Making and Using Small Workshop Tools E-Book

Neil Wyatt

• Herausgeber: The Crowood Press
• Kategorie: Lebensstil
• Serie: Crowood Metalworking Guides
• Sprache: Englisch

Seitenzahl: 281

Veröffentlichungsjahr: 2023

Beschreibung

While pride of place usually goes to a lathe or milling machine, any workshop worthy of the name will have a host of hand tools and accessories to tackle a vast range of other tasks. Yet these are often supplied without detailed instructions, or even any guidance at all. Who has ever seen an instruction manual for a file? However, with the right advice, you can get better results, make your tools last much longer and work faster with less effort.

Leseprobe

First published in 2022 byThe Crowood Press LtdRamsbury, MarlboroughWiltshire SN8 2HR

[email protected]

www.crowood.com

This e-book first published in 2022

© Neil Wyatt 2022

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 this text 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 0 7198 4144 6

Cover design by Maggie Mellett

Contents

Introduction

A Word on Safety

1 Files and Filing

2 Measuring and Marking Out

3 Aids to Accurate Working

4 Heat-Treating Metals

5 Making Specialist Cutters

6 Workholding Aids

7 3D-Printed Tools

8 A Simple Milling Cutter Holder

9 An ER25 Collet Chuck

10 A Small Dividing Head

11 Making a Fly Cutter

12 Boring Tools

13 A Micrometer Boring Head

14 A Box Tool

15 A High-Torque Toolpost Spindle

16 Drilling and Reaming

17 Taps and Dies

18 Multi-Tools

19 Basic Gear-Cutting Tools

20 A Quick-Change Toolpost

21 Looking After Your Tools

Index

Introduction

I look back and realize that I have been participating in model engineering as a serious hobby for almost a quarter of a century, and enjoying being in and around workshops and tools for over twice as long. Yet, I recognize that I have more to learn than I will ever know about the subject. Even so, it is impossible to have hobby engineering as such a significant part of your life for so long without gathering a great deal of practical experience and useful knowledge. This book is intended to pass on some of the advice and ideas that I feel would have been useful when I first started out in this hobby. It is also a chance to bring together some of the small tools, jigs and accessories I have made in my own workshop.

In the past, books on smaller workshop tooling have focused solely on a series of shop-made gadgets and devices. Having been encouraged by the writings of Tubal Cain (Tom Walshaw), Stan Bray, Ivan Law, George H. Thomas and others, I have no doubt that such project-based ideas are really useful, not only as a practical guide to making useful devices but also for their insights and inspiration for designing and making my own workshop tooling. For that reason, this book includes many such project ideas at all levels, from the very simple to the fairly complex.

My aim has not been to provide every last detail on each example, as that could become very repetitive. Instead, most of the complex devices, such as the boring head and box tool, are fully described. Other ideas, such as the toolpost spindle based on a power drill gearbox and micrometer stand, are described in outline. They are intended to inspire you to go through your own ‘scrap box’ and work with what you have available.

What this approach misses, however, is the opportunity to pass on useful guidance on using and adapting commercial tooling. Usually, such advice appears incidentally in articles on some other subject, but in this book, I have tried to be more systematic. I have set out to pass on as much good, general advice of this kind as I can fit into one volume. It should help you make the most of your hand tools and small accessories, while equipping you with the ideas and knowledge to make many of your own.

It has been hard to decide what to cover and what to leave out because of it being too straightforward. I have decided to avoid items such as screwdrivers and I also abandoned a lengthy review of different types of hammer, but I have included many less intuitive tools. I have also gone into some detail on files, as I feel their potential and variety are poorly understood by many beginners.

I could have explored many useful workshop techniques, such as brazing and anodizing, but these would have strayed too far from the core subject. These pages do have a more detailed explanation of hardening and tempering carbon steels because these skills are essential for toolmaking, particularly when making specialist cutters of various kinds.

