Warped oil can quarter

[es1758]

I need a bit of help I welded in a lower patch panel on the rear quarter of my 69 and even though I went slow I still managed to warp it and ideas on how to resolve this it is oil canning and don't know if I need to shrink or stretch it.

 

[69roadr]

if its "oil canning" i would assume you need to shrink it. i have seen people using a heat gun on the area, and then cooling it down quickly with cold water.

 

[krowbar]

if its "oil canning" i would assume you need to shrink it. i have seen people using a heat gun on the area, and then cooling it down quickly with cold water.

What he said. Just take your time and don't get it too hot at first. If it doesn't come out get it a little hotter next time or practice first on a scrap piece.

 

[es1758]

Do I heat the high spot and try to shrink it

 

[krowbar]

Try heating around the whole high spot almost to the edge. Less heat at the edges because that heat is gonna travel quick on thin metal.

 

[es1758]

Ok I ll give it a try. The pic below shows it, if I press in on the pink circle the pink "X" will pop out

 

[krowbar]

You need to grind that weld seam down first because that will be putting heat back into the metal which may bring more problems. Make sure when you weld and grind that you put as little heat in one area as possible. When you heat metal and it's constrained then the constraining forces don't let the heat out and you get bubbles and bows.

 

[Photon440]

Get a 'shrinking disk' which fits on an angle grinder and heats up the high spots, and a specialized shrinking hammer to tap down the surface once it's hot. It looks like your welding was done in long passes, it should have been a series of spots a few inches apart, repeated until they joined together. It's still fixable.

http://www.carrepair-1950.com/shrinking-sheet-metal.htm

 

[es1758]

Get a 'shrinking disk' which fits on an angle grinder and heats up the high spots, and a specialized shrinking hammer to tap down the surface once it's hot. It looks like your welding was done in long passes, it should have been a series of spots a few inches apart, repeated until they joined together. It's still fixable.

http://www.carrepair-1950.com/shrinking-sheet-metal.htm

No I did a series of tack welds bouncing around to try to control heat. The longer heat marks are from re heating with a tig torch to tap weld seems as they cooled to stretch them, I read that the weld seem would shrink as it cooled and cause an oil can affect so I tried to reheat small areas and tap them out similar to the sayin "each tack gets a whack"

I will look into getting a shrinking disk, will this allow better heat/shrinking control and will it shrink the metal to the low side of the dent or allow it to relax to its "normal" position. I was unsure if it needed to be shrunk or the seams need to be stretched as they shrunk while cooling

 

[BarrsRestoration]

First thing you need to do is take the welds down flush. The added thickness is tightening the panel and any attempt to correct the oil canning will be hindered by that. Using the edge of a cut off wheel will produce less heat than a grinding disc on those welds. Switch to the disc when you get almost flush with the cut off wheel.
Then see how the metal acts.

 

[snakeoil24]

Tig welding sheet metal is very difficult for most people. You need to beg borrow or rent an oxy torch set up and heat the circle then quench with a cold rag. Grind the weld line with a flap disc and an air gun to keep it cool.