Welding for Vehicle Restorers E-Book

Bruce Macleod

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

Veröffentlichungsjahr: 2020

Beschreibung

The techniques used in the welding of thin sheet metal as used on vehicle bodies are vastly different to those used in welding heavier structures. This book covers the various methods of welding used to make and repair sheet metal body panels. Whereas some forms of welding are straightforward, others require a significant amount of skill. The important thing for anyone wanting to achieve a good finish to body repair work is to start with the correct techniques: skill then comes with practice. When restoring a classic car of some value, it is worth putting the time and effort into becoming skilled in the use of all the techniques covered in this book in order to achieve a professional finish to your work. With nearly 200 colour photographs and illustrations, this book lists the equipment and materials required to achieve a successful outcome. It describes the different methods of welding and how to choose the correct method for the job and provides step-by-step practical guidance to achieve a professional result. Finally, it focuses on the welding of mild steel and aluminium alloy, with some reference to the welding of brass and stainless steel sheet metal.

Leseprobe

WELDING FOR

VEHICLE RESTORERS

WELDING FOR

VEHICLE RESTORERS

Bruce Macleod

First published in 2020 byThe Crowood Press LtdRamsbury, MarlboroughWiltshire SN8 2HR

[email protected]

www.crowood.com

This e-book first published in 2019

© Bruce Macleod 2020

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

ISBN 978 1 78500 682 1

DisclaimerSafety is of the utmost importance in every aspect of an automotive workshop. The practical procedures and the tools and equipment used in automotive workshops are potentially dangerous. Tools should be used in strict accordance with the manufacturer’s recommended procedures and current health and safety regulations. The author and publisher cannot accept responsibility for any accident or injury caused by following the advice given in this book.

CONTENTS

DEDICATION AND ACKNOWLEDGEMENTS

INTRODUCTION

CHAPTER ONE: HEALTH AND SAFETY

CHAPTER TWO: EQUIPMENT

CHAPTER THREE: GENERAL PRINCIPLES OF WELDING

CHAPTER FOUR: METALS

CHAPTER FIVE: SPOT WELDING

CHAPTER SIX: METAL INERT GAS – MIG

CHAPTER SEVEN: TUNGSTEN INERT GAS – TIG

CHAPTER EIGHT: FITTING PANELS

CHAPTER NINE: FINISHING WELDED JOINTS

GLOSSARY

FURTHER READING

INDEX

DEDICATION

This book is dedicated to the memory of my father, Iain Macleod.

He was one of the last of a generation who trained in the craft of coachbuilding whilst it was a current method of production for bespoke vehicle bodywork in Britain. He was also passionate in passing on these skills to the next generation.

ACKNOWLEDGEMENTS

Thanks to Sarah, my loving wife, for her support and encouragement and her time spent reading through the draft and correcting my poor grammar.

Thank you also to my learned friends Peter Dalrymple and Will Simonson, who took the time to read through the draft and for their suggestions to help it all make sense.

Thanks to Michelle Cooke for her help in correcting errors and taking photographs when needed.

The images used in the book are mostly drawn from my archive as well as various external sources. Special thanks to Steven Booth, who took most of the photographs required to illustrate the techniques. Thanks to R-Tech Welding for supplying the images of some of the equipment shown.

INTRODUCTION

ABOUT THE AUTHOR

The author, Bruce Macleod. STEVEN BOOTH

I began my career in the late 1970s as an apprentice engineer with a machine tool manufacturer. It was here that I learnt to make things to precise dimensions by hand and using precision machinery.

My main interest was in hand-making things, so following my apprenticeship I went to work for my father, who had trained as a coachbuilder from the age of fifteen. At that time, my father was running his own business restoring and hand-making body panels for the Jaguar XK range of vehicles.

This is where I first learnt to weld on vehicle body panels, restoring original bodyshells as well as making new panels, initially welding mild steel panels before progressing to welding aluminium alloy and stainless-steel panels and more uncommonly used materials such as brass, copper and titanium alloy.