As a result of my approach, this book is a true miscellany, and no doubt every reader will find different parts more useful than others. Whatever you do in your workshop, and whatever your level of skill and knowledge, thank you for your interest in my thoughts and experiences. I hope that you find useful and interesting ideas in this book that will help you in your workshop journey.

Neil Wyatt

A Word on Safety

Some of the projects in this book involve the use of machine tools, which can of course present a safety risk. Even hand tools can be the cause of serious accidents if used unwisely. Below are some pointers towards the safe use of all workshop tools. Always remember that safety is your responsibility; if you are not sure about something, check with someone who is.

SAFETY CONSIDERATIONS

Electrics

As with any electrical equipment, care must be taken with leads and around the electrical parts of the machine, bearing in mind that tools move, and wires can be drawn into machinery. Ensure that plugs are wired correctly and that any fuses that blow are replaced with an item of the same type and value. If you have an electrical problem or you find your fuses blowing repeatedly, consult an electrician. Do not attempt to dismantle or repair any electrical elements of the machine unless you are competent to do so. If you use cutting fluid of any kind, take great care to make sure it goes nowhere near the motor, control box or wiring harness.

Emergency Stop

Make sure you are familiar with the emergency stop button on power tools. The more familiar you are with using one, the faster you will be able to hit it when you need to.

PPE

Most small tools do not demand much in the way of personal protective equipment, although the Health and Safety Executive (HSE) recommends that eye protection is worn when using a lathe or mill. When cutting something like brass, which can send a vertical shower of small chips into the air, full eye protection is essential. For most turning, many people find a pair of safety spectacles or goggles will be sufficient, but bear in mind that flying swarf is not the only risk. It is also possible for loose workpieces to fly out of the chuck at high speed. When using hand tools, use your judgement. For rotary tools, eye protection is essential, while hammers and chisels can cause chips to fly.

Fig. Safety.1 Safety googles are essential for eye protection.

Guards

While modern machines are generally fitted with good guards, older machines are often equipped with no guard at all, or with a tiny guard that serves little practical purpose. The worst examples offer no real protection in the actual working area and in some cases they even limit the usability of the lathe. If a guard interferes with the use of a machine, the user may be inclined to leave it open, which means that it is pointless.

Fig. Safety.2 A simple swarf guard from polycarbonate sheet mounted on a magnetic block.

I have found that a sheet of polycarbonate about 200–250mm (8–10in) square, mounted on an arm fixed to a weighted or magnetic base, can make a guard that is easy to use and effective. This can be easily cleaned and placed so that it protects the operator without interfering with the use of the machine.

Chemical Fluids

It may be a surprise to many, but the HSE has found that health issues such as dermatitis, asthma and lung damage from cutting fluid represent one of the biggest hazards associated with machining. Most people do not use floods of coolant – indeed, many do most of their work dry or just use small amounts of neat cutting oil applied with a brush or dribbled on to the work. This is less hazardous, but the fluid can still get thrown around or give off unpleasant fumes if the work gets hot. Take care to make sure you do not breathe in any fumes or overspray, and consider using barrier cream and/or a face mask.

Gloves and Other Clothing

Do not wear gloves when working with a machine like a lathe, mill or drill. If they are at all loose, they can be pulled into a moving machine, leading to terrible injuries.

It is unlikely that many people would consider wearing a tie in the workshop these days, but it is vital to be aware of any loose clothing. A more modern hazard are the drawstrings found on a hoodie, which can dangle right over the work as you lean forward for a closer look. The best workshop clothing is an overall with velcro or snap fasteners at the front. Be careful to keep long hair tied back, too.

Do not use cloth rags near moving work. Kitchen roll is much better as, if caught, it will simply rip and not snag.

Lighting

It’s always important to ensure the work area is well lit. Ideally, use low-voltage lighting and ensure that any luminaires are proofed against the entry of swarf or liquids. Avoid old-fashioned fluorescent lights, as these can give the impression that the lathe is not rotating if the machine speed synchronizes with the mains frequency.

