Building a Portable Steam Engine E-Book

Tony Webster

• Herausgeber: Crowood
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 203

Veröffentlichungsjahr: 2014

Beschreibung

This practical, instructional book describes the construction of a model of the Lampitt portable steam engine, which dates back to 1862, and which provided rotative power to drive threshing machines, circular saws, feed mills and other farm machinery. The construction of every component is described in precise detail and the text is supported by many helpful step-by-step photographs. In addition, useful advice is provided about obtaining materials and about the tools that are required to equip a model-engineering workshop. Accordingly, the information provided in this fascinating book will enable the reader to construct not only the Lampitt engine but also many other engineering models in the future. When the reader has finished building 'the Lampitt' he will, in effect, have completed an engineering apprenticeship, and will have a model engine of which he can be proud and which fully reveals the skills that he has learned. Fully illustrated with 142 step-by-step colour photographs.

Leseprobe

BUILDING A

PORTABLE STEAM ENGINE

A Guide for Model Engineers

TONY WEBSTER

THE CROWOOD PRESS

First published in 2014 by The Crowood Press Ltd Ramsbury, Marlborough Wiltshire SN8 2HR

www.crowood.com

This e-book first published in 2015

© Tony Webster 2014

All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publishers.

British Library Cataloguing-in-Publication DataA catalogue record for this book is available from the British Library.

ISBN 978 1 84797 866 0

DisclaimerThe author and the publisher do not accept any responsibility in any manner whatsoever for any error or omission, or any loss, damage, injury, adverse outcome, or liability of any kind incurred as a result of the use of any of the information contained in this book, or reliance upon it. If in doubt about any aspect of model engineering, readers are advised to seek professional advice.

Contents

Foreword

Introduction and Acknowledgements

1    The Background History and Development of Portable Engines

2    Workspace, Tools and Materials

3    Wheels

4    Axles and Perch Bracket

5    Boiler Construction

6    Boiler Fittings and Lubrication

7    Engine

8    Running a Steam Engine

Suppliers to Model Engineers

Index

Foreword

Tony Webster is well qualified to write this book on the Lampitt engine. Having known him for many years, I have always been impressed by his ability to root out the unusual prototypes and to adapt simple techniques and materials to do the job. His own collection of models is a testament to his ability and ingenuity. His workshop, housed in the garage of his house, is quite simple and does not contain elaborate machine tools; rather it displays the good solid evidence of hand work and simple fixtures.

If you are a beginner, expect to be instructed in the basic methods rather than sophisticated ones. Although a portable engine is not a complicated affair, there are some tricky techniques to be mastered, but Tony will guide you through them. There is also advice about materials and tools that you should not treat lightly. I have seen not only the model develop from its early stage on the drawing board, but also the original survivor at its home in the East Midlands, not many miles from where we both live. There is nothing ordinary about the prototype; it is a survivor, a representative of a bygone age in which traction engines and portables were built in small numbers by so many little businesses in the agricultural areas of the country. Each has its own unique features, but only the fittest of them survived well into the second quarter of the twentieth century.

I know that some modern techniques are included for the taking. I would urge you to take notice of them, as they will save time and effort and enable you to produce a good result. The boiler is something that must be taken seriously. Making even a simple example demands considerable patience and painstaking work. Above all do not hesitate to get help in this matter. Most experienced model engineers are only too pleased to help a beginner in the hobby.

Now start to enjoy this account of a journey that, I can promise you, will take much longer to complete than you would ever have thought.

D. A. G. Brown, C. Eng.

Introduction

This book details the construction of a portable steam engine and is written for the complete newcomer to model engineering. The making of each part will be described in detail, with hints on sourcing material and buying tools to establish your own workshop. When finished, you will have a complete steam engine that may be used to drive machinery. It will also be worthy of being shown at model-engineering exhibitions where you may receive recognition for the skills you have demonstrated. You will have gained many metalworking skills and completed an engineering apprenticeship of which you can be proud. Along the way you will have met many knowledgeable people and have perhaps joined a new group of like-minded friends.

Acknowledgements

I wish to thank my daughter, Susan, for her help with editing and the layout, and Derek Brown for help with the boiler and proof-reading.

This book is dedicated to my wife, Barbara.

1 The Background History and Development of Portable Engines

Portable engines, the forerunner of the traction engine, were made in large numbers in almost every county in the country from the 1830s right through to the 1930s, extending beyond the eclipse of traction engine manufacture. Most of the well-known manufacturers of traction engines produced examples, but many were made by blacksmiths and foundries that are now obscure and forgotten.

