Metalworking for Home Machinists E-Book

Tubal Cain

• Herausgeber: Fox Chapel Publishing
• Kategorie: Lebensstil
• Sprache: Englisch
• Veröffentlichungsjahr: 2021

Seitenzahl: 273

Beschreibung

No matter how well equipped your workshop may be, the need to make special tools, devices, and gadgets will always arise. That's where Metalworkingfor Home Machinists steps in to help! This highly-detailed guide shows you how to create 53 ancillary devices, including 5 clamps and vices, 10 jigs and fixtures, 25 lathe projects, and 13 miscellaneous projects. A must-have resource for every metalworking workshop, this manual will help save you time by devising the needed device for you so you can get right to work building what you need without delaying the completion of your final project any further! Written by an industry expert in designing and building engines and machines, author Tubal Cain had over 60 years of experience, and is a leading voice to guide you through the creation of essential workshop devices.

Leseprobe

Metalworking for Home Machinists

Tubal Cain

Copyright © 2021 by Tubal Cain and Fox Chapel Publishing Company, Inc., Mount Joy, PA.

Copyright © Special Interest Model Books Ltd 2005

First published by Argus Books Ltd. 1983

Second edition published by Nexus Special Interests Ltd. 1998

Third published by Special Interest Model Books Ltd. 2005 First published in North America in 2021 by Fox Chapel Publishing, 903 Square Street, Mount Joy, PA 17552.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior permission of the copyright holder.

Print ISBN: 978-1-4971-0172-2eISBN: 978-1-63741-043-1

To learn more about the other great books from Fox Chapel Publishing, or to find a retailer near you, call toll-free 800-457-9112 or visit us at www.FoxChapelPublishing.com.

We are always looking for talented authors. To submit an idea, please send a brief inquiry to [email protected].

AMERICAN INCH PRODUCTS

Size

T.P.I.

Major Dia.

UNC

UNF

inch

0

80

0.060

1

64

72

0.073

2

56

64

0.086

3

48

56

0.099

4

40

48

0.112

5

40

44

0.125

6

32

40

0.138

8

32

36

0.164

10

24

32

0.190

12

24

28

0.216

1/4

20

28

0.250

5/16

18

24

0.313

3/8

16

24

0.375

7/16

14

20

0.438

1/2

13

20

0.500

5/8

11

18

0.625

3/4

10

16

0.750

7/8

9

14

0.875

1

8

14/12

1.000

METRIC PRODUCTS

Size

Thread Pitch

Major Dia.

T.P.I.

mm

mm

inch

inch

M1.6

0.35

1.60

0.063

73

M2.0

0.40

2.00

0.079

64

M2.5

0.45

2.50

0.098

56

M3

0.50

3.00

0.118

51

M4

0.70

4.00

0.157

36

M5

0.80

5.00

0.197

32

M6

1.00

6.00

0.236

25

M8

1.25

8.00

0.315

20

M10

1.50

10.00

0.394

17

M12

1.75

12.00

0.472

14 1/2

M14

2.00

14.00

0.551

12 1/2

M16

2.00

16.00

0.630

12 1/2

M20

2.50

20.00

0.787

10

M24

3.00

24.00

0.945

8 1/2

BRITISH INCH PRODUCTS

Size

T.P.I.

Major Dia.

BSW

BSF/BA

inch

8BA

59.1

0.087

6BA

47.9

0.110

1/8

40

0.125

5BA

43.0

0.126

4BA

38.5

0.142

3BA

34.8

0.161

2BA

31.4

0.185

3/16

24

32.0

0.187

1BA

28.2

0.209

0BA

25.4

0.236

1/4

20

26.0

0.250

5/16

18

22.0

0.313

3/8

16

20.0

0.375

7/16

14

18.0

0.438

1/2

12

16.0

0.500

5/8

11

14.0

0.625

3/4

10

12.0

0.750

7/8

9

11.0

0.875

1

8

10.0

1.000

Contents

Introduction

SECTION 1

Getting Hold of the Job

The thinpiece vise

Circular work in the drilling vise

Thinning washers (Turner’s cement)

A soldering and brazing clamp

Packing for the machine vise

SECTION 2

Jigs and Fixtures

Why use jigs?

