I wanted a method so I could bend the tubing to the shape of the door opening while at the same time, keep the bend aligned with the longitudinal axis of the tube to avoid having a warped frame.
With this jig I was able to secure one end of the tube with a clamp while I kept the tubing in contact with the plywood bottom while wrapping it around the frame. I screwed small sections of wooden dowels slightly inside the outline of the door opening.
I used a rubber mallet to help form the tubing while it was being bent aroung the doweling. Tweaking the tubing to just the right shape was aided by mounting the head of an electrical conduit bender in the bench vise. After forming, I slipped a solid rod into the ends of the tube and welded it shut.