The early portables had horizontal or vertical boilers with a self-contained engine, often mounted on a frame or chassis, and the whole was supported by four wheels. By the 1850s they had developed into using a locomotive type boiler with the engine mounted on the top, indeed using the boiler as part of the structure of the engine. Two large wheels supported the heavy firebox end of the boiler and under the smokebox would be the turntable and two smaller wheels. These would be steered and hauled by a pair of horses in shafts, which would have been necessary to pull the 2 tons of engine over the rough roads of the time. Wrought iron wheels, mounted on a cast iron hub, would have been made in the foundry, or a local wheelwright would have supplied wooden wheels.

A locomotive boiler, as used on railway locomotives, has a large horizontal cylindrical part containing the fire-tubes, with the smokebox and chimney at the front, and a vertical square part containing the firebox at the rear. The steam cylinder was mounted machine, which would have needed another on top of the firebox and the crankshaft over two horses to pull it from farm to farm. Four the cylindrical part at the chimney end. horses might have been needed on wet and

The main use for such engines was to provide ‘rotative power’ for driving a thrashing machine, which would have needed another two horses to pull it from farm to farm. Four horses might have been needed on wet and muddy winter roads. An ‘outfit’ comprising a thrashing (or threshing) machine – known as a mill in Scotland – and an engine was often owned and run by thrashing contractors who travelled from farm to farm all winter, thrashing the farmers’ corn on the way.

Hornsby’s first prize engine of 1848.

A threshing machine, driven by a portable engine, in use in a Northamptonshire village in about 1900. BYFIELD PHOTOGRAPH MUSEUM; COURTESY OF POLLY HARRIS-WATSON

A portable engine driving a circular saw at the village sawmill. BYFIELD PHOTOGRAPH MUSEUM; COURTESY OF KEVIN PERRY

The combine harvester is a modern version of a threshing machine with a cutter-bar on the front and made to be self-moving.

Many sawmills were driven by portable engines that were given a permanent, static home in makeshift sheds made from surplus timber to protect the saw, engine and workers from inclement weather. Sawmill off-cuts provided a readily available supply of fuel for the fire.

By the 1860s some of these portables had been made or converted into self-moving engines by placing a chain around sprockets on the crankshaft and a rear wheel, but a horse was still needed in the shafts to steer the engine. In the 1870s the traction engine, as we now know it, developed from the portable engine by reversing the positions of the cylinder and crankshaft. This made the drive to the rear wheels within the reach of a train of gears. A cross-shaft and chain arrangement to steer the front axle brought the steersman and driver together on the man-stand at the rear. Traction engines changed little in the next fifty years or so. Portable engines, however, continued to be made throughout this period.

THE PROTOTYPE

The word ‘prototype’, in the context of model making, does not mean the first trial assembly of a new design, but the full-size example, which may or may not exist. In our case this is a portable engine, which we are going to replicate in model size.

The original full-size engine is a portable steam engine originally made by Lampitt & Co. of Banbury, Oxfordshire. An example from this period of engine construction has been deliberately chosen for its simplicity of construction, particularly the cylinder, which can be made from a piece of round gunmetal, or cast iron, bar. No castings will be used in its construction, except possibly for the flywheel, which could use an existing casting. However, a fabricated flywheel will also be detailed.

There seems to have been two Lampitts in Banbury: John Lampitt of the Vulcan Foundry, Neithrop (Banbury), millwright, iron founder and engineer; and Charles Lampitt of the Christ Church Works, Banbury, engineers, millwrights, brass founders and tower bell-hangers. It is unclear whether the company moved to larger premises, or whether John and Charles were of different generations.

C. Lampitt, Vulcan Foundry, Banbury, exhibited a horse-drawn seed dribbler at the Great Exhibition of 1851 at the Crystal Palace, London, but there is no mention of steam engines at that time.

John Lampitt made threshing machines in the 1860s (number 555 was made in 1861), but Lampitts built a combined total of only about twelve portable and traction engines.

SCALE

The question of scale needs to be discussed. The makers of model locomotives relate everything to the track width or gauge and the scale is determined by how much the prototype gauge of 4ft 8½ in has to be reduced to model engineering gauges of 3½ in, 5in or 7¼ in. Thus scales of ¾ in to the foot, just over 1in to the foot or 1½ in to the foot are used to scale the sizes down. Narrow gauge locomotives come out much bigger.

We are going to work to a scale of 2in to the foot, which will give us a model of about 18in in length; all dimensions will be in inches. The imperial system is the traditional measuring system for model engineers, mainly because the prototypes were made using this system. It may also be that, having bought our imperial drills and threading equipment, we are reluctant to change. Many school leavers have to learn the imperial system before they can start work in an established factory. However, there are many places where it may sometimes be an advantage to use metric-sized material where it is more readily available. These alternative sizes will be shown in parentheses after the imperial sizes, where appropriate.

