than 20mm, as space is very limited in the body blank. Eventually fit a 12mm dowel for a handle.

Step 2: Making the eccentric cam wheel

1. Use a compass to draw a 16mm radius circle on a piece of 12mm thick birch plywood.

2. Mark the location for the 9.5mm axle hole 13mm in from the circumference of the cam, and drill all the way through with a 9.5mm drill bit.

3. Sand the waste wood away to leave the circumference of the eccentric cam.

4. Drill a 3.5mm clearance hole on the circumference of the eccentric cam to meet the 9.5mm axle location.

5. Countersink the clearance hole to receive a 6-gauge × ¾in countersunk-head woodscrew.

Making the eccentric cam.

Step 3: Fitting the eccentric cam and axle to the body

1. Place the axle and eccentric cam externally over the axle area to work out how much of the back and front needs to be removed to llow the cam to rotate freely, while still concealing as much of the cam and follower guide block as possible. Plot the highest point of the eccentric cam’s rotation, and mark out how much of the body blank sides at the front and the back needs to be removed to allow the cam to rotate freely.

2.Use a tenon saw and file to carefully remove waste material.

The assembled robot body needs to allow the eccentric cam and guide block to rotate freely while still concealing as much of it as possible.

3. Fit the axle, eccentric cam and follower into place to test for ease of movement. Adjust as necessary with a file.

Step 4: Making the cam follower and guide block

The underside of the cam follower requires a guide block to prevent the head rotating and falling out. The cam-follower guide block also helps produce a smooth reciprocating head movement as the eccentric cam rotates beneath it.

1. To produce the cam-follower guide block, cut a piece of birch plywood 40 × 15 × 12mm from birch plywood.

2. Centre punch the location of the cam follower, and drill out the centre of the guide block using a 9mm drill bit. The hole needs to be centred extremely accurately.

3. Chamfer or slightly radius the top edges of the cam-follower guide block.

4. Glue the follower into the guide block and test it for ease of movement in the robot body. Carefully sand away any tight areas.

Shape and drill the guide block that attaches to the underside of the cam follower to prevent the head twisting and falling out. The follower and guide block assembly as shown.

The follower and guide block reciprocate as the eccentric cam rotates, causing the robot’s head to rise and fall.

Step 5: Assembling the robot body components

1. Glue the guide block to the underside of the cam follower. Place the follower and guide block assembly into place, and test for a smooth, accurate movement. Glass paper or file as necessary.

2. Place the wheel axle into place and screw the eccentric cam to it securely. Test for quality of fitting. If the cam sticks or jams, you may need to remove some material from the underside of the cam-follower guide block. The axle should project equidistantly from either side of the body to receive the wheels later.

Step 6: Making the head assembly 1

1. You can produce the head shape by pasting the template profiles on to card or thin ply and using them to trace on to a 60 × 45 × 55mm softwood blank. Each profile for the head has its own template.

2. Drill a 6mm diameter hole to a depth of 10mm for the robot’s head antennae. You can make these holes for the antennae by using a drilling jig made from a piece of timber with the appropriate angle cut into it. Place the head blank on to the angled timber jig and clamp both pieces into a machine vice.

3. Drill a 9mm diameter hole to a depth of 15mm on the underside of the head to receive the cam follower.

4. Drill a 3mm diameter pilot hole all the way through to receive the robot head jaw.

5. Drill a 9mm or 12mm diameter hole to a depth of 15mm for a nose.

6. Drill a 9mm diameter hole to a depth of 15mm for eyes.

7. After all holes are drilled, complete the basic head shape by cutting the side profile, then glass paper/sand.

8. Cut a 9mm or 12mm dowel to a length of 20mm to form the nose.

9. Cut two 9mm dowels to a length of 15mm to form the eyes, or use two 10mm wooden beads.

10. Cut two 6mm dowels to a length of 30mm to form the head antennae, and tap them into place.

Stages involved in making the robot’s head.

Step 7: Making the head assembly 2: making the robot’s jaw

1. Paste the jaw profile on to card or plywood to form a template.

2. Cut two jaw sides, and make a centre piece measuring 42 × 20 × 20mm.

3. Glue the jaw sides and centre piece to form the jaw shape, as shown. Line the edge of the jaw profile up to the furthest edge of the centre piece on both sides.

4. Leave the glue to set slightly, and then clamp the jaw assembly in a vice to dry. Make sure the parts don’t slide out of position.

5. Drill out the 4.5mm holes for the jaw pivot. Drill the assembly together to avoid holes not lining up. Use a scrap piece of 44 × 44mm to pack the cavity between the jaw so it doesn’t snap during drilling.

6. Sand and glass paper the centre piece to follow the contour of the jaw front edges. The curve is important as it allows the jaw to open and close easily as the head rises and falls.

7. Temporarily fit the jaw to the robot’s head and test for ease of movement. The head should rise and fall smoothly and easily as the axle is rotated, causing the eccentric cam to reciprocate.

8. Gravity causes the head to return to its original position. Glass paper the head and jaw to reduce surface friction and sticking.

9. Fit the 20 × 9mm dowel to form the nose. You could also use a piece of 12mm dowel.

10. Countersink the eye areas to receive the wooden beads for eyes, or use dowel.

11. Expand the holes in two 10mm wooden beads to be fixed to the ends of the head antennae.

Stages involved in making the robot’s jaw.

Temporarily fit the completed jaw to the head using two 8-gauge × ¾in round-head, black Japanned screws. Fit the completed head and jaw assembly to the robot body and test by rotating the axle to check the head rises and falls smoothly.

Fit the eyes, nose and antennae to the completed robot’s head.

Step 8: Making the wheels

1. Make two wheel blanks measuring 70 × 70 × 18mm.

2. Use a compass to draw a 30mm radius circle on both sides of each wheel blank.

Find the centres of each wheel blank by connecting the diagonals with a pencil. Use a compass to draw a 60mm diameter circle circumference.

3. Use a centre punch to mark the location for the axle holes and the pilot holes for connecting the arms to the wheels. The axle hole is 9mm, the pilot hole for the arm connection is 3mm.

4. Use a machine vice to hold each wheel blank securely. Drill the axle hole to a depth of 15mm using a 9mm drill bit.

Set the depth stop to drill an axle hole to a depth of 15mm.

5. To make the pivot point for the connecting rods attached between the wheel and the arms, mark a 2.5mm pilot hole 10mm from the edge of the circumference of each wheel, and drill to a depth of 10mm. Drill from the front of each wheel with the axle hole facing at the back or downwards.

The pilot holes for the arm connecting-rod pivots are drilled 10mm from the front of each wheel to a depth of 10mm.

6. Rough out the wheels using a tenon saw or the bandsaw. Don’t attempt to cut to the wheel circumference. Leave some waste.

Remove the corners from each wheel blank, but do not attempt to cut up to the circumference.

7. Complete the wheel’s circumference using the sander. Each wheel should have a 9mm axle-hole wheel on one side and a 3mm pilot hole for the arm connecting rod on the other. Radius the circumference of both wheels with glass paper.

8. Once all components are complete and ready to assemble, screw the eccentric cam to the axle using a 2.5mm pilot hole.

Use the sander to remove all the remaining waste material from the wheel’s circumference.

