Hello,
I agre with Twin Turbo. I´ll make a short list of how I think it should be done to avoid warping.
1. Build a frame jig. Makes measuring easier and keeps the frame fixed.
2.Take accurate measurements before welding, after welding and after remowing the frame from the jig
3. To avoid problems with the welds, sandblast or thoroughly grind the frame. (does not prevent warping but will give higher weld quality).
4. Weld short distances at a time, maximum 3-4".
5. Always put the next weld "opposite" the previous. With this I mean that if you have put a weld on the topside of the frame you should put the next weld on the underside, at the same position as the top weld. This procedure will make the last weld counteract the tensions induced by the previous.
6. Put the "paired" welds on different locations on the frame the whole time. This spreads the tensions over the whole frame instead of concentraiting them in one spot.
When my frame was finished I removed the supports except the ones in the front and rear. This allows the frame to more or less "float" and if there are some tensions in the frame you will see it in your measurements. When the last supports are removed you can check if the supports move in relation to the frame. If not, you have not induced much if any tension to the frame.
Worked perfectly for me. I have seen a few frames in different threads on the net welded without any support on the bare ground. It is not something I would recommend. However, if I remember correctly, the Chevy power manual says nothing about welding the frame in a jig. It just says, fully weld all seams... Correct me if I´m wrong.
Regards, Daniel