During my career, I restored numerous vehicle bodies, working in a variety of materials and construction methods. I have also built complete new bodies from scratch in mild steel and aluminium alloys, from replica early coach-built alloy-bodied cars to later post-war all-steel bodyshells.

Possessing a comprehensive experience in all aspects of vehicle body construction and repair, as well as qualifications in joinery and tool-making, I became a highly regarded authority in my craft. Through the car body restoration courses that I have been running for over two decades, I have trained countless professionals and amateurs in the making of body panels and the restoration of original vehicle bodies.

OUTLINE OF THE BOOK

The text of this book concentrates on the welding of mild steel and aluminium alloy, which are generally used for vehicle body panels, with some reference to the welding of brass and stainless-steel sheet metal used for trim panels on older vehicles.

The result of welding is very different to soldering and brazing. When welding, two pieces of metal are joined by both parts being melted to form one single piece of metal of equal strength. When soldering and brazing, two pieces of metal are joined by the inclusion of another metal. This added metal has a lower melting point than the metal being joined together and therefore creates a weaker joint. Welding is therefore the far superior method to use in forming a strong joint between metal parts.

Restored 1952 Jaguar XK 120 fixed-head bodyshell.

This book covers the various methods of welding used to make and repair sheet-metal body panels. It does not cover the welding of cast materials, as this involves vastly different methods of working and is best done by a specialist, as the knowledge and equipment needed to carry out an effective repair is beyond the means of most vehicle restorers. The welding of higher carbon steels used on more modern vehicle bodies is also not covered. Oxyacetylene welding methods are not included either, as these have been largely superseded by Tungsten Insert Gas (TIG) welding. The welding of thin sheet metal requires different techniques to those used in the welding of thicker metal plate, bar and tube.

I have set out to explain as simply as possible the methods, materials and equipment I have found to be most useful in my career. The process may seem a daunting prospect for the reader, so although this book aims to be a helpful guide to those seeking to weld sheet-metal panels in a professional manner, I cannot overemphasize enough the benefit of attending a hands-on training course to learn these methods. This has proved to be the best way to understand fully the principles and to gain the necessary skills in the shortest time.

Where some forms of welding require minimal skill level, others will require a significant amount of practice to become skilled at carrying out the techniques effectively. When restoring a classic car of some value it is worth putting the time and effort into becoming skilled in the use of all the techniques covered in order to achieve a professional finish to your work. The essential equipment required for this work is minimal, so even the novice welder working from home can achieve a professional standard of finish if using the correct techniques.

There will be a degree of repetition in and among chapters. This is necessary to reinforce certain principles that are critical to the processes.

TYPES OF WELDING USED ON CLASSIC VEHICLES

Early car bodies were of a simple design that had no welded joints. The body panels were either nailed to wooden frames or riveted together to form larger structures.

Oxyacetylene welding and brazing were initially used to join sheet-metal panels. Gas-shielded electric-arc welding and electrical resistance spot welding were developed as more complicated steel and aluminium bodies were produced. The first monocoque, or chassisless, car, which made full use of electrical resistance spot welding in its construction, was developed by Citroën in 1934. Gas-shielded electric-arc welding in the form of MIG (Metal Inert Gas) and TIG were developed in the 1940s. Spot welding has remained the most prolific means of joining sheet-metal panels due to its simplicity in application and the fact that it requires the least skill in its use.

Early coach-built car body consisting of a timber frame, which is panelled in aluminium alloy and sits on a heavy chassis.

Citroën Traction Avant. This was the first monocoque, or unity, body used on a car. The body design made full use of resistance spot welding in its assembly. MARC VORGERS

MIG and TIG welding require a greater level of skill in their operation, which is acquired by practice in the use of the necessary techniques. Welding using these techniques demands patience, good eyesight and quick reactions. Control over the welding torch is critical to the process; stimulants such as caffeine are best avoided as they will impair your ability to control the torch smoothly.

The following chapters cover the tools and techniques required to carry out welding for the restoration of a vehicle body to a professional standard and in the most efficient manner.

