Lofting - Welding

First published in 2013 by The Crowood Press Ltd, Ramsbury, Marlborough, Wiltshire, SN8 2HR

www.crowood.com

This e-book edition first published in 2013

The Crowood Press 2013

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 authors and publishers rights, and those responsible may be liable in law accordingly.

ISBN 978 1 84797 513 3

Acknowledgements
I would like to thank several people who have helped me tremendously with this e-book; without their help it would have been a lot harder than it was. My niece, Bethany Old, provided the glamour in some of the photographs, which without her input would have been rather mundane. I think all would agree she is easier on the eye than a follically challenged, fifty-something guy with a beard. My son, William Lofting, was a substantial help with the welding photographs, as he is excellent with a MIG welder. I like to think that I taught him all he knows about welding, but he makes a better, and more confident, job of it than I can! He hadnt tried TIG welding until helping on the e-book, but now wants an AC-DC TIG welder for his own use. Thanks also go to Pat Neilson and Michael Davies for the use of their equipment, my wifes aunt, Audrey Peters, who proof read the text for me, and of course my wife Pam, who has helped tremendously with keeping morale high when concentration lapsed. Thank you.

At one time, not so long ago, if you were looking for welding equipment for the workshop there was little choice: you either plumped for an AC electric arc welder some more exotic ones giving DC current were available at a price or it meant an oxyacetylene gas welding plant.

Today things are a little different. Indeed, we are possibly spoilt for choice, for as well as the examples mentioned above we now have MIG welders, TIG welders and Inverter welders, all for reasonable prices with something available to suit most peoples budgets.

If I were to say Go out and buy a cheap MIG welder and practise on a few scraps of steel, you would possibly be able to stick two pieces of metal together after a fashion, but how would you know if there had been any penetration? To be able to weld properly it will help to have some background knowledge on what is actually happening and, of course, safety concerns come to the fore as in all forms of welding today. Burns are a real risk with all types of welding and all forms of electric welding carry the risk of eye and skin damage due to ultraviolet radiation (see ).

The first chapter outlines some of the milestones in welding development through the years that have made it possible to produce a good weld with very little effort. is intended to give an idea of what is actually going on in the weld pool itself and the theory behind it, so we can understand what is happening.

All the various welding disciplines will be covered in separate chapters, starting with setting up the equipment to get you going, with step-by-step photographs of the whole process and examples showing the effects of current settings that are too high or too low and other problems. This will enable you to dive straight into whichever chapter is relevant to your welding needs, with all the information that you require to get you going and able to tackle workshop projects as they arise with proficiency and confidence. Specific safety concerns that are critical to each method will be mentioned in the various chapters, but they are covered in depth in .

As with all things practical, while written theory is all well and good, getting someone skilled and proficient to demonstrate how to go about a task and guide you through your first attempts will save you time and frustration as you get to grips with the practicalities of whichever welding discipline you are learning. A friend or colleague may be able to help, but if they have picked up bad habits then these will inevitably be passed on to you and in your ignorance will be perpetuated. The best help and guidance can be found on courses run at local colleges, some of which also provide evening courses to guide you in the correct ways. Health and safety, of course, will be instilled right from the start. When using gas welding equipment, in particular, things can get out of hand extremely quickly, and knowing what to do instinctively in these situations can keep a minor incident from developing into a major one. As stated elsewhere in the book, acetylene can be unstable and in fact is classed as an explosive, but when treated with proper care and attention it is safe to use.

The last chapter will advise on how to choose equipment for your intended purposes and where to purchase it. There is also some discussion of the quantities of shielding gas required and the costs involved.

Throughout the book will be found useful tables on such subjects as welding rod selection and recommended gas pressures. There are also addresses where equipment, consumables and useful advice can be sought.

The first evidence for welding dates from not long after the discovery that metals could be extracted from ore by heat. Examples of iron items being hammer welded in a hearth are known from before 1000 BC . Under this process the two parts to be joined are heated to just below melting temperature and then quickly hammered together. The extra heat and pressure generated by the hammering enables the surfaces of the two components to fuse and become one.

Forge welding has been the mainstay of welding for centuries.

During the forge welding process, heat and pressure are used to join the parts as one.

One fine example of the ancient craft of forge welding is now at the Quwwat al-Islam Mosque in Delhi, to where it was moved at some point in its long history. Known as the Delhi Pillar, it is reputed to have been forge welded, by hand, from several billets of almost pure iron. It stands 23ft 8in (7m) above the ground with a further 3ft (1m) or so buried below, and weighs in the region of 6 tonnes. It is 16in (400mm) in diameter at its base, tapering upwards to 11in (300mm) with a fancy finial at the top, although it is believed that an ornate figure in the form of Garuda (Sunbird), the Vahana of the Hindu god Vishnu, originally stood on top of the column. According to the Sanskrit inscription at the base, the pillar was constructed during the fourth century AD in honour of the Gupta ruler Chandragupta Vikramaditya. In all the time that the pillar has stood at the mosque, there is little evidence of any rust appearing on the column. While this is a very arid region, it is now believed that this is the result of its phosphorus content, incorporated into the iron from charcoal used in the smelting process. This has caused an extremely thin oxide coating to form, preventing further rusting.