I've been not real satisfied with the quality of my larger diameter 3/8" tubing bends. So 2 or 4 weeks ago, I can't really remember, I scraped together some parts and a loose plan. The rough idea was to try and use v-belt-type pulleys as bending dies and build a bender that would accommodate multiple pulleys so that I could do a variety of bend radii. At that point I was pretty sure I had no idea what I was doing and that the whole thing would be a colossal waste of time and money. But I've never been one to let practicality stand in my way, so I forged ahead.
I've been goofing with it, little by little, in my spare time. Here's the basic frame, that's intended to be clamped into a bench vise . . .
Here's the bending handle . . .
So long story short, I was able to put some time into the project this weekend and I finished it tonight and faced the moment of truth. For the record, I didn't really expect it to work. Reason being, I bought die-cast zinc pulleys. I was pretty sure that the bending pressure would bust the flanges off. But stronger pulleys are harder to find and way more expensive, so it made sense to start with the cheap ones, figure out if they would hold up, and go from there. Thing is, if they work, I can tool up for a variety of bend radii for not a lot of bucks.
Here's a series of pictures that I hope is fairly self-explanatory. If not, just holler.
I'll be damned. The equipment held up and the bend came out looking pretty good. It's a little assymetrical, not so much that you could tell with the naked eye. Most importantly, the flat spots at the start of the bend are gone. Pretty sure I can live with this. Wow. I actually built something that works. Far out.
Scary thing is, now that I have a tiny bit of confidence, I'll be putting together all kinds of crazy shit.