Noise

Most machine tools are not excessively noisy. If yours seems to be louder than usual, it is probably trying to tell you things are not right; for example, a cut may be too heavy, causing shrieking chatter, or an interrupted cut may have been taken too quickly or aggressively. There may be times, however, when you cannot stop a loud or unpleasant sound from a particular tool due to some resonance or other. For these occasions, you can keep a pair of ear protectors handy, but a pack of cheap earplugs is cheaper and equally effective. Do take care, though, not to be caught unawares by someone entering the workshop when you are wearing them.

Fig. Safety.3 Ear plugs and ear protectors are both effective, so use what you find most comfortable.

Organization

In the real world, a workshop will not be as clean and tidy as an operating theatre, but that does not mean that you should work in the midst of chaos. Make sure there is plenty of space for you to move around and that there are no trip hazards waiting to catch you out when your attention is elsewhere. Keep wires and other tools out of the working area and try to avoid anything that might tempt you to lean over a moving machine.

Children

Responsible youngsters should not be discouraged from entering the workshop, but they must be properly supervised at all times. Make sure you take extra care for their safety and be mindful of the fact that any task you give them should be within their capabilities.

SOME DO’S AND DON’TS

◆Do give machining your full attention. Avoid distractions in the workshop. You will not do good work if you cannot focus on it and the majority of accidents are due to inattention.

◆Do remember that you are not the only person who may walk into your workshop and switch on the power, so make sure things are left in a safe state.

◆Do use eye protection and suitable guards.

◆Do take good care of your tools.

◆Don’t, ever, leave chuck keys in a chuck.

◆Don’t leave machines switched on when setting up work or changing tools.

◆Don’t try to remove swarf by hand. It is sharp and can easily cut or pull fingers into the work. Keep a bit of wire coathanger with an ‘L’ on the end handy, for use as a swarf ‘puller and poker’.

◆Don’t make electrical modifications or repairs unless you have the skills and experience required.

◆Don’t leave unattended machines switched on.

Safety is ultimately a matter of common sense and paying attention. Your eyes, ears and fingers are your most valuable assets, so take the same care of them as you would of any other irreplaceable tool.

1 Files and Filing

It seems appropriate to start by looking at files – some of the simplest and yet often most frequently misunderstood or abused of small tools. Files are hand tools with flat or curved surfaces bearing a series of fine teeth for the removal of metal. They usually have a pointed ‘tang’ at one end for fitting a handle. Ancient civilizations understood various ways of using abrasives, such as sand embedded in wood, and bronze rasps with many small teeth were known of in ancient Egypt and elsewhere. Metal files such as those that would be familiar today did not appear until the Middle Ages, when the means of making them was often a closely guarded secret.

Modern files typically are made of hardened steel and have regular teeth made by one or two sets of angle grooves. They come in various shapes, sizes and grades or ‘cuts’, from dead smooth through smooth to bastard cut, which is the coarsest. Files made by alternative methods of manufacture, such as the bonding of diamond or carbide particles to the surface, are increasingly commonly available.

Fig. 1.1 A selection of different file types.

FILING TECHNIQUE

The efficient and accurate removal of metal using a file is a technique that approaches an art. Good filing technique is an invaluable asset. In the past, it was a traditional first duty for any apprentice to take an irregular lump of metal and file it into some precise shape.

For large files, the best technique is to hold the workpiece in a vice, at elbow height. Traditionally, the file should be pushed gently forwards across the work, with one hand on the handle and the other steadying the far end. This is as much about accuracy and steady technique as applying extra force, and even small files can benefit from a steady finger pressure on their tip. Typical filing rates are around sixty to a hundred strokes per minute, and it is considered good practice to lift the file from the work, or at least remove all pressure, on the return stroke. Try to keep the file level, as otherwise the corners of the work will be rounded, or you may even end up with a convex surface.

