The idea was to bend some 1" thin wall EMT conduit to make arches for a roof over Joy's big outdoor pottery kiln. The arches needed to be 66" long, and as identical as I could make them without undue effort. So I thought about the tiny little bender I use for fret wire and figured that if I had a really big one, I'd be all set.
It's powered by a small hand crank, and has adjustable roller spacing to vary the bend.
First, I set about making some rollers to handle the conduit, which has an OD of 1.18."
The stock already had the half inch hole in it, by the way.
Outside, I found a piece of heavy steel angle on which I mounted the two pulleys around three feet apart, using a couple of 1/2" bolts and some white grease for lubrication. With the angle clamped in my mill vise, and the drive roller in the quill, I stuck the end of a ten foot piece of conduit between the rollers, and cranked the table in to achieve an appropriate bend.
All I had to do was repeat the operation with the same Y-axis setting and I had three more bent pieces, each with identical curves, kinks and straight sections at the ends.
Joy uses this kiln for soda firing, so in addition to the intense heat coming out of the top, it also exudes corrosive fumes that rust everything in sight. Even stainless gets to looking pretty wiped out. I made the entire roof modular so I could replace parts as they get eaten up, using stainless screws and brass inserts in the conduit.