Welding wasn't bad, but I've done a lot of precision frame type stuff in the past (such as the frame for my ongoing lotus seven project). It's all 16 gauge 1" tubing. I cut everything to exacting lengths before hand so that I could assume their cold length. Put everything together with tacks and corner clamps to start with, did all corner to corner measurements and shifted/adjusted where necessary. It's slow going, but it came up right on the money for the most part. On my lotus frame the corner to corner is within 1/32" over 12 feet using the same method.
There is a smidge of error in a couple places though, which is foolish not to plan for. I adjusted for this using shims I cut up out of one of those auto parts store feeler gauges (like raising one corner of the bed up to level it to the top axis- Feeler gauge strip under the rail mount). |