anybody have shaved marker lights on their car?? Pics??

[dutch]

when you heat metal, even with the smallest change of color, it will shrink after cooling.  When you cool it fast by a wet rag or even compressed air, it will shrink even more.  The shrinking is what causes the distortion.

now, when you make a weld ,you want good penetration and you need a certain amount of energy (heat) to get that done,  so you WILL get distortion, no matter what kind of welding tech you use.    The ONLY way to get rid of the distortion is to stretch the metal back to the surface area it had before welding. 

[dave73chally]

gotcha, very interesting stuff. Now mine are completed, they have been welded and primed well over a month now. Am I in the clear or is there still the possibility for warping if the back bucket was not cut out?

[dutch]

once the metal is cooled down ,there`s no more warpage.   

[rhamson]

when you heat metal, even with the smallest change of color, it will shrink after cooling.  When you cool it fast by a wet rag or even compressed air, it will shrink even more.  The shrinking is what causes the distortion.

now, when you make a weld ,you want good penetration and you need a certain amount of energy (heat) to get that done,  so you WILL get distortion, no matter what kind of welding tech you use.    The ONLY way to get rid of the distortion is to stretch the metal back to the surface area it had before welding.

Depending on the type of welding you do there is a possibility that you will be able to see some outline of the weld on a very hot day. This is especially noticeable on a dark colored paint job. I have heard TIG welding is less brittle and will shrink and expand closer to the parent metal. I try to put a thin layer of lead over it as this is softer and will move with the body movement.

[AAR6BBL]

So Dutch,
School a newbie at this sheet metal stuff.
What do you use to stretch it back? Hammer & Dolly?
Inquiring minds want to know

[Mpdlawdog]

If anybody is interested in making a thread on how to do this correctly...I'd gladly bring my car to you and take pics

[dutch]

on a panel attached to a car, hammer / slapper and dolly usually is the way to go. Most important is the way you fit and weld the panels. If that`s not done perfect ,it will be really hard to evenly remove the distortion.  I gasweld (oxi/acetylene) all panels I make with no filler rod ( unless I blow a hole or something) , in one single pass when possible. Sure, there`s distortion, but welding this way results in a very even heat distribution and therefor very even distortion. Because I try not to use filler rod, the weld itself is just as soft and thick as the surrounding material and not hard to stretch and planish. Now, that`s a bunch of theory.... I would not recomment attacking your qtr panel with a torch unless you know 100% what you`re doing...

[AAR6BBL]

I don't want to hijack the thread, but do appreciate the info.
I remember when I first took an actual welding class they had you welding scraps of sheet just like you describe. Took a while to learn how not to burn through it. I'll stick with my MIG for the sheetmetal on the AAR.
Thanks Dutch