garyt1957 Crank them too far, without a torque wrench, and you may distort the rubber at the bottom of the shaft tip.
IMO, I think this is what is happening all over, with all the broken shafts at the hosel. It's not the shaft's weakness, or the hulkster swings(people think they have) but the concussion(graphite on thin steel) reverberating up through the shaft until it is not supported, causing the cracking.