I have a lot of my uncles tools while he's at dartmouth (HI ben), including a hossfeld bender. Supposed to be the highest of quality, right? I can't ever get it to bend without kinking. Everything is on the proper "bits" and everything is nicely lubed up. From tiny wall to 1/4 inch wall I can't do it. And then theres the instrctional video, where these guys bend solid stock like it's nothing. Whats the trick? I wanna be able to use it while I got it

I've never bent large diameter tube, only brake and fuel line sized stuff, and some 1/2" conduit, but what I know from that (and kinking plenty of it) is that the tube has to fit snugly into the die.

The wall of the die supports the tube wall to keep it from pushing outward as it bends. When the tube has room to wiggle in the die, the walls of the tube will spread outward, and the tube will kink rather than bend. Say you're trying to bend a 5/8" od tube using a 3/4" die. Its going to kink because the die is wider than the tube.

Same applies of the die is too small and the tube doesn't fit into it all the way. You can't bend 7/8" Od tube with a 3/4" die.

For 1/2" tube you need a 1/2" die. 1-1/4" tube needs 1-1/4" die.