Fig. 1.2 Shop-made C-spanner with draw-filed finish.

Fig. 1.3 Bar in vice for draw filing.

When aiming to size an object accurately it helps to have a scribed line or a witness mark – even a line drawn with a Sharpie – to work to. Strokes should be concentrated at the highest points but it is important to vary the position of the file to avoid making grooves in the work.

Draw filing is a useful technique for finishing flat surfaces, involving sideways strokes of a file held sideways with a hand at each end. It creates a similar texture to a surface finished by grinding, and is an excellent way to tidy up the sawn edges of steel plate. Draw filing is much less aggressive than ordinary filing and can be a useful technique when trying to achieve a close fit by hand.

Fig. 1.4 Slotted ‘top hat’ jig to guide filing of keyways.

Other uses for files include making keyways or notches. Fig. 1.4 shows a jig that can be inserted in a small gear or flywheel to guide the filing of a narrow keyway. It is just a simple top-hat shape that is a good fit in the bore with a filed or milled slot to guide the file. Opinions vary on whether it is better to harden such a jig or not, but if it is only for a single use, then it is probably best not to harden. It is always handy to have a file handy for tidying up the sharp corner or to ‘break the arris’ where two machined surfaces meet by creating a small chamfer. This is often done by draw filling along (not across) the edge as an alternative to a deburring tool drawn along the corner of the work. Such corners hold paint better as well as being more pleasant to handle. Care should be taken on scale models not to create an out-of-proportion effect by being too enthusiastic.

Files should have a well-fitting and comfortable handle fitted to their tang; not only is this essential to prevent injury on the tang, but it is also an essential aid to easy and accurate use. The smallest of files (those with round shanks) may be used without a handle, but these too will usually benefit from having one fitted.

Fig. 1.5 A quality handle for larger files.

A filing rest is a height-adjustable jig with two rollers used to support a file when it is being employed to put accurate flats on an object held in a stationary lathe. It usually has a raised ridge, to prevent the file making contact with and damaging the chuck.

Over time, files may clog up, especially when used on softer metals such as aluminium and its alloys. A brass wire brush or file card (a handle-less brush especially for this purpose) worked along the file’s grooves can bring back much of the file’s effectiveness. Another way to clean a file is to rub a hard brass rod across the grooves – it will rapidly adopt a shape that reaches into the grooves and clears the clogging.

Fig. 1.6 A stiff brass brush is an alternative to a file card.

FILE CUTS AND TYPES

Below is a broad overview of the commonest file cuts and their typical applications:

◆ Bastard-cut: the coarsest grade of metal file, used for rough shaping and the rapid removal of metal.

◆ Second-cut: with moderately coarse teeth, a good general-purpose file for metal removal and shaping. It is not suitable for fine finishing, although it can give a reasonable appearance when used for draw filing.

◆ Smooth: a cut with small teeth, giving a smooth surface finish.

◆ Dead smooth: a file with very small teeth, giving a fine surface finish. It is not suitable for the removal of large quantities of material.

◆ Single-cut: with a single series of teeth at an angle of about 25° to its length, this sort of file typically gives a smoother finish than a double-cut file of similar tooth size.

◆ Millennicut: a brand that supplies a single-cut file with very sharp, high-quality milled teeth that have ‘chip breaker’ grooves cut across them. Millennicut files are good for filing softer metals, such as pure aluminium, and even body filler, without clogging.

Fig. 1.7 Various file cuts (L to R): Millennicut with ‘chip breaker’ notches, curved, bastard, medium, fine and smooth.

Fig. 1.8 Examples of file shapes (L to R): round, crossing (bi-convex), half-round, flat, warding (flat and tapered), knife, three-square.