Co-ordinate setting out

Location jigs

Eccentric rod jig

A brazing jig

A cylinder boring fixture and alignment jig

A bearing boring fixture

Fixture for machining double eccentrics

A collet converting fixture

SECTION 3

Round and About the Lathe

The ball center

Setting over the tailstock

The spring center

Drilling an arbor for a draw bar

Turning fish-bellied rods

Crankshaft machining aids

A center-height gage and scriber

A micrometer screwcutting depth stop

Using 8mm watchmaker’s collets in a No. 2 Morse socket

A headstock length stop

A milling spindle drive or overhead

A truly mobile handrest

Rigidity of lathe tools

Tangential tooling

‘Gibraltar’ – a really rigid toolpost

Taking very fine cuts – ‘shaving’

Heavy drilling in the lathe

Cutting fluids and accessories

Splash guards

Extended chuck guard

Milling machine vise tray

Recovery

Leadscrew guard

My reminder

Protecting the taper sockets of the lathe

SECTION 4

Miscellaneous

Milling machine spindle speeds

Filing buttons

Making hollow mills or rosebits

A holder for throwaway endmills

A micrometer scribing block

Dividing from the chuck

Straightening copper tube

Cutting and threading copper tube

Awkward nuts

Catching rings and washers

Chatter on boring bars

My blackboard

Tailpiece

Introduction

Reprinting this title to bring it into the highly successful Workshop Practice Series has given me the opportunity both to introduce a number of new devices and to revise some of the original matter but one important change – metric equivalents to imperial dimensions – has not been made nor have Morse number drill sizes been corrected to millimeters. To have done this without cluttering up the drawings would have required that almost all of them be retraced. I have, therefore, assumed that readers are quite capable of making the conversions themselves where necessary.

I should, perhaps, explain the use of the word ‘simple’ in the title and the philosophy that lies behind it. I have the greatest respect for those who design and build sophisticated workshop equipment and do, in fact, take advantage of their work – it would be a poor workshop which had no tool-and-cutter grinder! But my interest lies in the designing and making of models of engines, real or imagined, or things for them to drive.

So, if any ‘manufacturing device’ is needed I always carry out a study of its cost effectiveness (cost in my case being mainly the time involved to make it) and unless any such device will either save a lot more time or will facilitate accurate working – preferably both – I will tend to disdain it. I try to look for solutions to problems which are both simple in conception and speedy in construction. Most of the ideas shown in this book can be made in a few hours (sometimes even minutes) and few require bought-in material.

In the introduction to the first edition I mentioned (at the suggestion of friends!) a sort of pecking order for the various devices, the implication being that these should be made first, but this does present many difficulties. My most used device – a little piece of wood or a length of string to hold bits together – is not shown! However, the following may help.

Over the years since the first edition was published, the center-height gage has been the most used by far, both for tool-setting and for marking out. As frequently mentioned in my other books, I now rough screwcut before using the tailstock die-holder whenever I can. The depth stop is invaluable and has also come in useful for milling flutes and cutting small gears. Toolposts – both the Gibraltar and that for hand turning – I would most certainly replace if I lost them. The overhead drive is not often used but how could I manage without it? I doubt if a week passes by without recourse either to a cross-drilling jig or the filing buttons. In short, the very fact that I have mentioned a device in this book implies that I have need of it!

Finally, to repeat myself, there is no single, unique solution to any engineering problem – that is what makes the profession so much fun. Do not be afraid to modify either design, dimensions, materials or construction methods to suit your own circumstances. Some of the devices described were made before I had even a vertical slide, let alone a milling machine!

Tubal Cain

Westmorland, 1998

The author at work!

The ‘heavy machining’ end of the workshop.

Workbench with storage under and the ‘light work’ area on the right.

The lathe – the ‘queen’ of machine tools.

The brazing bench, fitted with a turntable, which is sited outside the main workshop area (Photo Mike Chrisp).

SECTION 1

Getting Hold of the Job

A proper hold of the workpiece is fundamental to all manufacture, whether of models or in full-scale production. But we have a rather special problem as many components are either too small or too thin to grip firmly. We cannot afford either the time or the money to invest in the sophisticated workholding devices used in industry.

In this short section I have not covered the obvious accessories like chucks and bench vises, nor jigs and fixtures which come later. The former are normal workshop equipment and the latter are usually special for each job that crops up. However, I hope that the following pages may save a few workpieces, and perhaps also fingers, from damage. More important, they may suggest to you other ways of tackling those awkward jobs; if so, please don’t keep quiet about them – make sketches, take a photograph and send a note to the editor of Model Engineer (also published by Nexus Special Interests).

