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- Herausgeber: Fox Chapel Publishing
- Kategorie: Lebensstil
- Sprache: Englisch
- Veröffentlichungsjahr: 2021
The perfect resource for beginners, Metalwork and Machining Hints and Tipsfor Home Machinists is an informative anthology that combines useful advice and instruction with explanations of tools and techniques. With expert insight on a wide range of workshop practices and minor jobs that beginners may not be familiar with yet, this helpful guide will introduce readers to arbors and mandrels, belt jointing and splicing, shaft collars, finishing metal surfaces, G-clamps, cutting holes, hand turning tools, and so much more. Author Ian Bradley was an experienced engineer with a lifetime of experience in precision engineering and contributed to Model Engineer magazine for over 50 years.
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Metalwork and Machining Hints and Tips
Ian Bradley
Copyright © 2021 by Ian Bradley and Fox Chapel Publishing Company, Inc., Mount Joy, PA.
Copyright © Special Interest Model Books Ltd 2006
First published by Argus Books Ltd. 1988
Second edition published by Special Interest Model Books Ltd. 2006
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: 978-1-4971-0174-6eISBN: 978-1-63741-041-7
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
¼
20
28
0.250
5/16
18
24
0.313
⅜
16
24
0.375
7/16
14
20
0.438
½
13
20
0.500
⅝
11
18
0.625
¾
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 ½
M14
2.00
14.00
0.551
12 ½
M16
2.00
16.00
0.630
12 ½
M20
2.50
20.00
0.787
10
M24
3.00
24.00
0.945
8 ½
BRITISH INCH PRODUCTS
Size
T.P.I.
Major Dia.
BSW
BSF/BA
inch
8BA
59.1
0.087
6BA
47.9
0.110
⅛
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
¼
20
26.0
0.250
5/16
18
22.0
0.313
⅜
16
20.0
0.375
7/16
14
18.0
0.438
½
12
16.0
0.500
⅝
11
14.0
0.625
¾
10
12.0
0.750
7/8
9
11.0
0.875
1
8
10.0
1.000
CONTENTS
PREFACE
CHAPTER 1 Arbors and Mandrels
CHAPTER 2 Belt Jointing and Splicing
CHAPTER 3 Shaft Collars
CHAPTER 4 Finishing Metal Surfaces
CHAPTER 5 G-clamps
CHAPTER 6 Surface Gauges and Rule Holders
CHAPTER 7 Cutting Holes in Sheet Metal and Plate
CHAPTER 8 Making Special Nuts
CHAPTER 9 Hand Turning Tools
CHAPTER 10 The Wobbler
CHAPTER 11 Case-Hardening
CHAPTER 12 Machining Square Material
CHAPTER 13 Cross-drilling jig
CHAPTER 14 Fly cutting
CHAPTER 15 Screw jacks
PREFACE
Correspondents have suggested to the author that much of the information put out by him over many years should be collected, edited and published as additional volumes to ‘The Amateur’s Workshop’.
Accordingly, this material has been sifted and a choice made of subjects that should be of value both to the experienced amateur as well as to the novice himself.
Some of these subjects are basic to workshop practice, others are of a more advanced nature, but as none of them appear to be covered collectively in other publications, it is hoped that many workers will find this compilation useful.
Hungerford, 1988
Ian Bradley
CHAPTER 1
ARBORS AND MANDRELS
One of the minor problems of lathe work is to re-chuck partly machined components so that, for example, they again run truly with a bore previously formed. A typical example is a pair of ball-bearing housings situated at either end of a machined bore.
Here, the usual practice is to grip a length of mild steel or brass rod in the self-centering chuck and to turn it down to an interference fit in the bore of the workpiece.
Stub-mandrels made in this way are turned some ½ thou. oversize and the outer end is then eased with a fine Swiss file until, with the application of moderate wringing pressure, the component can engage for a sufficient distance to obtain a satisfactory hold. The projecting end of the mandrel should be center drilled, as for some operations the support of the tailstock may be required. After turning to size, and before the mandrel is removed from the chuck, it should be marked with a center-punch dot exactly opposite to the center of the face of the No. 1 jaw.
Fig. 1
Fig. 2
Where these mandrels have to be mounted in different chucks, it will be necessary to use the 4-jaw independent chuck rather than to rely on the self-centering pattern which usually exhibits some inaccuracy when measured over the full holding range.
The illustration Fig. 1 depicts six forms of mandrel that may be employed. The arbor (A) is the plain type we have been discussing, the work being held by friction only. At (B) one form of expanding arbor is depicted, the work being again frictionally held. (C) is a mandrel on which the work is positively secured by being screwed against a shoulder. At (D) the work is again held frictionally, a nut and washer being employed to force the work against the arbor shoulder. (E) represents an arrangement in which the work is restrained from rotation by means of a key, a nut and washer being used to secure the component endwise.
