Originally Posted by Lizer
Ok, back to this thread again. I ended up just getting a full quarter and cutting it down to make my skin.
The test fit was good, got everything screwed down how I liked it. I ended up taking my cut off wheel and cutting the old metal right along the top of the seam of the new metal, making a perfect seam, and butt welded the entire thing. I actually think this way would have been way easier than doing an overlap weld.
Well, I'm here now to deal with the woes of butt welding. Even though I spaced my tacks and let them cool naturally, I've got some pretty serious warpage. One of the pics lets you see it real well.
I went back and reread what puggy offered....on dolly hammering, then shrink. I would like more advice on this. I finished everything up then did not even touch the warpage until I see what is recommended here.
The problem I get with on dolly hammering is it makes a real low spot where I was doing the hammering, even though I'm trying to hold the dolly tight against the back. Am I doing something wrong?
Given what you see in the pics, what would you guys do. The high peaks and low areas are very obvious to feel out.
By the looks of the first photo you didn't skip around at all, that is the problem and why you got warpage. Those welds shouldn't be next to one another like that, they need to be spread out, one at the front, one at the rear, let it cool, one in the middle then one at the rear, let them cool, one at the front then one 3/4 way, then let it cool one a foot back then one between the 3/4 and the rear, skipping all over and letting them cool completely.
Now, you want to grind the welds down to thin them out. You can't do any hammer and dolly on those welds. Be careful and use a nice sharp disc or you will create more heat and possibly more problems.
Shrinking those spots can be tough being you can't get behind with a dolly very easy while you hammer on the outside. Good old heating and cooling with air or water may be the way to go. Do this right at the weld that caused the high spot. A small dime sized spot heated up then cool is all you want. Now without a torch or a stud gun or something to heat, it's going to be tough. This may be a good time to look into a shrinking disc. That is a prefect spot for this tool, you run it over the metal and cool it, it's basically a "Heat block" and you only heat the high spots. http://www.ghiaspecialties.com/
But this may