In this picture you can see our spindle on the right and the original spindle on the left. See how we relieved the threads at the end of the thread and the original spindle did not? We did that because the final thread in an unrelieved thread is the weakest point in the part. That final thread on the original spindle has a sign on it that says "BREAK HERE."
In this picture I noticed the cotter pin hole has not been deburred! Naughty, naughty! Sandwich deburred the hole when he noticed it. It sucks to do after aging as the metal gets much harder! So you need to remember to deburr FIRST!!! You MUST deburr all holes and sharp corners to reduce stress risers.
Notice we carefully radiused the junction from the minor diameter of the thread to the outer bearing surface. The outer bearing surface was machined 0.0003 inch TOO LARGE as precipitation hardening alloys shrink when they are hardened. With our CNC lathe we are able to hold 0.0002 inches so there is no need for grinding the surface if you pay attention to the machine.
NOTE!!!
Notice we made the outer bearing diameter LARGER than the original bearing. We changed the outboard bearing from 0.7500 to a Set-12 which measures 0.8656 inches. The increased diameter spindle helps the devilish spindle flex by making the spindle stiffer--and stiffer is BETTER!