The thinpiece vise

The holding of thin material in the vise has always presented problems. The unit described here will overcome most of them for material down to about 32in. thick. It was originally devised as an apprentice training exercise by the supervisor of the training school of a large firm, and has given me excellent service for many years. The design has been simplified for the model engineer’s use, so that the drawings and the photographs do not quite correspond (e.g. items 4 and 5 are milled from a single piece of material in the original). See Fig 1.1.

Make the jaws, items 4 and 7 (Fig. 1.2) first, as these will be required as gages for the top plate and body. The ideal material is 1/2 in. square ground gage stock as this needs no preparation. Failing this, take an 8 1/2in. piece of 1/2 in. material and carefully file parallel and square. Keep the width to a uniform thickness – plus or minus 0.001 in. The depth is not so critical. File one end square, cut off a piece 4 1/16 in. long and repeat the process. (The squared ends will ultimately be the top of the jaws.) Coat with copper sulphate or marking blue and mark out all holes and the slots in the lower ends, taking all dimensions from the squared ends.

Tackle the slots before the rest, so that if this job goes awry as little work as possible is wasted. As an apprentice exercise these are made using hacksaw and file, which is probably quicker than attacking them with a 3/16 in. slot drill, but if a 2 1/2 in. x 3/16 in. slitting saw is available this will make short work of the cut. Run at about 60 rpm and feed the work in steadily, using plenty of cutting oil. Finish off with a 4in. warding file if need be, making the front jaw a tight fit on a 16in. thick gage (e.g. the material for part 5) and the rear jaw a sliding fit. Remove burrs.

Fig. 1.1 Thinpiece vise.

Drill and tap the holes in the front jaw, but leave the two No. 31 holes at the bottom for the present. The exact shape of the ‘oval’ hole in the rear jaw is unimportant, as part 8 can be made to fit. The quickest way is to drill two 3/16in. holes at a 5/6in. centers and file out the remainder, but professionals will doubtless use patience and a slot drill! Do not drill the a 5/32in. cross hole yet. Drill No. 37 as shown, open out one side to 1/8in. and tap the other side 5BA using the 1/8in. hole as a guide.

Now hold the jaws side by side in the vise – making sure they are the right way round – and file the previously squared ends to the 2 in. radius shown. The bottom end of the rear jaw may now be radiused, but leave the front jaw for the present.

The top plate, item 1, is best made from ground flat stock, but mild steel plate will serve if it is truly flat. File to shape and mark out the slot and the two rivet holes, taking care that the 5/32in. dimension is reasonably accurate. Drill a series of 3/16in. holes (1,000 rpm if ground stock, 2,000 rpm if BMS for HSS drills) well inside the lines of the slot and file until the jaws are a nice sliding fit. See that the ends of the slot are square. Start the rivet holes with a Slocombe drill, but do not drill through.

The body, item 2, calls for some energetic work with hacksaw and file to bring to the T shape. It is important that the top face be flat, and square to the front face with the 1/2in. groove in it. Mark out the front face for this groove, set up on the vertical slide with a piece of packing behind, so that the groove may be milled using the saddle cross slide, and make sure (a) that the 2 3/8in. wide top face is square to the lathe bed and (b) that the front face is square across the bed. Using a 3/8in. slot drill at about 650 rpm take a full depth cut across the center of the slot and then work carefully toward the two lines with light cuts until the front jaw is a nice sliding fit in the groove.

Now adjust the vertical slide until the center of the groove is at exact center height, and with a Slocombe drill in the chuck start a hole 9/16in. from the top face. Follow this with a 3/16in. drill to make a hole right through (hence the need for packing behind). Chuck a 3/16in. slot drill and cut the 3/16in. slot as shown, slightly deeper than the drawing requires. Remove the work, and transfer the center of the slot to the other side of the body. Set up on the vertical slide, squaring up as before; line up with the 3/16in. hole. Drill a 3/8in. hole on the center until it just breaks into the 3/16in. slot and follow with a 3/8 in. slot drill to machine the slotted counterbore (if your drills have a tendency to run oversize holes, use a No. 14 and letter U instead of 3/16in. and 3/8in.).

Fig. 1.2 Details of thinpiece vise.

Use plenty of cutting oil during the milling operations, and keep a steady feed allowing no rubbing without cutting.

