FWIW, my team has had no problems with shafts made from
Thunderhex. We love the stuff because it fits both hex bearings and hex broached holes perfectly, eliminating the "file to fit" step. It also comes with a 0.2 inch center hole that works well for clearance to #10 screws and for tapping 1/4-20 threads. And it machines very easily, leaving beautiful diameter and face cuts with ordinary HSS tools.
It is 7075. I think Paul Copioli or one of his technical staff could provide some background on how they selected a supplier, and what tests were performed. I only know we have never bent or broken it.
__________________
Richard Wallace
Mentor since 2011 for FRC 3620 Average Joes (St. Joseph, Michigan)
Mentor 2002-10 for FRC 931 Perpetual Chaos (St. Louis, Missouri)
since 2003
I believe in intuition and inspiration. Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution. It is, strictly speaking, a real factor in scientific research.
(Cosmic Religion : With Other Opinions and Aphorisms (1931) by Albert Einstein, p. 97)