Files also come in a wide range of shapes, to suit various purposes, the commonest are:

◆ Flat: the basic rectangular cross-section shape of general-purpose file. It may be tapered at the end. Flat files often have a ‘safe edge’ – an edge with no teeth on it – allowing for working up to an internal corner without marking it. Before using a file in this way, it should be carefully inspected, as there may be burrs that will spoil the safe edge; if this is the case, they can be carefully ground or stoned off.

◆ Hand: very much like a flat file but tapered in thickness towards the tip.

◆ Square: a file with a square cross-section.

◆ Three-square: a file with an equilateral triangular cross-section.

◆ Half-round: a file with a cross-section convex on one side and flat on the other. The rounded side is used for filing concave shapes.

◆ Double convex: a file with an oval-shaped cross-section.

◆ Double-cut: a file with a second series of teeth cut across the first series.

◆ Round: a file with a circular cross-section.

◆ Rat tail: a round, tapered file with a circular cross-section, often rather coarse cut and used for opening out holes or filing notches.

◆ Knife: a file with a long, thin triangular cross-section.

◆ Taper: a file that reduces in width towards the tip, typically over around a third of its length.

As well as these more common types, there are also many options for specialist purposes. There are too many to list in full here, but they include rasps, which have individually cut teeth (normally coarse) and are typically used for softer materials such as wood or plastics. Also available are needle or Swiss files, which are small – typically 150–200mm (6–8in) long – and normally with a relatively fine cut. Such files are available individually and as sets in a wide range of different profiles. Quality is reflected in cost and the best single files will be more expensive than a whole set of cheap files. The name reflects the use of such files (and smaller) in Switzerland’s traditional clock- and watch-making industry. They are often supplied without handles. If the tang is rod-shaped rather than sharp, they could be used for light hand work without a handle but should never be used in this way near machinery. Push-fit handles are available to fit, some of which have a collet so they may be swapped between files.

Fig. 1.9 Small files (from top): round file in handle, two diamond-coated files with dipped handles, two Swiss files with miniature handles.

Fig. 1.10 Carbide-coated file.

Carbide files are suitable for use on tough materials. The cutting surfaces are covered with small pieces of tungsten carbide bonded to the surface, which function as teeth. These files are ideal for tidying up iron castings, which often have a tough ‘skin’. Diamond files similarly use tiny industrial gemstones bonded to a carrier and have much finer cuts. Diamond-encrusted ‘cards’ and ‘slips’ are particularly useful for tasks such as honing the edge on high-speed steel (HSS) or even carbide-tipped tooling.

Fig. 1.11 Diamond-coated files: note the flat file bent up, so it can function as a riffler for spot filing.

Fig. 1.12 Plastic-backed diamond slip for honing tools.

Fig. 1.13 Diamond-coated ‘card’.

Fig. 1.14 Carbide file in a hacksaw-like frame for tile cutting.

An abrafile is a long, thin file blade designed to be used under tension, so it is normally used fitted in a hacksaw, junior hacksaw or coping saw frame according to size (Fig. 1.14). For cutting rather than filing, it can cut in any direction and is ideal for cutting out complex shapes from sheet metal. Abrafiles are becoming hard to source; blades that are essentially rods coated in tungsten carbide chips are generally easier to find.

Riffler files are double-ended tools with a small, shaped file at each end. They may be dramatically curved or tapered and offer a multitude of solutions for filing delicate and unusual shapes. One very handy application is ‘spot filing’ a raised area on a flat surface using a convex riffler.

Fig. 1.15 Examples of riffler file shapes.

Fig. 1.16 These model locomotive coupling hooks were hand-filed from flat blanks.

FILE CARE

Files do not last for ever, but, if they are used with respect and stored so they cannot knock against each other, they will last longer than you might expect. A good tip is to keep new files for use on brass, where sharpness really affects how they work. As the files dull, move them on to steel and iron. If they clog up, particularly after filing aluminium, they can be cleaned with a ‘file card’, a board with stiff brass bristles, or a stiff brass or soft iron brush. Work these along the lines of teeth to remove the clog. Another way to clean a file is to take a length of brass bar and work the end of it across the file in the same way. It should rapidly adapt to the shape of the file and start clearing out embedded material.