Boiler

The usual starting point for the construction of a portable or traction engine is the boiler, which is there to make the steam and provide part of the structure of the whole engine. As you are just starting out in model engineering and do not yet have the tools and resources necessary to make anything in metal, the description of the boiler’s construction will be left until much later when you have gained some metalworking skills. However, the drawing for the boiler is included at an early stage to enable you to obtain a boiler from a professional boilermaker. There is no shame in buying your boiler: many experienced model engineers always obtain their boilers from a professional maker.

2 Workspace, Tools and Materials

The subjects listed in this chapter are in the same order in which they are introduced in the succeeding chapters.

SAFETY

Do not forget that most of the time you will be working alone. There will be no-one to help or switch off a machine if something goes wrong.

Always use a vice or clamp when drilling.

Only measure the workpiece when machinery is stationary.

Do not have any loose clothing, such as ties or cuffs, when using machinery.

Wear safety glasses.

TOOLS

The tools and materials that will be required to make this engine will be discussed below, together with their source of supply and their safe use. They should all appear in the order of their first mention in the text.

Before mounting your vice, check that a vertical bar is clear of the bench front.

WORKSPACE

The place where you carry out your model engineering activities needs careful thought. Will it be the garage, shed, kitchen or bedroom? A bedroom, although warm and dry, would be unsuitable for a machine shop or for hammering, especially if you live in a terrace or a semi-detached house, or anywhere with a hollow wooden floor. The use of the kitchen will have to come second to the needs of domestic life, especially when you are in the middle of something tricky. There is nothing better than a dedicated workspace, be it a garden shed or the end of the garage, where you can leave your tools on the bench and know that they will be there the next time you go in. It is most frustrating to have to set up your workspace every time you want to spend a few hours in the workshop, but many people work in these conditions and make wonderful models. In either case it is necessary to add some heat insulation in the form of fibreglass between the roof joists; a shed will need some more, or expanded polystyrene, in the walls. This will not only keep you warm in winter, but also cool in summer when the sun is beating down and you want to complete the present component.

For heating, use an electric convector or fan heater. Do not use a paraffin or gas-burning heater as the products of combustion include water vapour, which will make all your steel stock and your tools go rusty, and that is to be avoided at all cost. Also you will find that rock wool insulation falls apart when pushed up between the roof joists. Fibreglass holds together much better and stays put while you nail up some sheets of hardboard or even double-wall corrugated cardboard. White emulsion paint will help to brighten the interior and reflect the light from two or three five-foot fluorescent lights strategically placed over the bench and machine areas.

The bench is another area that needs some thought. A folding Workmate-style bench can be useful if you need the garage for the car as well, but some of the later models of bench lack diagonal bracing and therefore rigidity. A welded-angle steel bench, as big as you can accommodate, is ideal. The top should be 1¼in (40mm) thick and a lower shelf loaded with your metal and casting stock will help to keep it in place and aid rigidity. Screwing it to the wall also helps. The bench must stay in place when a file or hacksaw is used energetically.

A vice is essential to hold the workpiece and should be securely bolted to the bench top close to a leg – preferably the right leg if you are right-handed – not in the middle where the bench frame and top will flex and vibrate. An engineer’s vice of 3 or 4in width is ideal, but get one as big as funds will allow up to 4in wide. When installing a vice, ensure that a long straight bar can be held vertically between the vice jaws and clear (just) of the bench front edge. Don’t forget the bolt in the middle at the back.

THREE-JAW CHUCKS

These are supplied with two sets of jaws: one set for small diameters and one for large. The inside, or small, set is usually fitted and the large set supplied loose. Each jaw is stamped with numbers (1, 2, 3) and the slots in the front face of the chuck body are similarly stamped. It is important that the jaws are only ever fitted to their own slot. Start by removing the unwanted jaws by turning the chuck key anticlockwise in one of the keyholes. Keep going until the jaws stop moving and they can be removed by hand. All three will move out simultaneously, hence the term ‘self centring’.

Looking into the slots you will notice a disc with a spiral groove that appears to move inwards or outwards when the chuck key is turned. Now examine the jaws. Keep the two sets separate and observe the curved grooves that engage with the grooves on the disc or scroll. Keeping all the groove curves the same way round, you should find that the steps on the other set are opposite.

You will need the set with the largest step at the top. Identify the number of each jaw and place them ready, in order, with no. 1 at the top. Find the slot marked ‘1’ and turn the chuck key clockwise, turning the scroll anticlockwise, until the outer end of the scroll groove is just about to emerge in slot no. 1. If it emerges you will have to back it off. Slide the no. 1 jaw into the no. 1 slot until it engages with the scroll. Turn the chuck key clockwise and the jaw should be drawn inwards. Do not let the groove pass the no. 2 slot. Back off, if necessary, and slide jaw no. 2 into slot 2 and so on with no. 3. You will find it easier to turn the chuck around a bit between fitting jaws. Wind the jaws into the middle of the chuck where they should all arrive together. If they do not, you will have to repeat the whole process.