The cutting list and dimensions for the robot’s arms are shown. Note: if you want to make the marching action that uses a metal connecting rod, you will not need to make two of part B.

When finally assembling all components, fix the eccentric cam into place by holding the robot body shape upside down in a vice.

The assembled axle and wheels will look like this.

Step 9: Making the arm components

1. Choose which robot movement type you want to make: walking or marching?

Cut the arm sections to length, and centre the location of the pivot points by scribing with a marking gauge to find the centre. Radius the ends and all edges.

2. Use the cutting list illustration to prepare the arm sections you will need.

3. Cut the arm components to length, and mark out the location for the pivot points.

4. Centre punch the location for the holes and drill them to the required diameters.

5. Round over the ends of each arm section using a penny coin or similar to get the correct radius.

6. Glass paper and radius all edges and surfaces.

7. Prepare two spacer blocks of 25mm dowel cut to 12mm in length. These will be used to project the arms from the surface of the body to line up parallel with the fronts of the wheels.

Step 10: Making and fitting the arm components for a walking-action robot

1. Assemble two pairs of parts B and C to form the walking-action arms. Join the ‘elbow’ joints with two sets of M4 lock nuts and the 25mm pan-head screws with two M4 washers.

Assemble a pair of parts A and B to form the walking-action arms. Make the lock nuts face outwards to prevent catching against the robot body. Hacksaw and file the edge of the bolt smooth.

2. Place a spacer block between the shoulder join and the top of the arm.

The spacer block causes the arm to line up in parallel with the exterior of the wheel.

3. Screw the arm into place at the shoulder join using an 8-gauge × 1¾ inch round-head screw.

4. Repeat the process to locate the second arm.

5. When the wheels are finally glued into place, the pilot holes for fixing the lower arm to the wheel must be synchronized to cause an alternate rise and fall of each arm to create the walking illusion.

6. When all the parts are finished, decorated and sealed, join the lower leg to the wheel with an 8-gauge × ¾in round-head, black Japanned screw with an M4 washer.

Step 11A: Making and fitting the arm components for a marching-action robot

There are two ways to produce the marching action robot arms. The first uses a wooden connecting rod (part B), shown on the dimensioned arms cutting list that connects the arm to the wheel. The second method uses a metal connecting rod formed from a 2mm brazing rod (in place of part B). The metal connecting rod is more discrete and causes the robot toy to look less like a deckchair on wheels.

1. Assemble two pairs of parts A and B to form the walking-action arms. Then join the ‘elbow’ joints with two sets of M4 lock nuts and the 25mm pan-head screws with two M4 washers.

2. Place a spacer block between the shoulder join and the top of the arm.

3. Screw the arm into place at the shoulder join using an 8-gauge × 1¾in round-head screw.

4. Repeat the process to locate the second arm.

5. When the wheels are finally glued into place, the pilot holes for fixing the lower arm to the wheel must be synchronized to cause an alternate rise and fall of each arm to create the marching illusion.

The pilot holes on the exterior of the wheels must be synchronized to cause a rise and fall effect, or walking action as the individual arms rise and fall alternately.

Two methods or types of connecting rod for joining the arms to the wheels.

Step 11B: Making and fitting the marching arm using a metal connecting rod

1. The metal connecting rod is formed from a 2mm-diameter brazing rod with an 80mm space between the looped ends.

2. A simple bending jig could be formed from some 6mm diameter round steel and some 25mm flat bar. Alternatively you could use larger, long nose pliers to form the connecting rod.

3. Place the 2mm rod between the 6mm pegs of the bending jig, as shown. Bend the wire around the 6mm pegs individually to form the loops at each end. Make sure you bend the wire as close to the point where the wire meets the peg in order to avoid excessive curvature. Make a tight turn and twist.

4. Lift the wire shape off the bending jig and use a hacksaw to cut off the waste.

5. Crush out the excessive curvature in the rod by clamping it in the vice. Twist the ends of the loops to form a circle on the ends using long-nose pliers.

6. Use a hacksaw to cut through the end of each loop in the location and direction of the arrow. Cut through the wire where the long straight edge meets the loop.

7. Use long-nose pliers to adjust the angle of the loop on the end of the connecting rod. Close the ends of the loops by crushing them carefully in the jaws of the vice.

8. Use a ball-pein hammer to slightly flatten the ends of the connecting rod. This makes it fit better, and work hardens the ends to withstand bending.

9. Use emery cloth and files to prepare the surface of the connecting rod for painting. Fasten one end of the connecting rod to the ‘elbow’ of the robot arm using an M4 lock nut and a 25mm pan-head screw with two M4 washers. Fasten the lower end of the connecting rod to the wheel pivot point using an 8-gauge × ¾in round-head, black Japanned screw with an M4 washer. Make sure the wheels are synchronized to generate a lift and fall for each arm for every revolution of the axle.

Step 12: Making the handle

The handle for the robot toy is a 12mm dowel set to a depth of 20mm into the back of the robot toy. The angle for drilling the handle hole is drawn on to the template for the robot body. The method for drilling out the angled hole is described in step 1, stage 8. The handle should be cut from a 12 × 500mm length of dowel. A simple hand grip can be formed from a piece of 25mm dowel cut to a length of 90mm. Drill a 12mm hole to a depth of 15mm in the centre of the hand grip in order to fix at a right angle to the shaft of the handle. A Forstner drill bit would be ideal for this task.

Follow the location for the robot handle on the profile template for the body, and ‘dry fit’.

Step 13: Finishing, decorating and assembly

1. When all components are completed and rubbed down with 80-grit glass paper, followed by 120-grit, 240-grit and finally a 1,200-grit for a super smooth surface, stain them to the colours required using a spirit-based stain made from surgical alcohol and edible food dye. Leave the components for a day or two for the spirit to evaporate completely. Individual details can be painted in separate colours using enamel paint.

2. The example shown has decoupaged details printed and pasted on to it using PVA. To make the details, draw or collage a design on the computer, and print it in colour on to cartridge paper. Cut out the design and paste it on. Look for inspiration from the mechanical tin toy examples from the 1950s and 60s. Again, experimentation is the key to success.

3. Once dry, the components can be sealed with sanding sealer or cellulose lacquer for a more hard-wearing surface.

4. Glue the handle into place once the components are dry, and glue the handle hand grip to the top of the handle.

5. Assemble all the components for the final time using PVA where required.

6. Paint and glue in the beads or dowels for the eyes and nose with a two-part epoxy adhesive.

CHAPTER NINE

THE CRANKY CROCODILE

The Cranky Crocodile snaps and waddles along with enough character and menace not to be too twee. Children love him, and shriek with a mixture of fascination and fear as he ambles towards them.

The crocodile toy uses the same inside peg technique as the dog toy. A peg on the interior of the front wheels flips the head up and down to create the snapping action. With careful shaping the jaws will make a satisfying snapping sound as they close. The head is sculpted to give the reptilian texture and appearance of a crocodile, with the addition of teeth made from 4mm dowels set into drilled sockets in the toy’s mouth.

The legs use the outside wheel peg and pivot technique to create the impression of walking. The finishing touch is an articulated tail made from softwood strips bonded to a heavy canvas interface. The blocks are dried, shaped and sculpted to form a tail that flops from side to side as the crocodile is moved.