The adjusting arm, part 5, is a simple filing and drilling job, best made of ground flat stock, but BMS flat will do. The row of holes can be drilled very accurately by mounting the arm (with packing behind) on the vertical slide. With a Slocombe drill in the chuck, deeply drill the first hole; advance the cross slide 156 thou, drill the next, and so on. The holes may then be finished to 1/8 in. in the drilling machine, but the pitch and alignment will be really true. Lightly countersink both sides. Do not drill the two No. 31 holes yet.

The two rivets, item 3, are turned from soft mild steel or from a longer 5/16in. iron rivet. The dowels, item 6, are parted off from ground BMS rod, not drill rod, and the pressure-pin, item 13, from drill rod. The locking plug, item 8, is made by chucking a piece of 3/16in. x 1/2in. steel in the 4-jaw, turning the screwed part 0.160/0.161 in. dia. and screwing 3 BA with the tailstock dieholder. The rectangular plug is then filed a nice fit into the hole in the rear jaw. Assemble into the jaw with the faces A’ flush, and drill in. right through. (Purists may prefer to drill No. 24 and ream, but this is not necessary.) Lightly countersink the entrances to the holes.

The nut and pin, items 9 and 10, are simple turning jobs, the exact shape of the heads being left to individual taste but knurl before parting off in both cases. The screw, No. 14, may be a standard Allen socket-head, if desired.

It should be possible to put the kink in the spring, item 11, without softening it, if held in the smooth jaws of the vise. If the holes are to be drilled, run no faster than 360 rpm, hone the drill point so that it is really sharp; rest the workpiece on a piece of steel packing and on no account hold the spring in the hand while drilling. It may be simpler to punch the holes with a sharp flat punch on a lead anvil.

Attach the front jaw 4 to the body 2 with a piece of paper (or .002 in. shim) in the bottom of the groove, using the screw 2. Clamp the top 1 to the body, ensuring that the jaw is hard up against the end of the slot. Drill and ream the two 3/16in. fixing holes. Dismantle and countersink the holes as shown and remove burrs. Insert the rivets 3, rivet up and carefully file flush. File the end of the slot in the top plate so that it is flush with the groove. It may be necessary to ease the slot a trifle to ensure that the jaw can slide up and down.

Insert the arm 5 into the slot in the jaw 4, first smearing some Easyflo paste flux on the mating parts. Check that it is square to the jaw. Drill and ream the upper hole; press in one of the dowels 6 and rivet lightly. Check for squareness, drill and ream the second hole and fit the pin as before. Heat to dull red, apply Easyflo silver solder, allow to cool to black, and quench in cold water.

File the lower end of the jaw to the profile of the arm, and smooth off the projecting pins. Polish off with fine emery. Attach the spring. Push the plug 8 into its place in the jaw 7, insert the pin 13 and lightly tighten the nut 9. Assemble the jaw to the arm 5 with the pin 10. The whole jaw assembly is attached to the body by the screws 14.

In service, the unit is held in the bench vise (with fiber grips in place) with the jaw 4 to the front, Fig 1.3. The projection of the jaws is adjusted by means of the screw 14 to suit the thickness of the job to be held. The rear jaw position is adjusted on the arm to suit the width of the workpiece, and the pressure pin positioned so that the spring opens the jaws to follow those of the bench vise.

My own vise has been in fairly constant use for 25 years. It would pay to harden the ends of the moving jaws. This can be done by casehardening; heat up to red and cover the top half-inch with Kasenit compound. Reheat to red again (see the instructions on the tin) and quench in water. There is no need to get the whole of the arm hot, of course. This operation should be done before uniting parts 4 and 5. After cleaning up and polishing this joining can be done but, while brazing, immerse the lower ends (that is, the hard tops) in a water bath. This will prevent drawing the hardness of the nose of the jaws.

Fig. 1.3 An underside view of the vise.

Although the top plate has got a little scarred with use I doubt if it is worth hardening this, although if gage plate is used it can be done by heating to about 800°C for say ten minutes (cherry red) and then quenching in oil, vertically. Temper to pale straw. The risk is that the plate may distort, and there is the added point that a hard plate will damage the files. My own is soft gage plate and the way things are going I may have to make a new top in ten or a dozen years’ time; cheaper than new files!

Fig. 1.4 In service – though the workpiece is rather thick!