FILE RACK

All conscientious workers realize the need to keep files so that they do not knock against each other and become blunt. Large files can be hung on hooks, stored in stacked tubing or kept in divided drawers. Small files such as Swiss or needle files usually come in plastic wallets, but these can become brittle with age and often fill with swarf. There is a need for something a bit more accessible that also makes it easy to choose between several files of the same pattern. Many people tend to keep some files for ‘best’ and others for regular use, meaning that they need quick access to those particular ones.

Fig. 1.17 3D-printed rack for small files.

One basic solution is to keep the files slotted into a rack made from a block of wood with holes in it, but this approach does not make it easy to see which file is which. Another solution is a 3D-printed file rack. The simple design illustrated here was created by ‘extruding’ the U-shaped cross-section, then subtracting a grid of rectangular blocks to create the spaces for the files. Initially, the rack was a bit crowded and the holes were a little too narrow for triangular and round files, but correcting this was easy, simply by stretching the whole design by a few per cent in its y-axis.

To minimize overhangs, print the rack on its front face. There should be no difficulty with bridging the relatively small holes for the files. Naturally, the as-printed plastic rack will be rather light, and it would be unstable when loaded with files. In this case, some nicely finished (but awful to machine) bright flats with rounded edges provided suitable material. This otherwise tends to get used for fabricating bearing pullers, brackets and the like rather than for permanent jobs. Two sections were cut to suit with the ends tidied on a finishing belt and superglued to the bottom of the rack. The result is as strong and stable a result as you might wish for!

FILING IN THE LATHE

The use of a file on rotating work in a lathe is usually to be avoided, as there is a high risk of injury if the file hits a rotating part or catches on the work. With due care, however, filing work in the lathe can be done safely – indeed, it is probably safer than using loose strips of emery cloth, a practice that results in many industrial injuries as fingers get pulled into moving machinery.

A clear view of the work and paying suitable attention are vital, and any file used with a lathe must have a secure and well-fitting handle. If a file is stuck by a moving jaw or otherwise pushed backwards, a bare tang can be driven through the palm of your hand or even into your wrist, with potentially awful consequences. A large, well-fitting handle is ideal. The very small handles that are sometimes provided with small files cannot always be trusted to give adequate protection or control of the file.

Observe obvious precautions: make sure the chuck guard is in place, and keep the file and items such as sleeves and fingers well away from the chuck. Always avoid using a file close to the chuck jaws, as contact can damage chuck, file and yourself. Eye protection is essential. When using the file, you can improve your control by gently holding the far end of the file with your left hand. Don’t leave the file still at any time as this may create a soft or blunt spot on the file. Gently apply forward strokes and don’t rush; let the machine do the work. For a straight chamfer, hold the file at a fixed angle; for a gentle curve, twist it sideways as you move it forwards.

Fig. 1.18 Specialist lathe file. It must be used with eye protection and with a handle fitted.

Although you can potentially use any file, a proper lathe file will give better results and will be easier to control. The Tome Feteira lathe file in Fig. 1.18 shows the single, rather steep cut of a lathe file. This pattern is chosen to be much less likely to grab. It also requires constant, gentle pressure away from the chuck to keep it in place. This means that if it loses contact with the work you have a natural tendency to push it away from the chuck. With its handle, the lathe file is about 400mm (16in) long, has two ‘safe’ edges, and feels a little heavier than most files. I find it much easier to control than an ordinary file for even relatively delicate work.

Fig. 1.19 Close-up of the single-cut surface of the lathe file.