Three-jaw chuck with inside jaws fitted. The outside jaws are supplied loose.

DRAW FILING

Using the soft jaws, grip the workpiece in the vice, near to the end, with half the width above the jaws. Using a 6in or 8in smooth file, grip the handle with the right hand. With the left hand holding the end of the file (like when holding straight cycle handlebars), and with your left hip against the bench, push the exposed part of the file along the edge of the workpiece, keeping the file horizontal side to side. The file is travelling and cutting sideways for a distance of 5 or 6in. Repeat until the edge of the workpiece is smooth. The workpiece is then moved along in the vice and the next part cleaned up, blending the end of the stroke in with the last position. This is a very useful technique for smoothing the edge of a piece of metal. Deburr the edges of the workpiece.

Second tap, split button die and die nut for final sizing.

TAPS AND DIES

Model engineers usually use BA (British Association) threaded nuts and bolts. The which range of taps and dies required to this standard will include 2, 4 and 6BA. If starting from scratch, which is what this book is all about, you may prefer to start by establishing a set of metric taps and dies, perhaps from M3 to M5.

Taps and dies

Straight and chuck-type tap wrench.

The tools used to make an internal thread are known as taps. All sizes of taps come in three types: taper, second and plug (or bottoming). The last of these, as its name indicates, will cut the thread to the bottom of a blind hole. There is no real need for a taper tap in our work, so second and plug taps will make an adequate set. (Taper taps are more necessary when making course threads.)

A tap wrench, preferably of the chuck type, will be needed to turn the tap. The chuck type of tap wrench effectively lengthens the tap to make it easier to position and make sure that the tap is square to the face of the workpiece. It is important to make sure that the tap is square, meaning at 90 degrees to the surface of the job, assuming that the tapping size hole has previously been drilled square to the work face.

A die, for threading a rod or bolt, is tapered on the side where the size and manufacturer’s name are stamped; and that side is used to cut the thread first. If it is necessary to make a thread right up to a shoulder or step in the diameter, the die is turned over and run down again.

A die is held in a stock, which may be obtained in several standard sizes (13⁄16 in and 1in will cover our needs) and has screws to adjust the die to cut the thread to fit the tapped hole. Always tap the hole (female) first and adjust the male thread to fit.

To adjust the die, the central screw fits in the split in the die and forces it open, making the thread larger. A second pass will be needed to bring it to a size to fit the tapped hole. The side screws help to drive the die round and keep a blunt die from opening up when threading some materials. Slacken the outer screws before tightening the centre screw.

The size of a tap and die are based on the diameter of the male part (the rod or bolt from which metal is cut to form the thread). The female part is drilled to a smaller size, known as the tapping size, and metal is cut from inside the hole, by the tap, to make the internal thread. The tap is nominally the same diameter as the rod or bolt.

Die stocks of 13/16 in and 1in.

Tapping Drills

It can be helpful to establish a set of tapping size drills, which are most usefully stored in a block of wood set with a row of holes for the tapping drills and two rows for the second and plug taps. A fourth row of holes could be for clearance size drills, but it is all too easy to make a mistake and pull out a clearance drill instead of a tapping drill. The fifth row is for small nails or panel pins over which the dies are placed. Of course, the tapping drill, second tap, plug tap, clearance drill and nail will be in a line in the other direction. It is a bit tedious to make one of these blocks, which uses a different size of drill for almost every hole, but it will be very handy in the long run and useful practice. Do not drill right through or your drills and taps will fall through. However, if your block is little more than ½in thick, drill all the holes right through and glue a piece of plywood or hardboard onto the underside. While marking it out include all sizes from, say, 0 to 10BA or, in another block, M2 to M12 (including M2.5 and M3.5), which is how metric threads are shown.

Boxed set of taps and dies with tap wrench and two sizes of stock (for dies).

Sometimes model engineering supply firms, such as Tracy Tools, offer a full set of taps, and also perhaps dies, from 0 to 10BA at an advantageous price. They may only be made from carbon steel but when else would you buy a 7 or 9BA tap? They can come in useful sometimes. Taps and dies in regular use should always be bought, or replaced, in High Speed Steel (HSS). They will not be used at high speed but they are stronger and will keep their edge for longer. The sets to which I refer are of loose taps and dies and not boxed sets, which come complete with stocks and tap wrench. Your spare cash would be better spent on other things

DRILLS