The completed crocodile toy uses the inside wheel peg technique to make the snapping action as he is pushed along. Gravity returns the jaw to the closed position, making two snapping actions for every rotation of the axle. The legs use the outside wheel pivot technique to make the walking action.

To make the crocodile toy, prepare the following materials:

CUTTING LIST FOR THE CROCODILE TOY

Part | Reference | L × W × T | Quantity | Material
Body blank | A | 300 × 90 × 20mm | 2 | Redwood
Head centre | C | 120 × 50 × 40mm | 1 | Birch plywood
Head/jaw sides | B | 150 × 100 × 9mm | 2 | Birch plywood
Wheel blanks |  | 60 × 60 × 20mm | 4 | Redwood
Front axle |  | 100 × 9mm diameter dowel | 1 | Ramin dowel
Rear axle |  | 75 × 9mm diameter dowel | 1 | Ramin dowel
Front axle spacers |  | 25mm diameter dowel × 15mm | 2 | Ramin dowel
Rear axle spacers |  | 25mm diameter dowel × 5mm | 2 | Ramin dowel
Upper front leg spacers |  | 18mm diameter dowel × 30mm | 2 | Ramin dowel
Upper back leg spacers |  | 18mm dowel × 20mm | 2 | Ramin dowel
Inside wheel pegs for front wheels only |  | 25 × 9mm diameter dowel | 2 | Ramin dowel
Head axle/pivot |  | 4mm diameter dowel × 80mm | 1 | Ramin dowel
Tail pieces |  | 100 × 20 × 20 | 24 |  | Redwood
Tail interface |  | 240 × 120mm | 1 | Heavy canvas
Eyes |  | 4mm hardwood beads | 2 |
Handle |  | 400 × 18mm diameter dowel | 1 | 18mm dowel
Handle hand grip |  | 95 × 25mm diameter dowel | 1 | 25mm dowel
Lower front legs | D | 100 × 50 × 9mm | 2 | Birch plywood
Upper front legs | E | 80 × 35 × 20mm | 2 | Redwood
Lower back legs | F | 90 × 65 × 9mm | 2 | Birch plywood
Upper back legs | G | 90 × 45 × 20mm | 2 | Redwood

FASTENINGS LIST FOR THE CROCODILE TOY

Part | Fastening | Qty
Shoulder Pivot | 8-gauge × 1¾in round-head screw | 2
‘Elbow’ Pivot | M4 locknut and 25mm pan-head screw with two M4 washers | 2
Wheel Pivot | 8-gauge × ¾in, round-head, black Japanned screw with an M4 washer | 2

Templates for the Crocodile Toy

The templates for the crocodile toy need to be enlarged on to an A3 piece of paper in order to get the correct scale, proportion and ratio of components. The best method is to enlarge the templates until the diameter of the wheel templates measures exactly 55mm.

The templates for the crocodile toy are labelled to correspond to the cutting list. The tail is shown separately for practical purposes.

Step 1: Making the body

1. Cut out two 20mm thick body profiles (A) and glue them together to form the thickness required. Use the first cut-out profile as a template to make a second.

2. Once the body shape has dried, drill out all the holes to the required diameters.

3. Expand the ‘shoulder’ holes to a depth of 15mm using an 18mm diameter Forstner bit. These holes will receive the 18mm spacer piece to project the upper legs away from rubbing against the body and to line up the front legs in parallel with the wheels.

4. Drill out a 12mm hole for the handle to a depth of 30mm. Place the crocodile body at an angle in the machine/hand vice for the pillar drill. Use the dashed line on the body template and a try-square to set up the body blank at a true vertical. Make sure to centre punch the location of the hole first.

The tail join is strengthened by pegging it using 6mm fluted dowels. Mark out and drill the holes 10mm in from the sides, and 15mm in from the top and bottom.

5. Mark out and drill four 6mm holes in the rear of the crocodile toy’s body to receive fluted dowel pegs for gluing the tail on to the body. It is important that the body is mounted vertically. Drill the holes to a depth of 10mm.

The location of the 2.5mm fixing points for the upper legs is expanded to 18mm to receive the spacers upon which the upper legs will pivot.

Step 2: Making the head

The head is a kind of bell crank operated by two internal wheel pegs placed within the front wheels. It works in exactly the same way as the head of the frog and dog toys.

1. Cut out the two head sides (B) from 150 × 100 × 9mm birch plywood.

2. Cut out the head centre (C) from a laminated block of birch plywood measuring 120 × 50 × 40mm. Five layers of 9mm-thick birch ply will suffice. A 5mm thickness will need to be removed later.

3. Glue the head assembly together, making sure the head centre measures slightly over 40mm in thickness before assembly. Allow the components to set slightly before clamping, and then check they do not slide out of position when clamped.

4. Once dry, drill out the completed head assembly to receive the head, the 4mm head pivot point, and the 4.5mm location for the eye sockets. Countersink the eye locations.

The completed head blank before shaping.

Rounding over and shaping the crocodile head and lower jaw.

Sculpting the details of the head, jaw and body. The image shows the crocodile’s head and body after shaping.

Step 3: Shaping the head and body

1. Peg the head assembly temporarily to the body with a 4mm dowel. Draw the basic tapered profile required for the final head form, then use a bandsaw and a 140mm drum sander with an 80-grit paper to remove the bulk of the waste. Round over the front end and the head contours. The finer detailing and shaping are done with rotary cutting tools. Refer to Chapter 6, which demonstrates the frog toy, for extra guidance.

2. Trace round the crocodile’s upper jaw where it makes contact with the lower jaw to guide the contours required for the front of the crocodile’s lower jaw. Remove the head and round over the contours of the crocodile’s head and body using the same process and technique as the frog and dog toy. Begin with an 80-grit paper fitted to a 140mm drum sander, and move to finer shaping with different diameter rotary cutting tools.

3. Use the 140mm drum sander with an 80-grit paper to sculpt the crocodile’s body. The process for shaping the crocodile’s head and body are the same as the process used to shape and form the frog and dog toy in the earlier chapters.

4. The finer details and shaping for the head are carried out using a range of rotary cutting tools. While you are not making a model for the natural history museum, it’s worth looking at a crocodile head to get the basic dimensions and features. Attempt to capture some of the subject’s basic characteristics and menace. Later you will add some teeth made from 4mm dowel to complete his ruthless reptilian grin.

5. Use rotary tools to carve some of the folds, creases and cracks in the crocodile’s head and body.

6. Mark out the location for about ten teeth made from 4mm diameter dowel. Locate them in such a way that some of them overhang to give the reptilian overbite. Drill the sockets for the teeth using a 4mm drill bit. Let some of the teeth hang over or outside the mouth area, just like its crocodilian cousins.

7. Use the rotary cutting tool to hollow out the interior of the crocodile’s upper and lower jaw to accommodate the teeth, taking care not to accidentally open the tooth sockets. Remove enough material to allow the teeth to close over each other.

Step 4: Shaping and fitting the tail

The flexible tail is made from angled timber strips glued adjacent to each other on both sides of a heavy canvas interface. Once dry, the strips will allow movement dictated by the angle cut on to the sides of the timber strips. A 5-degree angle is enough to allow for movement; any wider and the timber blocks tend to pinch the fingers.

1. Cut a 5-degree angle on both sides of a long length of softwood measuring 20 × 20mm in section. Eventually you need to have twenty-four 100mm lengths to form the tail.