Circular work in the drilling vise

All the books tell you that work should be clamped to the table or held in a vise while drilling, and this applies especially when working in brass or gunmetal. The material drags at the drill point and unless you have the old-fashioned straight flute drills (or the modern, and expensive, slow helix type) a ‘snatch’ when breaking through is inevitable. (You ought, of course, to take off the rake at the drill point when drilling brass and then resharpen for normal work, which means that after 12 months or so all your drills will be tiny stubs of HSS!.) So, drilling vise or clamp it must be. The snag comes when holding small round objects; stuffing box glands, for example. Even if your vise is furnished with vees on the jaw faces there is the risk of marking the carefully turned stem of the gland and if you don’t grip hard enough the drill will pull the job out of the vise and do more damage still; to you or to the job!

Fig. 1.5 shows how I got over this problem. The block is made from a piece of close-grained hardwood. Do not use oak – beech should do, and yew better still. But I use lignum vitae, which can be obtained from worn-out bowls woods or old foundry rammers. A good alternative is boxwood if you can get any. A series of holes, corresponding to the most common diameters you find in your work, are drilled through, the block having first been squared all over, of course. A small hole, I suggest 1/8in., is drilled as shown and the block then sawn through as far as this hole. It is held between the jaws of the vise and will grip the workpiece well if put in the right hole. There is, of course, no reason why it should not be cut into two separate pieces (it may break in two eventually) but I find it convenient to have it as shown in Fig. 1.5.

Fig. 1.6 shows a variation for holding such things as engine cylinder covers etc. I make mine to fit the OD of the flange as getting a better grip than on the spigot only. This one is bored in the lathe to suit the job in hand, and I make the block quite wide so that small cavities can be opened up if necessary. Naturally, either type gets riddled with and small objects can be used both sides of course, but even so will need replacing every few years. Why not make them of metal? No reason at all, holes after a while. That for the glands except that wood is cheaper and quicker to work. In passing, lignum is a real engineer’s wood. As you may know, it is used for stern-tube bearings on steamships and the old Alvis Firefly had lignum bearings in all the steering joints. So, you might care to consider using it as a chuck fixture when holding cylinder covers in the lathe, instead of making up a steel or brass split collet. I do and it is perfectly satisfactory.

Fig. 1.5 Holder for glands and similar small diameter work.

Fig. 1.5a Drilling a gland flange.

Fig. 1.6 Holder fordisks and similar work.

Thinning washers (Turner’s cement)

‘Making big ones into little ones’ was once the standard punishment for those sentenced to hard labor, and this work is still a penance to the model engineer, especially when it comes to washers or similar round objects which must be thinned. The problem is holding the things – or indeed any thin object of irregular shape. The thinpiece vise (here) doesn’t help and to alter it to hold washers still leaves the other awkward shapes which turn up every now and then. I suppose that everyone knows the dodge of pressing the article into a piece of softwood using the vise jaws, so that it makes itself a recess in which it can be held while filing. It is indeed very effective, and I have lots of bits of wood lying around (kept just in case another job of the same shape crops up) that testify to this! Opinions differ as to the best wood to use, but I find offcuts of yellow pine the best, with the work pressed into the side grain rather than the end grain as suggested in some books.

However, the method has its limitations, the chief being that it is difficult to get an even thickness and almost impossible to achieve any degree of precision. This is where the substance known as Turner’s cement comes in. There are many recipes ranging from neat shellac to a horrible mixture of resin and pumice powder. The easiest to make and use, and almost the strongest, is three parts of common resin mixed with one part beeswax. The wax is melted (with due precautions against it catching fire) and the resin, preferable in very small pieces, dropped in. The mixture is then heated a little longer and well stirred until it is seen that the two ingredients are both melted and well mixed. Cast it into sticks – I simply pour it into the vee of a piece of (clean) angle iron and then break up the length into convenient sizes.

It can be used in many ways. For woodwork the stick is held against the rotating faceplate until friction melts it on to the face. The workpiece is then similarly held against the cement coat until it again melts and then, when increasing resistance is felt, pressure is reduced until the work ‘catches’. Then let go, and you will find the work is securely held – it is as easy as that! For metal work this is rather hazardous, and I apply heat to the holding piece (faceplate or whatever) until the cement melts on to it in an even film. Then apply the warmed workpiece and heat again if necessary to get an even thickness. You must then let it cool, or hold it under the cold tap, until the stuff has set. I have a spare lathe backplate I use, but equally often I simply chuck a piece of scrap, face it true and use that. Fig. 1.7 shows half a dozen washers being so treated. These had to be thinned down to 0.020 in. thick, and cuts of about 5 thou were taken with no difficulty. All were equal in thickness within much less than half a thou. After machining they were removed simply by tapping them with a plastic mallet, although they could have been melted off if need be.

