DIY Si
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| posted on 26/9/10 at 10:27 AM |
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Removing distortion in metal panels
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. 
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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minitici
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| posted on 26/9/10 at 11:00 AM |
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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]
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gavin174
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| posted on 26/9/10 at 01:00 PM |
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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
http://www.essexkitcarclub.com
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snapper
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| posted on 26/9/10 at 02:13 PM |
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I thought the welding should be done in small stitches lettingthe panel coolbefore doing the next
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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rusty nuts
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| posted on 26/9/10 at 02:31 PM |
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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.
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dave r
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| posted on 26/9/10 at 04:04 PM |
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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 ?
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DIY Si
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| posted on 27/9/10 at 04:39 PM |
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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.
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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NS Dev
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| posted on 15/10/10 at 10:03 PM |
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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
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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NS Dev
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| posted on 15/10/10 at 10:08 PM |
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quote:
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.
I've been metalworking for a long time and it still happens to me now and again, just how it goes.
Your welds were too long, but even with short ones (never go over 1/2" )it'll still "oilcan" as the americans call it on a big
flat panel sometimes.
You just have to remember that hammer and dolly grows the metal, heat and quench shrinks it
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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DIY Si
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| posted on 19/10/10 at 07:28 AM |
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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!
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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