Morning all.

I've been busy restoring my Sprite recently, but I have encountered a problem or two. When welding in patches, I sometimes get distortion in the surrounding panels. Especially if the patch is near the edge of an existing panel.

Is there a way of shrinking the old panel back into shape? I've heard of a method that involves heating the affected bit of panel until cherry red, knocking the now present dimple out and then dashing it with a wet rag to rapidly cool it.

Is it really that simple? It all seems a bit too easy to me and I fear there is a catch I have missed. Any hints/tips/other methods will be much appreciated.

Have a look at metal shrinking discs.
Lots of videos on Youtube.

Basically a smooth metal disc which fits to an angry grinder and heats up the surface by friction.

Then quench with water and the high spots shrink.

[Edited on 26/9/10 by minitici]

there was a video doing the rounds of heating with a hair dryer or hotair gun.

and then rapidly cooling with a fire extinguisher or dry ice

I thought the welding should be done in small stitches lettingthe panel coolbefore doing the next

Something like Cold Front may help to limit the distortion in the first place . Heating and cooling works for me when I've had to do it.

if anything after welding the panel should need stretching, not shrinking.... the weld contracts and pulls as t cools
are you beating the welds flat or just grinding off ?

Dave,

A little bit of both really. I've not done much/anything really in the way of car body metalwork before, so it's all a bit of a learning curve at the moment.

The main bit I have now fixed with heating with a blow lamp and then quenching with a wet rag along with a little bit of gentle hammer and dollying.

The welds were done in 2-4" strips depending on what I thought I could get away with, but I guess I need to do either smaller welds, or allow longer for it to cool. I suppose I'm being a bit impatient as it was only a small patch on the back of the A post.

Ah well, it's fixed now, but I'll have to try harder to now let it happen in future.

hot shrinking works but god its slow and bloody tricky!!!!

You take out a "PING PONG" dint from one bit and end up with another somewhere else!

Does work evenually though.

I tend to hot shrink the whole area, then tack studs on and pull it back into shape, then dolly it to finish it

slow however you do it though

quote:

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Originally posted by DIY Si
Dave,

A little bit of both really. I've not done much/anything really in the way of car body metalwork before, so it's all a bit of a learning curve at the moment.

The main bit I have now fixed with heating with a blow lamp and then quenching with a wet rag along with a little bit of gentle hammer and dollying.

The welds were done in 2-4" strips depending on what I thought I could get away with, but I guess I need to do either smaller welds, or allow longer for it to cool. I suppose I'm being a bit impatient as it was only a small patch on the back of the A post.

Ah well, it's fixed now, but I'll have to try harder to now let it happen in future.

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Cheers for that advice. It's good to know that I'm at least going along the right lines and that in can just happen at times. Hopefully it won't happen so much if I'm more patient in future!