Originally Posted by
Duragrouch
Thanks. Seems to make sense. But the Wera keys show relief in middle of flat, but seemingly still go to a sharp 120 degree point; For it to be like flank-drive, I would think the very points of the key would be just a bit wider then 120 (so relieved, no contact), and then a very slightly rounded section between that and the middle recessed "flats". Otherwise, you're still driving by the points. No? From Wera website:
Looks like the hex plus is designed so that more than just the corner makes contact after initial wind-in - the corners are wider than 120° so they look like they have been pushed back, allowing more contact away from the corner, rather than presenting a sharp point that would dig into a good socket but round out a bad one. I just bought a set of these as a result of this discussion, will be interesting to see how they work out.