Roof patch causing warp / oil canning
I am fixing an old CB antenna hole in my roof. The hole was in the center of the cab and I cut a 2" x 2" square to patch in with new metal.
About half way through tacking, I realized I had some major oil canning going on, and a hump on the sides and a valley on the top and bottom. The hump was about 1/8" up and the "valleys" also about 1/8" deep. I tacked fairly slow, 4 or 5 at a time and I don't think heat was the issue. These issues extended almost a foot around my patch in all directions.
I decided to cut out what I had put in and everything settled back to where it needed to be and there is no warp.
What did I do wrong with this patch, and how to I weld in this piece without the warp and oil canning?
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1972 C20
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