Side profile of the template used for making the tail. Enlarge the template until it measures 220mm in length.

Carefully line up twelve timber strips either side of the canvas interface. Leave to dry for about six hours in a warm place.

2. Cut a piece of heavy canvas measuring 240 × 120mm.

3. Carefully glue a row of twelve strips of the 100 × 20 × 20mm timber strips on to one side of the canvas. Spread wood glue evenly and carefully, taking care not to allow gaps between the strips. Leave the assembly to dry off for an hour or so, and rotate it to repeat the process with another twelve timber strips on the other side of the canvas. Take care that all the strips line up on both sides. Leave the completed tail assembly to dry for several hours.

4. Place 6mm copper dowel pins into the holes previously drilled into the crocodile’s body, and press the tail assembly against the pins to locate the position for the second set of holes to receive the dowel pegs. The dowel pins will leave an indentation used to locate the position for the second set of holes to be drilled in the tail assembly. Mount the tail into a pillar drill and drill to a depth of 10mm. Insert the dowel pegs and ‘dry fit’ the tail and body together temporarily in order to locate the tail profile template accurately.

Use the copper dowel pins to locate the position for the second set of 10mm deep holes to complete the dowel join between the crocodile body and tail.

Place the tail template over the tail blank and trace its contours in the correct position. Cut the profile with a bandsaw.

After cutting the external profile, use the bandsaw to taper the tail profile from the front to the tip.

Use a 12mm rotary sander to cut the grooves, ridges and recesses to make a really reptilian tail.

5. Place the tail template over the front of the tail blank and trace round it. Cut out the tail profile.

6. Use a bandsaw to cut the tail so it tapers, or diminishes in width as it moves away from the point where it is joined to the body. Measure approximately 8mm each side of the tail tip, and connect with a straight-edge to the point where it connects to the crocodile’s body. Bandsaw the waste away.

7. With the tail pegged to the crocodile’s body, use a 140mm drum sander to sculpt the tail and blend the body and tail assembly together.

8. Glue the tail into place, and glass paper all the components, beginning with an 80-grit paper, progressing to a 240-grit, and completing with a 1,200-grit. The tail may need some manipulating to loosen it up.

Step 5: Making the wheels

The wheels are 55mm in diameter with a 2.5mm-diameter pilot hole drilled on the exterior of each wheel, located 15mm in from the circumference. The 2.5mm pilot hole is the fixing/pivot point for each leg assembly. In order to create the walking action, the holes need to be located one at the top and one at the bottom of each wheel in order to create the lift and fall action for each rotation of the axle.

Inside just the front wheels is a 9mm hole located 10mm from the circumference for a 9mm dowel peg: as the front wheels rotate, this will lift the jaw. Locate the 9mm hole for the interior wheel peg at the opposite end of the circumference to the 2.5mm exterior pilot hole for fixing the front leg assemblies. Use a centre punch to locate each hole accurately for the drill bit after marking out.

1. Begin making the wheels by locating the centre of each wheel blank. Use a ruler to connect the diagonals, and a compass to draw a 55mm-diameter circle. Repeat to locate the centre and circumference on the other side of the wheel blanks.

2. Select a pair to form the front wheels, and mark out the location for the interior pegs, 10mm from the circumference. Drill a 9mm hole to a depth of 10mm.

3. Drill the 9mm holes to receive the axles to a depth of 15mm on all four wheels. It is essential that the interior wheel pegs face inwards on the completed axle assembly.

The front and rear axles assembled. The front axle has two 9mm inside wheel pegs to flip the head up and down. All four wheels have spacers cut from 25mm dowel to stop the wheels jamming or rubbing against the body. The spacers also project the wheels to line up in parallel with the wheels.

4. Turn the front wheels over and mark out the location for the 2.5mm pilot holes, 15mm from the circumference for the leg pivot points. Drill to a depth of 15mm.

5. Repeat on the exterior of the rear wheels (these do not need the interior wheel pegs).

6. Remove the waste from the wheel blanks until they are completely circular.

7. Cut a front axle measuring 100 × 9mm diameter from dowel.

8. Cut a rear axle measuring 75 × 9mm diameter from dowel.

9. Bore a 10mm hole through a section of 25mm diameter dowel, and cut two 15mm lengths to form the spacers that will slide over the axles to prevent the internal wheel pegs jamming against the side of the crocodile’s body. Repeat to form two 5mm lengths to make the spacers needed for the rear wheels.

10. Cut two internal front-wheel pegs from 9mm dowel to a length of 25mm, and press into their locations on the inside of both front wheels. (It is better to sand and finish the wheels before gluing the inside wheel pegs into place.)

Step 6: Fitting the pivot points for the crocodile’s upper legs

1. Make two 30mm lengths of 18mm-diameter dowel, and tap them into the front upper leg location for the front legs to pivot from. You could think of them as the front shoulder location.

2. Make two 20mm lengths of 18mm-diameter dowel, and tap them into the rear upper leg location for the rear legs to pivot from. You could think of them as the hips, or rear leg location. After all glass papering is complete, glue in the leg spacer/pivot points.

Step 7: Assembling the legs

1. Assemble two pairs of front legs (parts D and E) using an M4 lock nut and 40mm pan-head screw with two M4 washers. Then screw/bolt head faces outwards. For the final assembly, use a hacksaw to cut away the protruding length of the bolt, and file smooth.

The legs are assembled and joined to the body as shown. The image also displays the upper leg pivot points projecting from the ‘shoulder’ joins.

2. Assemble two pairs of rear legs (parts G and F). Again, use an M4 lock nut and 40mm pan-head screw with two M4 washers. The screw/bolt head faces inwards to avoid the screw jamming on the crocodile’s body. For the final assembly, use a hacksaw to cut away the protruding length of the bolt, and file smooth.

3. Locate the centre of all four of the leg spacers on which the upper legs will pivot, and drill a 3mm pilot hole to receive a 10-gauge × 1¾in round-head screw.

4. Dry fit the whole crocodile assembly to test for accuracy and ease of movement. Remember the ‘one up, one down’ configuration for the pivot points on the exterior of the wheels.

Step 8: Finishing and painting the crocodile toy

1. As with previous projects, make sure to glass paper and prepare components before painting and decorating them. All parts should be sprayed with grey primer/ undercoat to seal the surface before spraying. Once dry, rub down the components with 240-grit glass paper to remove any raising of the grain, and to give a smooth surface before applying the colour.

2. Spray all components with a dark, chocolate-brown base colour.

3. This may seem weird, but wrap a pair of fishnet stockings over the crocodile body and components: when you spray the paint, the fishnet stockings will act as a mask and leave a fantastic reptilian, scaly skin effect. Check with the owner of the stockings before using them, although I am told that stockings with a suitable pattern are cheaply and easily available. When I bought mine explaining their intended purpose, I was greeted with a curious look by a rather matronly and less-than-convinced shop assistant. You could also use those net-like bags in which oranges and lemons are sold, to create a lovely mottled, textured effect.

4. First spray the model a dark green colour and leave to dry. Add a lighter green over convex areas and edges. The dark chocolate-brown first coat will give depth to the colour and appear as the cracks, creases and folds in the crocodile’s skin.

