This is bender specifically made to put a very tight radius bend in 5/32″ brass rod for banjo hooks. The original design was modified from this: http://www.micromark.com/universal-bender,8229.html but required a few revisions to get the desired result. Finally, when I was able to force the rod into a tight radius bend, some would crack. I learned that they needed to be heated with a torch before bending, but don’t have to be bent while hot.
The key difference between this and the little universal bender (besides less “slop” and tighter-tolerance fittings) is the movable round die is a “cam” that can be pivoted (with a 3/4″ wrench) and forced tightly against the stationary die while the bend is being made.
This was also my first exercise with hardening O1 tool steel. There are tons of guides on line covering this topic so I won’t go into detail here. Having the working surfaces hardened may not be necessary for bending brass but I wanted to play with O1 steel and this was pretty forgiving applications for a first try. It went quite well.