 CHAPTER ONE  

HEALTH AND SAFETY

Health and safety should always be taken seriously, as severe injury and long-term health conditions can result from a lack of awareness and discipline in using protective measures. To reduce the risk of harm to yourself and others, it is always necessary to understand the risks and to use the appropriate protective equipment. It is important to develop safe working habits, as a momentary lapse in concentration when working on vehicles can cause serious injury. Tiredness plays a part in many accidents, so avoid carrying out any operations using power tools or other dangerous equipment when feeling fatigued. Working alone increases the risk of harm, as you are more likely to lift something that is too heavy for one person. You may also be unaware of other incidents in the workshop, such as a fire starting, if you are concentrating on a particular job. The environment you are working in can create risks, as many household garages have poor floor surfaces, leaky roofs and outdated electrics, all of which increase the chances of an accident occurring.

Always perform a quick visual risk assessment before carrying out any work on a vehicle so as to reduce the risk of injury or harm. The appropriate PPE (Personal Protective Equipment) should be used in order to reduce the risk of harm, as there are serious health issues that can arise from welding on vehicle bodies caused by:

•fumes

•heat

•electric shocks

•intense light created by the welding process

•sharp edges to metal panels

•trip and slip hazards

•movement of heavy objects.

Grinding metal is also a common cause of injuries arising from:

•sparks

•dust

•projectiles

•noise

•vibration.

List of equipment

The following PPE equipment must be worn:

•fume mask – designed to filter out metal fumes

•gloves – heat- and cut-resistant

•welding mask – of a type that is specific to the welding process

•face shield – polycarbonate full-face screen

•ear protection – ear defenders or ear plugs

FUMES

All paint and electroplating should be removed from the surface of the metal panels to avoid toxic fumes being produced when these are burnt. A fume mask should be worn, or fume extraction used, where there is any risk of fumes being produced during the welding process. Avoid welding close to rubber seals or other combustible materials that are likely to give off noxious fumes when heated.

Fumes created during the welding of metals have been found to cause cancer and there are no guidelines at present as to what is a safe level of exposure. An air-fed mask is the best option if carrying out any significant amount of welding.

A range of leather gloves used for welding. Left to right: rigger glove; TIG welding glove; and heavy-duty MIG welding glove.

HEAT

When welding, gloves should always be worn to protect hands and wrists from burns. It is also necessary to protect arms from any burns that may be caused by weld spatter or contact with a hot panel by wearing suitable clothing. Short-sleeved shirts and short trousers should not be worn whilst welding or working on vehicle bodywork.

Gloves used for MIG welding should have a high level of heat resistance with long enough cuffs to protect the user’s wrists from burns caused by weld spatter that is given off from the process. TIG welding gloves require some heat protection, though need to be flexible enough to operate the torch trigger effectively.

ELECTRIC SHOCKS

Welding machines pose a serious risk of electric shock. Never use in wet, damp or high humidity conditions. Ensure that all cables are kept dry and in good condition. Machines should always be connected to the mains current through an appropriately rated electrical circuit breaker.

It is not advisable to carry out any welding outdoors due to the risks of electrocution and the likelihood of dispersion of shielding gas caused by draughts, as these will result in a poor-quality weld.

Polyurethane-coated gloves should be worn when using chemicals to protect hands from chemical burns and ingestion of harmful liquids through the skin.

INTENSE LIGHT CREATED BY THE WELDING PROCESS

It is important to protect your eyes. The flash of light from the welding process may cause temporary blindness and long-term sight problems if subjected to regular exposure. A suitable face mask is an essential piece of equipment for use during welding. There is a range of varying shades available depending on what type of welding is employed and the amperage used; a higher amperage will produce a brighter flash during welding, requiring a higher level of protection. Metals such as aluminium are highly reflective and a brighter flash will be experienced during the welding process.

There is a wide variety of welding helmets available. For MIG welding, a helmet with a light reactive lens is best, as this enables a clear enough vision of the joint prior to starting the weld. For TIG welding, a helmet with a passive lens is more useful; this lens is always shaded, but has a non-shaded clear area at the bottom of the screen. This clear section of screen enables the welder to see plainly the tightness of the joint before attempting to weld panels together. More detail will be covered on the different masks used for each process in the relevant chapter.