5. Finally, spray the underside with a creamy, ochre-like colour.

6. Paint the eyes with a yellow colour and add a diagonal pupil to get that cold, relentless, reptilian gaze.

7. When all components are stained and sprayed, seal them with clear cellulose or acrylic lacquer. When this has dried, give the components in contact with each other a coat of wax, and polish them later to reduce surface friction.

8. Make a set of teeth from 4mm dowel, and glue them into the sockets prepared earlier. Some can be longer than others to make the attractive overbite that crocodiles have. Obviously don’t sand and shape them into a point.

9. Glue the handle into place once the components are dry, and glue the handle hand grip to the top of the handle.

10. Assemble all components for the final time using PVA where required.

CHAPTER TEN

THE ROAMING RAPTOR

The raptor uses a linkage mechanism to cause the head to simultaneously lunge up and down as the jaws snap open and shut. A cavity inside the abdomen contains an eccentric cam to drive the head mechanism as the wheels rotate. Gravity keeps the head assembly in constant contact with the eccentric cam wheel. When you push or pull him, he charges along on legs connected to the wheels similar to those in the previous chapters, and makes a lovely snap sound as the jaws shut. The grasping forearms hang freely, waiting to grab his prey. The figure is completed with an articulated tail similar to the crocodile, which swings from side to side as the figure is pushed and pulled along. The addition of some 4mm dowel teeth complete his air of reptilian menace.

The completed roaming raptor toy.

To make the Raptor toy, prepare the following materials:

CUTTING LIST FOR THE ROAMING RAPTOR TOY

part
Reference
LxWxT
Qty
Material

Body blank
A
170 × 130 × 20mm
2
Redwood

Head sides
C
110 × 70 × 20mm
2
Redwood

Head centre
F
80 × 40 × 20mm
1
Redwood

Lower jaw sides
G
70 × 30 × 20mm
2
Redwood

Lower jaw and head lever
B
200 × 150 × 18mm
1
Birch plywood

Upper body spacer
D
140 × 80 × 20mm
2
Redwood

Lower body spacer
E
60 × 70 × 20mm
2
Redwood

Eccentric cam wheel
K
45 × 45 × 20mm
1
Birch plywood

Wheel blanks
L
80 × 80 × 20mm
2
Redwood

Lower leg
J
110 × 60 × 9mm
2
Birch plywood

Upper leg
I
90 × 50 × 20mm
2
Redwood

Head lever /linkage pin
 (through the body)

60mm diameter
dowel× 70mm

1

Birch plywood

Head linkage pin (through the top of the body and the connecting rod)

4mm dowel × 55mm
1
4mm dowel

Head linkage pin (joining the connecting rod to the top of the head)

4mm dowel × 55mm
1
4mm dowel

Jaw pivot connecting the lower jaw to the head

4mm dowel × 55mm

4mm dowel

Connecting rod between the head and body

55 × 20 × 12mm
1
Birch plywood

Tail pieces

100 × 20 × 20mm
24
Redwood

Canvas tail interface

240 × 100

Canvas

Rear leg spacer blocks

25 × 25mm diameter dowel
2
25mm dowel

Front leg spacer blocks

20 × 20mm diameter dowel
2
20mm dowel

Handle

400 × 18mm diameter dowel
1
18mm
diameter dowel

Handle hand grip

100 × 25mm diameter dowel
1
25mm
diameter dowel

FASTENINGS LIST FOR THE ROAMING RAPTOR TOY

Part
Fastening
Qty

Pelvis pivot
10-gauge × 1in round-head screw
2

‘Knee’ pivot
M4 lock nut and 40mm pan-head screw with two M4 washers.
Screw/bolt head faces inwards to avoid jamming on the dinosaur’s jaw
2

Wheel pivot
10-gauge × 1in round-head, black Japanned screw with an M4 washer
2

Shoulder pivot for
the front legs
10-gauge × 1¼in

Templates for the Roaming Raptor Toy

The templates for the raptor toy need to be enlarged on to an A3 piece of paper in order to get the correct scale, proportion and ratio of the components. The best method is to enlarge the templates until the diameter of the wheel measures exactly 70mm.

The templates for the roaming raptor toy are labelled to correspond to the cutting list.

Step 1: Shaping the body

1. Paste the components for making the body on to a 20mm-thick piece of redwood using a glue stick. You will need to make two of part A to form both sides of the raptor’s body; the centre is made by gluing parts D and E to form a cavity in which the head lever and the eccentric cam are located.

2. Take one part A (one side of the raptor’s body). Use a compass point or bradawl to make a series of pin pricks to locate the position of the internal spacer components (parts D and E).

Paste the body templates on to a 20mm-thick redwood board.

Use pin pricks made with a compass point or bradawl to locate the position of the internal spacer components.

3. Glass paper the template away and draw in the location for parts D and E: a good old-fashioned join-the-dots exercise. Refer to Chapter 4 ‘Tips and Techniques’ for additional help.

4. Cut out and glue Parts D and E into position and leave to dry. Remember to remove the paper templates before gluing.

Glue in the spacer blocks to form the cavity in which the eccentric cam and head lever are located. It is easier to cut out the head lever and cam wheel to test for ease of movement before the second half of the body is glued into place. The adjustments can be made using a bandsaw and sander.

The handle projects from the back at roughly 60 degrees, and the hole to receive the handle must be drilled before the body is shaped and sculpted.

5. Take the second part A with the paper template facing upwards. Use a centre punch to locate all the locations for the holes needed.

6. Glue the second body side (part A) into place and leave to dry.

7. Drill out the assembled body component to the required diameters shown on the paper template. Drill all the way through the body blank.

8. Remove the paper template with glass paper.

9. Mark out the location for the 12mm handle by mounting the body blank into a machine or hand vice using the dashed location line projecting upwards at a true vertical. Make sure the body is exactly parallel to the edge of the pillar drill bed to avoid accidentally drilling a compound angle. Use a try-square to align it correctly. Drill to a depth of 25mm.

10. Expand the location holes for the legs and arms using an 18mm Forstner bit to a depth of 15mm. These holes will receive the spacer blocks that keep the arms and legs off the surface sufficiently to sit square and parallel with the wheels, and not rub against the surface of the body.

The location for the pivot points for the arms and legs. Expand the holes already drilled to the required depth using an 18mm Forstner bit.

The tail pegs to the raptor toy’s body in exactly the same way as the crocodile toy’s tail. Use 6mm fluted dowels, and drill all holes to 10mm.

The sequence for sculpting and forming the raptor’s body. Use a 140mm drum sander and progress to a 25mm to form the ridges and smaller concave areas.

11. Drill four equidistant holes in the rear of the body assembly to a depth of 10mm to receive four 6mm fluted dowels to peg the tail to the body. Place the holes 15mm in from the outside edges of the body assembly, and 30mm apart. Use a marking gauge and try-square to help position the holes accurately.

12. Rough out the final form for the raptor using a 140mm drum sander fitted with an 80-grit abrasive paper. Begin by rounding over the edges and then forming a curve at the rear to receive the tail. Use a smaller drum sander to cut in the ridges across the back.

13. Take care not to radius the wheel location excessively as this might affect the toy’s stability. Radius just the immediate edges and the surfaces near the wheel locations.