I have used this method in place of the ‘block of wood’, holding a flat chunk of cast iron in the vise, and on the lathe have faced down rings of up to 6 in. diameter. The grip is good (about 200 Ibf/sq.in. of contact area on test) but where there may be an interrupted cut care must be taken, as the cement won’t stand heavy shock loads. You will notice that in the photo the washers are all touching each other, in a ring, so that all help to take the shock as the tool passes over the holes. The method is, of course, a variant on the use of solder to hold things, but is less messy, doesn’t need so high a temperature, and is much easier to clean off afterward.

Fig. 1.7 Six washers attached to a carrier plate with Turner’s cement.

The cement can be used to hold pieces while milling, but both cut and feed rate must be small. I have used it on the drill, and no problems arose except that occasionally the work came adrift from the backing piece on breaking through. The one thing that must be watched – obvious if you weigh it up – is that you must not get the workpiece hot during machining! Coolant will have no effect on the cement.

A soldering and brazing clamp

Here is a little gadget you can make in an hour or so which will save you endless time and frustration for the next twenty years! The photograph on here shows the device in use, after brazing a butt joint between a 16 gage brass wire and a ring 1/8 in. wide x 28 thou thick – a job which normally means endless fiddling and even then often comes out all wrong.

I lay no claim to originality for the design. The incomplete ‘bits’ have been skulking around my workshop for many years and only a recent gap in the production program made me think of making up the missing parts ‘in case it came in useful’, which it did within a day or so, and I now regret that I didn’t put it in order years ago.

The drawing, Fig. 1.9, shows the details. The clamping arms are the most awkward part, as they must be springy. The one remaining original was of a very hard brass, and to get anywhere near the elasticity I had to work-harden a piece of half-hard brass strip by hammering it well. Possibly drawn brass might be hard enough as an alternative.

Cut out a strip about 9 in. long, say 16 gage, and planish it until you have reduced the thickness by at least three thou. If you haven’t a proper planishing hammer (which has a slightly convex face) you will have to use care and the flat of your light riveting hammer. Keep the work flat on a suitable anvil and ensure that the face of the hammer strikes flat as well. Use a multitude of medium-light blows – don’t give it a belting – and take care to get the impacts spread over the whole of the surface. Turn the job over periodically so that each face gets even treatment.

If the strip starts to bend sideways this means you are hitting one side of the strip more the other; give the next set of blows on the concave side to correct it.

Fig. 1.8 Brazing a butt joint between a wire and a narrow ring.

Cut off into 2 in. lengths (you need four) and mark out for the holes, noting that there are four holes in two arms and three in the other. Drill the 3/32 in. hole in the end, clamp all four arms together with a pin in this hole, and drill through 6 BA tapping size the holes common to all arms; then open out the clearing holes and the additional tapped holes in the ‘top’ arms, finally tapping as shown. The countersink on the end hole is to embrace the ball on the clamp head. I used a 5/16 in. drill point and this seems to work adequately.

For the thinned part in the middle, make a groove with a 3-cornered file on the center, 1 3/32in. from the end. Enlarge this with a rat-tail file, and then proceed with about a 10 in. half-round file, which will give about the right degree of curvature.

The inner face of the last 3/8 in. at the nose of the clamp is serrated – done either by making a pattern with your center punch, or by criss-crossing with a sharp chisel and light hammer blows.

Fig. 1.9 Arrangement and details of the clamp set.

Do this after forming the profile in plan, but before tapering the thickness. The ‘heel’ of the clamp (the other end, that is) must be rounded a bit to clear the ball head when at an angle. Finally, finish with fine emery and polish.

The ball head on the original (there was only one remaining) was turned from the solid, and you can do the same if you like. As a preliminary measure I cheated a bit, and used an old terminal from an ancient wireless set, but it didn’t fit the rod very well. So I made a new one and drilled a 1/4 in. bronze ball to about half diameter, finally brazing this to the complete body of the part. The only point about this component is that the cross-drilling must be accurate – use one of the many drilling jigs described later in the book – and the hole marked ‘to suit rod’ must be a good sliding fit.

The lockscrew is a fancy knurled knob, but it would work just as well with a plain cheese-head screw. Don’t omit the little pip on the end which prevents the thread from being burred over in use. I have specified phosphor bronze, as the thread will get a lot of use.