Many people use emery tape to put a good finish on turned parts without realizing just how nasty the results of it catching on the work or chuck can be. The HSE offers some good practical advice, which in short is to use emery tape glued to a wooden backing. It can then either be used like a lathe file or levered against the work using a support. (Incidentally, the HSE’s guides to safe working practice are highly recommended. Far from being ‘nanny-ish’, they are full of practical advice and offer a sensible approach to safe working.)

Fig. 1.20 Emery tape.

HANDLES FOR SMALLER FILES

To reiterate, the use of file handles is not simply best practice; it is essential for safety and ease of use. Unfortunately, most handles for small files are too small and ordinary handles are too large. A better example is thing number 1866871, designed by Jangles1981 and downloaded from Thingiverse. It is one of three styles of file handle under this object (Fig. 1.21) and, like many objects on Thingiverse, it is shared under the Creative Commons–Attribution–Share Alike licence.

Fig. 1.21 File handle in Cura, a 3D print ‘slicing’ program.

These handles are well designed and printed, with adequate fill. Pushed on to 3mm file, they seem to hold them firmly. The Cura settings used are shown in Fig. 1.21. The flatter designs print more quickly but are perhaps not as comfortable to use. Perhaps the most important factor to watch for is that the handle should have a suitable socket to suit the file you want to use it with. Some designs benefit from heating the tang just enough to soften the print as it is inserted, to ensure a good grip, especially those for files with a taper tang. Be careful not to overheat and soften the file.

THINGIVERSE

Enter a term such as ‘file handle’ into the Thingiverse search box and you will be rewarded with many designs; handles large and tiny for files big and small. Be aware, though, that not all objects on Thingiverse are as well designed as the example of thing number 1866871. Some of them are virtually unprintable! The best approach is to search and find things that look like they will suit your purpose, then download them and try slicing them to see if there are any issues before committing to printing them. If the listing has an ‘I Made One’ section, you can see if other Thingiverse users have had success with the design, and the ‘Comments’ section may give useful tips on the best settings for a good print.

Another issue with Thingiverse is that most objects are available only as STL files. This is fine if you just want to print an object, and perhaps scale it or mirror it, but not as useful as having the original 3D model in a CAD format. One way this is addressed is that some objects on Thingiverse are ‘parametric’, which means they are written as computer programs. You enter dimensions or numbers for elements such as the number of teeth on a gear, and the program then generates an STL of the object to match your input.

Many of the objects on Thingiverse are covered by the Creative Commons–Attribution–Share Alike licence, which allows you to download and print an object, as well as modify it, ‘remix’ it, and share your own version, as long as the correct attribution is given.

Fig. 1.22 Two styles of 3D-printed handles for small files.

FILING BUTTONS

Filing buttons are a simple yet astoundingly useful aid to shaping components by hand. They are just round discs of metal fitted either side of a hole to guide hand filing and help with the production of a neat, round end. For a rough and ready result, just using a cap screw or cheese-head screw might be sufficient (Fig. 1.23), but with just a little more care you can achieve excellent results.

Fig. 1.23 Improvised filing button from a cap screw.

Obviously, in order to get a good result, the button should be exactly the same width as the bar, and the bolt that holds buttons and bar together must be a good fit in all three parts. This is not hard to achieve, even if you are using a plain screw to hold the parts, but do take time to measure the screw first. Many screws (especially metric ones) are significantly smaller than their nominal top diameter.

Filing buttons made from silver steel, hardened but not tempered, will be glass hard, the file will skid off them without damage, and they will not need to be left free to rotate. You can use softer materials, but if you do the buttons need to be able to rotate so that the file does not wear them away; this means a sloppy fit at the expense of a little accuracy. If you do not have material of the correct diameter, you can simply turn some down – the surface finish is not critical. Drill through a good snug fit for the securing screw, and part off two slices. These should not be too thin, like washers, instead aim for similar proportions to a full nut. Use the same drill on the component to be shaped – you can enlarge the hole to a larger size later if required.