Step 2: Making the tail

The tail is made in exactly the same way as the tail for the crocodile toy in the previous chapter. Softwood strips with a 5-degree angle cut along their adjacent edges are bonded on both sides to a heavy canvas interface. Once dry, the assembly can be cut and sculpted to form a flexible tail.

Label each strip with ‘T’ for top so you glue them facing upright correctly. When dry, use the template to cut the tail profile, and then cut a taper towards the end of the tail.

1. Cut a 5-degree angle on both sides of a long length of softwood measuring 20 × 20mm in section. Eventually you need to have twenty-four 100 × 20 × 20mm lengths to form the tail.

2. Cut a piece of heavy canvas measuring 240 × 100mm.

3. Carefully glue a row of twelve of the 100 × 20 × 20mm timber strips on to one side of the canvas. Spread the wood glue evenly and carefully, taking care not to allow gaps between the strips. Leave the assembly to dry off for an hour or so, then rotate it to repeat the process with another twelve timber strips on the other side of the canvas. Take care that all the strips line up on both sides. Leave the completed tail assembly to dry for several hours.

4. Place 6mm copper dowel pins into the holes drilled into the raptor’s body, and press the tail assembly against the pins: this will show you where to locate the holes for the dowel pegs. The copper dowel pins will leave an indentation, which will indicate where to drill the second set of holes in the tail assembly. Mount the tail into a pillar drill, and drill to a depth of 10mm. Insert the dowel pegs and ‘dry fit’ the tail and body together temporarily in order to locate the tail profile template accurately.

5. Place the tail template over the front of the tail blank and trace around it. Cut out the tail profile.

6. Use a bandsaw to cut the tail so it tapers, or diminishes in width as it moves away from the point where it is joined to the body. Measure approximately 8mm each side of the tail tip, and connect with a straight-edge to the point where it connects to the raptor’s body. Bandsaw the waste away.

7. With the tail pegged to the raptor’s body, use a 140mm drum sander to sculpt the tail, and blend the body and tail assembly together.

8. Glue the tail into place and glass paper all components, beginning with an 80-grit paper, progressing to a 240-grit and finishing with a 1,200-grit.

Step 3: Making the head

The head is a linkage mechanism connected to an eccentric cam located in the abdomen between the wheels. A connecting rod between the top of the body and the head allows the head to lunge forwards and back while simultaneously creating a snapping action of the jaws. Cut out part B from 18mm-thick birch plywood, or two layers of 9mm bonded together to make up the thickness.

1. Cut out two part G components to form the lower jaw. Glue them one on each side of the front of the lower jaw using the dashed line to align to the rear of their location.

2. Cut out part F (the head centre) from a 20mm-thick block made from birch plywood.

3. Glue the head sides (part C) one on each side of the head centre, and clamp until dry.

4. When the head components are dry, drill out all the holes to the required diameters. Pack the interior of the head/upper jaw to prevent the timber tearing.

5. Mark out the location for the eyes, and drill a 3mm hole to a depth of 10mm for each eye. The holes will then need to be expanded with a countersink bit to receive wooden beads for eyes.

6. Peg the head to the head lever with a 4mm dowel, and test for accuracy and ease of movement. Adjust as necessary with a file and glass paper.

7. Place the head assembly into the body cavity through the neck area and temporarily peg it into place with a 6mm dowel. Again, test for accuracy and ease of movement. It may be necessary to remove some of the width of the head lever to allow for maximum movement if it traps too easily against the interior spacer blocks (parts D and E). Dismantle the head and body assembly.

The sequence for shaping the head and lower jaw using drum sanders and rotary cutting tools.

Step 4: Shaping the head

1. Remove the upper head assembly and use a 140mm drum sander to reduce the width of the head, and cut a concave area into both sides of the lower jaw and lever component.

2. Place the upper head components over the jaw, and pencil in a rough profile to guide the orbital sander to complete roughing out the upper head. If not completed already, expand the eye locations using a countersink bit, and cut the remaining concave areas using a rotary cutting tool. Cut two nostrils using a rotary rasp fitted to the cutting tool.

3. Mark the location for about ten 4mm teeth made from dowel. Make an overbite by shaping the lower jaw to allow the teeth to overhang to a length of about 5mm. Drill the holes for the teeth to a depth of 5mm. Place the teeth into their sockets when all assembly and finishing is completed.

4. Hollow out the upper jaw with a rotary cutting tool to accommodate about six teeth in the lower jaw. Drill out the holes as near as possible to the edge of the lower jaw, whilst still allowing the jaws to close easily. Some extra sanding and shaping may be required to achieve this. They don’t have to be perfectly symmetrical dentures – just think of the T-Rex in the Jurassic Park films, where some teeth overhang and appear longer than others. Don’t sharpen them, but do make them menacing!

5. The head has a connecting rod fitted between the head and the top of the body, near the neck. Its job is to generate the head’s lift and fall action while simultaneously opening and closing the jaws. The connecting rod’s dimensions are 54 × 20 × 12mm. Drill a 5mm hole all the way through the connecting rod at both ends. Locate each hole through the centre, 6mm in from each end. Place a 4mm dowel through the top of the body and through one end of the connecting rod. The second peg passes through the top of the head and through the other end of the connecting rod. Press the lower end of the head lever in the underside and watch your beast lunge forwards and snap its jaws as the wheels rotate.

6. Disassemble all the components and glass paper them, beginning with an 80-grit glass paper followed by a 120-grit, then a 240-grit, and finally a 1,200-grit for a super smooth surface.

Step 5: Making the wheels

1. Refer to the wheel-making process in previous chapters to guide you. Begin making the wheels by locating the centres of both 80mm wheel blanks. Use a ruler to connect the diagonals on both sides of the wheel blank, then use a compass to draw a 70mm diameter circle. Repeat to locate the centre and circumference on the other side of the wheel blanks.

2. Drill the 9mm holes to receive the axles to a depth of 15mm on one side of both wheels.

3. Turn the wheels over and mark out the location for the 2.5mm pilot holes, 15mm from the circumference for the lower leg pivot points. Drill to a depth of 15mm.

4. Remove the waste from the wheel blanks until they are completely circular.

5. Cut an axle measuring 90mm in length from 9mm-diameter dowel.

6. Mark out and cut a 35mm-diameter eccentric cam wheel from 20mm-thick timber, and locate the 9mm axle hole using a centre punch. Drill all the way through with a 9mm drill bit. Shape the cam to a circle.

7. Assemble the raptor toy components, and test for ease of movement and accuracy. It may be necessary to remove some of the cam wheel on the circumference nearest the axle hole to allow the jaws to open fully. Be prepared for some trial and error. Despite drawing the components for this beast using CAD, I never quite get the same result twice – maybe something to do with the working properties of timber and slight human error?

Wheel and axle assembly seen from underneath. The eccentric cam will eventually be screwed to the axle.

Step 6: Making the legs and arms

1. Cut out and assemble a pair of legs (parts J and I). Glass paper and radius all edges prior to assembly using an M4 lock nut and 40mm pan-head screw with two M4 washers. The screw/bolt head faces inwards. For the final assembly, use a hacksaw to cut away the protruding length of the bolt, and file smooth.

2. Glue the spacer blocks into place for the arms and legs. Locate their centres and drill a 2.5mm pilot hole to a depth of 20mm into each spacer block.

