Hatz Biplane Association

That's a great tip. Wish I saw it before I welded mine :) I used a piece of 3/4" hardwood with a hole drilled in it for the tube, then the washers clamped either side. The wood burns a bit, gets split to come off, but I still had warping and it took a while to get it perfectly straight. This would have worked better.

Nick

One of the most challenging welding jobs so far for me has been the two large washers on the torque tube - see sheet #18 in the classic plans.
I followed hints on other builder's sites, using 3/4" tubing as spacers, but I had severe warpage in between the supporting spacers.

This is what I ended up doing:
Cut (using the tube cutter, which allows for very precise length cuts) 8 or 9 pieces of tubing, and arrange them around the main torque tube, fasten with a duct clamp:
[attachment=1]tack.JPG[/attachment]

Then with the clamp still fastened, went around and finish welded the joint:
[attachment=0]finished.JPG[/attachment]

Came out much better. Live and learn! Cutting the spacers to the exact length was the challenging part really.