Charlie, do you have Ron Fornier (sp) book on metalworking?

Best hands on one I have ever seen.

get ur sen a good old arc !!!

Charlie,

When you are gas welding a large flat piece of mild steel eg say you might be cutting the bottom off the door of an old Jaguar or something and welding in a new section that you have made, then it is essential that you control the distortion of the metal caused by the heat of the torch.

The best way to do this is to butt weld the joint so that after the repair you will have no overlap and will not be able to see that it has been repaired. It is best to use as little filler rod as possible and to tack the joint every inch or so to begin with.

As you go you gently beat the panel with a hammer and dolly (basisally different shaped lumps of steel), dolly underneath the panel and hammer it on top. This relieves the tension in the metal and allows you to keep the shape you want as you go.

When you have tacked it in place, you can then continuously weld it , but again planishing it as you go.

End result, a perfect repair. This is also how repro wings etc are made ie in sections welded together.

Curved sections of metal can be shaped on wheeling machines and rollers or by panel beating onto a sandbag.

A gas torch and a special hammer and dolly can also be used to shrink metal that has stretched eg after a bump. This involves heating the affected area to cherry red and beating it in a certain way.

As you say gas has many uses. Many people regard it as something of a black art simply because these kinds of skills are no longer learned by body shop workers today.

MIG welding is very crude in comparison.

I suspect that this has more to do with profit that quality!

Seems like the process for repairing most car body damage these days is just to whack a new panel on.

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Curved sections of metal can be shaped on wheeling machines and rollers

I've always known this as an "English wheel".

Maybe it's not called that in England!

Always wanted to have a go at one!

That and the shot bag and hammers. That stuff is a fast-dying art.

Thanks for the tips on the butt welds. I'm pretty handy with a hammer and dolly (even used a shrinking dolly...with mixed success), so I look forward to giving it a try on someone else's Jaguar (pronounced 'jag-whar' here in the states)

Repairs on modern high strength steel and aluminum, must be carried out using the MIG process, as this is something the vehicle manufacturers insist upon. Sadly this means that gas welding is very little used in the modern bodyshop.

A friend with a body shop recently started getting panels that were labeled as being un-weldable.

Being an excellent welder and a stubborn coot, he figured he could weld any metal.

He could not get MIG, TIG or brass to stick to it. Very strange.

Actually, I have recently come across a couple body men who, realizing that welds rust almost immediately, and it is often impossible to get access to the back side of a repair, have taken to using a new generation of "structural adhesives" (glue) to do repairs.

This makes sense to me in certain applications, especially since I have seen a skillfully restored car have the rockers rust out again because the welds began to rust from day one.

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Actually, I have recently come across a couple body men who, realizing that welds rust almost immediately, and it is often impossible to get access to the back side of a repair, have taken to using a new generation of "structural adhesives" (glue) to do repairs.

This makes sense to me in certain applications, especially since I have seen a skillfully restored car have the rockers rust out again because the welds began to rust from day one.

You can get weld through primers that are supposed to prevent rusting. I've never used them myself so I can't really comment on how effective they are.

Interesting debate

Mig tig gas or arc. Lot of expert opinions

The best motorcycle welder there is is a gentleman called Ken Sprayson, every year he is at the Manx Grand Prix and TT races set up in the paddock in a unit sponsored by Air Products welding anything and everything the racers (from back of van club racers to full works riders) require from alloy and magalloy crank cases through to steel frames including extending alloy tanks and similar.

Every time I have seen him working there is a cue at his door carrying everything to do with bikes for his attention . I have never seen him use anything else but gas. If its good enough for him its good enough for anyone!

Ken Sprayson used to be employed by Reynolds making racing frames.

Edited January 15, 200521 yr by g4321