3. Dry assemble the raptor toy and attach the legs. Screw them into place with a 10-gauge × 1¾in round-head screw at the hips, and an 8-gauge × ¾in round-head screw with an M4 washer where the lower leg pivots against the wheel. Test the whole assembly for smoothness and accuracy.

4. The arms can be built in two ways. One option is to make the articulated, puppetlike arm shown here with a pivot in the wrists and elbows. The arms are constructed from laminated, 6mm birch plywood pieces, and pegged with 4mm dowel. Once all the pieces for the arms have been glued, you can shape and sculpt them with a rotary cutting tool. This method allows the arms to wave around as the toy moves, and they look amazing if made correctly. The cutting list for making the jointed arms is shown below. In summary, it’s an excuse to elaborate and experiment with techniques and materials.

The diagram shows the suggested construction for a jointed arm prior to sculpting and shaping. The right-hand bottom image is a template for a simple, one-piece construction that can be left as a simple profile, or shaped and sculpted using a rotary shaping tool.

CUTTING LIST FOR THE JOINTED ARM

Part | Reference | Dimensions | Qty | Material
Outer upper arm | A | 60 × 30 × 6mm | 4 | Birch plywood
Inner upper arm | B | 80 × 20 × 6mm | 2 | Birch plywood
Inner forearm | C | 70 × 20 × 6mm | 2 | Birch plywood
Outer forearm | D | 60 × 20 × 6mm | 4 | Birch plywood
Hand/claws | E | 75 × 30 × 45mm | 2 | Birch plywood
Dowel pegs |  | 35 × 4mm dowel | 4 |

5. The second option is to make a much simpler plywood profile: this keeps all the reptilian menace, but is more robust and easier to make.

Test fitting the arms and legs for any adjustments. The screw heads face inwards, towards the body on the legs. They will also need to be countersunk or counter bored to a depth of 5mm to prevent rubbing against the body. The front-facing arms/claws can be allowed to hang and pivot freely so they wave around as your dinosaur clatters along.

The claws for the raptor toy are formed from a single piece of plywood that has been sculpted using a rotary cutting tool. You could produce a jointed/articulated claw/arm that could flail around as your beast is wheeled along. The claws screw into the ‘shoulder’ joints at the front of the toy. They can move freely or be fixed securely.

Step 7: Painting and assembling

1. As with all the previous projects, prepare the surfaces and paint them before assembly. The dinosaur has been sprayed with enamel paint in several stages. The reptilian skin effect has again been created by using fishnet stockings as a spraying mask.

2. Spray all components with two coats of grey primer/undercoat. Rub down the primer with 240-grit glass paper.

3. Spray all the components with a dark chocolate-brown colour as a base coat.

4. Roll on the fishnet tights and spray the upper body, upper head, wheels, arms and upper tail with a dark green hue. Spray the underside with a creamy yellow hue.

5. Spray the upper body and head areas with a lighter hue of green. Give the paint several hours to dry, and roll the tights away. You should be left with a reptilian skin pattern. Again, experiment on scrap material first.

6. Make a card stencil or mask to spray stripes across the upper body, the tail and the top of the head using a reddish-brown hue.

7. Use a brush to paint any smaller stripes, spots and details on the upper arms, legs and so on. Add any other decorative features of your own.

8. Leave the wheels the original green colour.

9. When all painting is complete, spray and seal in everything with a clear lacquer. When dry, add some wax to surfaces in contact with each other to act as a lubricant and reduce surface friction.

10. Glue in the handle and hand grip.

11. For the eyes, paint two 6mm wooden beads yellow, and add a black, reptilian vertical pupil.

12. Shape the teeth from 4mm dowel, and file a taper on the ends that point outwards. You can paint them a creamy colour. Tap them into place with a little wood glue.

13. Use a 1,200-grit paper to rub down any stubborn, raised wood grain, and assemble all the components for the final time.

CHAPTER ELEVEN

DEVELOPING YOUR OWN DESIGNS

Having completed the projects in this book, you are well on the way to being able to develop your own kinetic toys. The only constant to keep in mind is that it should be fun and rewarding. Try to keep your toy-making as a recreational activity, but set yourself challenges to solve, both technical and aesthetic. It can be immensely satisfying to step outside your comfort zone, even at the risk of ruining a component or project. New knowledge, discoveries and skills excite and invigorate the curious craftsperson. Experiment and try out ideas before launching into a project. Keep a journal, a scrapbook and a sketchbook to record your development of an idea or process. Some of the most satisfying moments are those where some large or small innovation is encountered and consolidated. Those little moments of cognition are priceless!

It can be all too easy to play it safe and settle into mind-numbing drudgery, especially if you are working on a commercial basis. Let the words of the Victorian poet Robert Browning guide you:

Ah, but a man’s reach should exceed his
grasp, or what’s a heaven for?

The Value of Drawing

Many people instinctively shudder at the thought of drawing. Graphic skills have been devalued and lost in many schools recently in the drive for greater literacy and numeracy. To explain and explore ideas in diagrams is perhaps the second most instinctive way we have for communicating ideas; it’s just that somewhere, we end up feeling a failure if we can’t draw like Raphael. Children are prolific and enthusiastic draftspeople, but as language develops, the instinctive need to explore ideas and feelings through drawing diminishes. Add to this the corrosive impact of instant gratification and information technology, and it’s clear to see why many children’s drawing skills are inhibited and stunted technically. Good drawing is a mind playing on a flat surface. Do you remember the joy of grabbing your pens, crayons or pencils and settling spread-eagled on the floor to while away the afternoon sketching and colouring furiously? You were never concerned about the work being any good, and neither were you precious about it. You were quite happy to work intuitively and freely.

The appeal of many folk toys lies in their immediacy and naïvety; the apparent lack of technical mastery does not detract from their charm or value. Don’t let your initial lack of confidence with drawing inhibit you. Drawing is subservient to the need to explain or explore an idea, and not a display of technical mastery. Don’t let the tail wag the dog!

Flat views are a perfect way of initially exploring ideas and developing your confidence. A contour or outline drawing can be a perfect way of exploring the external shape of an idea or component. Develop a daily sketching habit, and your technical prowess will grow. In time, you will find yourself thinking in three dimensions, and will be able to rotate an idea in your mind like a computer-generated model.

Study your subject matter to get greater insight and inspiration. The frog toy was designed and made after exploring frogs and toads through drawing.

There are lots of 3D drawing systems to explore to develop your drawing skills, such as perspective, isometric projection and oblique projection. Each has a useful quality, depending on what you are trying to communicate or explain/explore. Drawing is not an esoteric art! The basics can be easily acquired and developed.

Graphic materials have particular properties that make them useful for different applications. Traditional ink drawing pens are excellent for sketching ideas quickly, as they come with different diameter nibs and can be enhanced with colour and tone. Try lightly drawing detail with a HB pencil and then beefing up the detail you want to emphasize with pens.

Walt Disney insisted that his animators spent hundreds of hours drawing from real animals before distilling their essential characteristics into his anthropomorphic antics. It’s worth looking at and studying your subject matter to find inspiration and ideas.

Computer-aided design offers amazing opportunities to explore and communicate ideas. You can also generate formal drawings such as orthographic projection to generate production drawings to enable a third party to build your designs.

