Originally Posted by Captain Bondo

I have a 1" thick by 4" wide by 2' long piece of aluminum that I use for keeping flanges flat.

It has no holes in it. I clamp the flange to it. Clamps work with any flange- if you use the right clamps they also tend to be less "in the way" of where I am trying to weld. The aluminum conducts heat well and means I can do a lot of flange welding without overheating the flange. It also means I'm not dragging a piece of steel that big (it would be much heavier) around the bench as I move things to get at the welds. Also I use stainless flanges- it's minor but all of that contact with carbon steel isn't ideal.

My jigs are ------ wooden. Yup. Wood.



I only use them for fitup and tacking and they last a long time. I might get fancy and start making aluminum ones since it's a real breeze to weld with the new welder, but wood seems to work KO.

I have made about 15 header off that jig so far.

I prefer to fit everything up, then cut the runners off one by one and weld them up, then weld them back on.

I always wonder if I had a super rigid jig, and I welded everything up solid under a lot of restraint, there was a possibility of having locked in stresses due to distortion.

The wooden jigs acre actualy pretty light and stiff and fast/cheap to make.

edit: Here you can see aforemention bigass piece of aluminum, being it very versatile self: