I had some extra pipe, so I tried to see how far I could bend before kinking. I started to get kinks at about 65 degrees, but I found that if I stopped at 45 degrees and re-oiled the die 3 or 4 times as I bent it further, I could get good bends up to 90 degrees. The pipe always springs back a bit when the die is released, so I think the difference is letting the metal relax by releasing the die and bending in small increments when going beyond 45 degrees.
Matt