SHARP EDGES TO METAL PANELS

Suitable gloves that offer protection from cuts should always be worn when handling sheet metal. Gloves are available in a wide range of different designs and materials. Some offer more protection against cuts; others more protection from burns or a better grip. The best material that I have found to offer all-round protection and give a reasonable degree of grip is leather. The standard leather rigger glove, which has a safety cuff to protect the wrist, offers better heat protection than thinner welders’ gloves. Their disadvantage is in having less control over the torch button. The best of all worlds is to use a rigger glove on the hand holding the panel being welded to protect against burns, and a thinner leather glove on the torch hand to allow for more control over the welding control switch.

CHEMICALS

Chemical-resistant gloves must be worn when working with acids, thinners or paint to protect against the ingestion of chemicals through the skin and to avoid contamination of other surfaces.

A full face screen should be worn to protect eyes and face from splashes and a fume mask should be worn to avoid breathing in harmful fumes.

TRIP AND SLIP HAZARDS

Cables from extension leads, earthing leads and welding torches create trip hazards and should be kept as tidy as possible and put away when not in use.

Any dust produced during the grinding of metals creates a slippery surface when it falls on to a smooth concrete floor. Sweep up dust and filings at regular intervals to reduce the risk of injury from slipping on any debris.

MOVEMENT OF HEAVY OBJECTS

Gas bottles should ideally be stored securely in a mobile trolley to ensure that they cannot be accidentally knocked over and in order to avoid physical injuries that can be caused by lifting or moving such a heavy object. If free-standing, they need to be chained to a wall or a permanent structure. A falling gas bottle presents a risk of crush injury and harm from high-pressure gas that could be released if the valve is damaged or broken off.

Ensure that any vehicle being worked on is adequately supported and that the bodyshell is not able to fall over whilst pushing or pulling against it when fitting parts.

Gas bottles should be secured to a bench or solid structure to avoid the possibility of them being accidentally knocked over.

A small fire extinguisher should be kept close to hand when welding, as combustion of materials is an ever present risk, particularly when working on a vehicle body.

SPARKS

A serious risk of fire is always present around any welding activity due to the high temperatures attained and the sparks that may be created by the process. Keep a suitable fire extinguisher close to hand, particularly when welding on a complete vehicle that will contain a high proportion of combustible materials.

Oily rags are a common source of a fire starting, as the slightest spark thrown out from the welding or grinding process can cause these to combust. Keep any combustible materials or chemicals in a sealed container to avoid this problem. Welding and grinding should never be carried out near fuel lines or tanks. These should be emptied and purged with Argon gas to avoid any possibility of combustion.

DUST

A suitable mask that is designed to filter out fine dust particles should be worn when using an angle grinder or sanding machine. The adhesives that are used to bond sanding particles to their backing are highly toxic and will be emitted into the atmosphere during the grinding or sanding process. Lead body filler, which is used on older vehicles, is particularly harmful when being sanded or ground, as it is emitted into the atmosphere as fine dust that can be inhaled. Paints used on older vehicles will contain compounds that are toxic and are particularly harmful when turned into a fine dust that is then readily ingested. Protect yourself and others around you from inhaling these particles by the use of adequate dust extraction and by wearing a suitable filter mask that seals effectively on to your face.

Use a face mask that offers suitable protection from dust particles when grinding (on left), or fumes when welding (on right).

A full-face screen provides the best protection when using a powered angle grinder, which can throw out sharp objects at high speed. Goggles that seal to the face should be used to protect the eyes when general dust is present.

When creating dust, your eyes need to be protected from harmful particles by wearing ski-type safety goggles that seal on to your face.

PROJECTILES

A full-face polycarbonate shield should be used when grinding metals to avoid sparks causing burns and irritation to your eyes and burns or cuts to your face. Fast spinning machines such as angle grinders can throw out particles of metal at very high speed that may cause serious injury to unprotected skin. Protect your whole face from these by using a full-face shield. Be aware of the risk to other people around you, particularly when using an angle grinder.