Use drawing to explore how existing kinetic toys work. Drawing is a fantastic way of analysing how something works, and happens in a mental timeframe that really helps you learn and remember a particular mechanism, process or technique. Some of the greatest innovators are prolific sketchers. Drawing is used to explore, explain and express. Most designing, including toy-making, is really a series of adaptations, refinements or improvements on products that already exist.

Developing Ideas through Modelling

Samuel Colt was said to be an extremely poor draughtsman and relied heavily on making wooden models to explain how, for example, the chambers for his repeating revolvers could be made to rotate. The models were then given to engineers, who planned their engineering and production – much to the chagrin of the unfortunate victims of his products.

Any number of materials can be used to explore ways of generating a mechanical action, though nothing compares to card and brass paper fasteners as a resource. Card modelling is an excellent way of developing the geometry and dimensions for mechanisms such as linkages, cranks and cams. The semi three-dimensional format offers an express route to working out the shape and location of components needed, and also helps in working out the scale and dimensions of a design. It can be a laborious process, with many pieces ending up in the bin until that elusive ‘eureka’ moment arrives. The card model can then be turned into templates to be traced on to the timber. But a note of caution: what works on a flat model does not always translate into three dimensions.

The raptor toy began as a series of card models, where a head attached to a class three lever is driven up and down by an eccentric cam wheel. The initial concept did not take into account how gravity would eventually cause the head to fail in making constant contact with the cam wheel. The mark two version placed the lever that controls the head motion in front of the cam wheel instead of behind. The revised card model uses the weight of the head and the kinetic toy designer’s best friend gravity to keep it in constant contact with the cam. The original version explored the addition of compression springs, but the favourite maxim by architect Ludwig Mies van der Rohe ‘less is more’ comes to mind. The mark one raptor head and body lies languishing in a bag and will be used as an experimental piece.

Finally, I hope you enjoy making these projects and feel enthused and inspired to be able to begin or develop your own kinetic toy-making. I hope you rediscover and refine your inner child, your innate playfulness and creativity, and find a desire to share the outcomes of your efforts with others.

Good luck.

The raptor toy was developed by making lots of card models and much experimenting with the dimensions and location of levers, linkages and cam wheels. The final design uses gravity to keep the head linkage mechanism in constant contact with the eccentric cam wheel.

INDEX

articulated tail 68, 78

axle assembly 75, 86

bandsaw 13, 36, 44, 45, 55, 73, 74, 84

beech 7, 9, 30

birch plywood 11, 41, 46, 54, 53, 56, 58, 68, 70, 78, 83, 84, 86, 88

brazing rod 63, 64

cam and follower housing 43, 56

cam and follower mechanism 22

cam follower and guide block 56

canvas interface 68, 72, 73, 82

card modelling 92

centre punch 13, 25, 33, 34, 35, 39, 43, 44, 49, 56, 58, 61, 62, 70, 74, 81, 86

chain and sprocket 18

colour 25, 29, 30, 32, 39, 51, 67, 76, 77, 89, 90, 92

Colt, Samuel 92

compound angle 33, 81

connecting rod 19, 53, 60, 61, 62, 63, 64, 65, 66, 78, 84, 86

conversion process 8

correct order 12

countersink 34, 37, 46, 56, 60, 71, 84

coping saw 36

cutting across the grain 9, 13

cutting list 32, 41, 53, 62, 63, 68, 69, 78, 79, 87, 88

datum point 12

decoupaged details 67

develop your own kinetic toys 90

dowel 27, 28, 32, 39, 41, 42, 43, 48, 50, 53, 54, 56, 59, 60, 63, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 82, 83, 84, 86, 87, 89

dowel pins 73, 74, 83, 84

drawing 86, 90, 92

drum sanders 12, 25, 26, 34, 35, 36, 47, 85, 72

dry assemble 36, 49, 87

dry fit 36, 39, 77, 84

dust extraction 12

eccentric cam 17, 49, 53, 54, 55, 56, 57, 58, 60, 62, 78, 79, 81, 84, 86, 92, 93

edible food dyes 31

enamel paint 29, 40, 67

epoxy adhesive 40, 52, 67

European white wood 89

experiment 31, 40, 67, 87, 89, 90, 93

Far Eastern plywood 11, 19

fishnet stockings 77, 89

fluted dowel pegs 70, 82, 83

folk toys 90

food colouring 40

Forstner bit 24, 28, 70, 81, 82

gears 17, 18

gluing 24, 25, 27, 44, 70, 76, 79

graphic materials 92

gravity 17, 21, 22, 92, 93

grey primer/undercoat 52, 77, 89, 52,

handle 19, 25, 26, 34, 39, 41, 44, 52, 55, 56, 67, 70, 77, 81, 89

inside wheel and peg mechanism 21

internal cavity 26

jig 28, 59, 65, 13

jointed arms 87

lever 15, 16,17, 26, 27, 32, 79, 81, 84, 86, 92, 93

lime wood 10

linkage mechanism 78, 84, 93, 16

lock nut 38, 42, 50, 63, 64, 66, 76, 77, 87

machine vice 13, 26, 34, 44, 55, 56, 59, 61

manufactured boards 11

MDF 32, 11

mechanism 6, 11, 15, 16, 17, 18, 19, 20, 21, 22, 23, 27, 28, 78, 84, 92, 93

mix and match different mechanisms 23

oak 7, 10

offset drive axle 20

offset wheel 19, 20

oil finishes 30

opposed offset wheel and axle 20

orbital sander 13, 85

outside wheel peg and pivot 68

pack the cavity 35, 46, 56, 59

paints 29, 30, 31, 40, 41, 52, 67, 77, 89

pan head screw 50, 63, 64, 66, 76, 77, 87

parallel 28, 34, 36, 50, 63, 70, 75, 81

pawl and ratchet 18

photocopier 33, 42, 43

pillar drill 13, 25, 26, 34, 45, 70, 74, 81, 84

pilot hole 28, 35, 36, 39, 49, 50, 59, 61, 63, 64, 75, 76, 77, 86, 87

pivot point 16, 17, 27, 35, 44, 46, 47, 48, 50, 56, 61, 63, 66, 71, 75, 76, 37, 82, 86

power tools 13, 25, 12

preferred sizes 8

pulley 17, 18

radius 25, 35, 36, 37, 45, 49, 56, 58, 61, 63, 83, 87

ratio 17, 18, 24, 33, 40, 55, 69, 79

recycling 9

ripping work 13

rotary cutting tools 12, 13, 25, 26, 37, 72, 73, 86

router 11, 12, 13, 35

sapele 7, 10, 11

Scotch yoke 18, 19, 20

scroll saw 13, 37

sculpt and shape 25, 44

shellac sealer 29

spacer block 27, 49, 50, 63, 64, 78, 81, 84, 87

spray paint 29, 41

sprockets 18

stencil 24, 32, 39, 40, 52, 88

synchronized offset wheel and axle 19

surface preparation 29

surgical spirit 30, 39

tenon saw 55, 57, 61

true vertical 43, 44, 56, 70, 81

types of motion 15

varnish 29, 30, 32, 39, 40

wax 7, 29, 30, 39, 40, 51, 77, 89

wheels in contact or engaged wheels 22

wood drill bit 24

wood dye 30

wood lathe 13

wooden bead 34, 46, 51, 59, 60, 84, 89

working properties of timber 86

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