People recommend the “double” split jaw clamps, but I have been able to bend stainless with just the singles. I had to change some 10’ diameter down to a bit over 9’ and I connected 2 sections together with clamps and bent them down to the diameter I wanted, then I trimmed the ends and connected the 2-section pieces together and bent them again (mostly where they joined), there was some minor trimming of one rail after that, but pretty darn close. I removed all screws from the track (Aristo) except for one on each rail in the center of each section.
Be sure you put “open” the bender pretty much all the way, and then tighten down… many first timers do not get the bender on the right side of the rails. Each rail basically has 3 wheels, 2 on one side, and one on the other side.
Which side of the rail is the 2 and which side is the 1 is whether you are tightening the curve or loosening it. If you put the bender on, you will see the force comes from the single moving wheel, so the single wheel on the “inside” of the curve will bend it more, and the single wheel on the outside of the curve will straighten it.
Most people’s difficulties come from either not straddling the rail with the 3 wheels properly, or having it on the wrong side (turned 180 degrees) so that they are straightening instead of bending.
I suppose a video would help, for some people this is really obvious, and for some others, it just does not “click”.
Greg