Having one of these tube kinkers I had been searching on how to make it work and it looks like some of the off road guys have managed to get them to work for bending tube with pretty good results.
http://www.thesamba.com/vw/forum/viewtopic.php?t=230317&postdays=0&postorder=asc&start=20

I may have to give it a try as it is pretty much useless for anything else.
Dale

what about this way lol

http://www.youtube.com/watch?v=GWT3N3m4bE4

[Edited on 27/2/12 by JAMSTER]

wow - i'm going to be making my own exhaust from stainless - i wonder if getting a bender and some sand and lots of 2" stainless will be cheaper than buying the bits i need as pre-bent to weld?

this is a great tip.

I have tried something similar to the link you have posted by putting some half pipe between the rollers and and the pipe to be bent and it stops the rollers denting the pipe, also have used as small a die as possible so the pipe to be bent sits on the outside edges of the die and not sitting inside the die and it has produced much better results. I was however bending some fairly thick wall to start with 3mm I think for a mounting bracket for very large antenna. I think if I remember correctly that I practiced on some smaller thinner wall pipe of 19mm pipe 1.6 mm wall thickness to satisfactory results.
I think if you experiment a little you will achieve some good results as the guys in your link have done.

Those little add on's will not stop thin wall tube from kinking You need to draw the metal through for exhausts or try the sand packed in the tube method.

Ive used the packed with sand method and had no probs.
Cheers,
Bob