Fig. 3
Finally (F) demonstrates an arbor sometimes used, having a tapered seating upon which the work is mounted and secured by a nut and washer, friction only securing it against rotation.
EXPANDING ARBORS
There are many types of expanding arbors designed for machining work either in the chuck or between centers, so that true running is assured.
The arbor illustrated in Fig. 2 was made for machining a set of ⅝ in. bore cast-iron change wheels, and it was found that a secure grip of the work was obtained with the application of only moderate clamping pressure.
The details of the arbor are given in Fig. 3. The turning operations needed are all straightforward, but two points may well have some emphasis. In the first place the bore of the fitting should be turned to a push fit in the components it is desired to mount, and secondly when making the expander bolt its working should be checked before it is parted off from the parent material by screwing on the arbor with a component in place. If more than moderately light pressure is needed to lock the component to the arbor, it is advisable to ease off the apex of the screw’s coned surface as that is the base which first makes contact with the coned recess. In this way, the screw will act to better mechanical advantage in expanding the arbor, as the flexible portion of the latter is quite short.
MANDRELS
Mandrels are two types, plain and expanding. Both are used for mounting work so that it may be turned between centers. Probably the most accurate are the plain mandrels, a typical example being illustrated in Fig. 4. They comprise a hardened and ground shaft, accurately centered, having a slow taper formed upon it. In order to protect them, the centers are recessed, while the small end of the mandrel is marked with an incised ring as an aid to mounting the work. A flat is also machined on the unground portion at each end to serve as an abutment point for the set screw of the lathe carrier used to drive the mandrel.
As the accuracy of mandrels mounted between centers is wholly dependent on the correct alignment of these centers, it follows that they should be in good order and that the center set in the headstock is running true. A soft center is supplied for fitting in the headstock as it is quite a simple matter to set over the top-slide and turn the center true if need be.
Fig. 4
Fig. 5
In order to cover a wide range of work size, a great number of solid mandrels are needed. To reduce the amount of equipment needed various forms of expanding mandrel have been produced, and it is probable that the example illustrated in Fig. 5 may be one of the earliest. This is the Le Count expanding mandrel, made in Canada during the first World War. The writer has two of these devices in his workshop, the smaller having a holding range of from ½ in. to 1 in., the larger of from 1 in. to 1½ in. While not possessing the intrinsic accuracy of a plain mandrel, in view of their wide range, errors in true running have been reduced to an acceptable minimum.
The Le Count mandrels, which were bought many years ago at a trifling cost, have three undercut keyways machined in the body and these diverge radially from the axial line as they approach the base of the tool to form inclined planes. The three keys or jaws also have undercut faces so that they are retained in position as they slide in the corresponding numbered keyways.
Fig. 6
The work faces of the jaws are stepped to enable work of various sizes to be gripped and, at the large end, a projecting tongue is formed which is engaged by the large sliding sleeve. When this sleeve is pushed toward the base of the arbor, it draws with it the sliding jaws and these expand as they are forced along the inclined keyways.
Work is secured to the mandrel by slipping it over the appropriate jaws, and the large end of the body is then lightly struck with a copper hammer until a secure hold is obtained; the work is released by driving the sleeve carefully in the opposite direction. The mandrel illustrated part-sectioned in Fig. 6 is also of the expanding type, but its range of holding is necessarily restricted. The mandrel itself consists of a hardened cone ground to a slow taper on which is mounted a hollow, split sleeve, ground parallel on its outer surface and with an internal taper corresponding to that of the mandrel itself. A register peg is fitted to the mandrel to prevent rotation of the sleeve during adjustment.
The threaded end of the mandrel carries a ring nut that serves to move the sleeve along the mandrel. For this purpose the flange machined on the end of the sleeve lies in a recess machined in the nut, and a keep-plate maintains the parts in position.
SOME SPECIAL ARBORS
In addition to the arbors that have already been described, one has sometimes to make use of types that are somewhat specialized. Of these the two screwed arbors depicted in Fig. 7 are of the single variety and were made to hold some components in the vise of a shaping machine. For this reason the shank of the arbor has a pair of flats machined upon it to ensure that it can be gripped securely and accurately in the vise jaws.
Fig. 7
The purpose of the arbors illustrated in Fig. 8 and Fig. 9 will be clear to the reader from observing the large washers mounted on them. It will also be seen that the bodies of these arbors are slotted. This is to allow the bodies to be compressed, by lightly squeezing with the vise, to ensure that the threads formed in them grip the mounting screws firmly. All shake between the two parts is thus eliminated and the washers to be chamfered will run with acceptable accuracy.
Fig. 8
Fig. 9
The arbor illustrated in Fig. 10 was devised to enable punched steel washers obtainable commercially to be chamfered in order to improve their appearance. The arbor consists of two parts, a body (A) and a tapered member (B) upon which the washers are mounted. The end of the body is faced square with its axis, so that washers, when forced against it by the tapered member, will run true. Details of typical devices are given in Fig. 11.
Fig. 10
Fig. 11
