Snazzy. Is the shifter shaft hardened?
I remember one of our mentors dislike ball shifters, because his experience with them in the past has been that the balls wear out the inside of the output shaft. Can you cross-section it on one of the ball holes to see if that is the case?
From what it looks like, all you’d need is a 3-axis mill and lathe. Turn the sucker down, mill the two holes and set up the piece in a rotary table to make the hex end.
What was the rationale behind not adding more ball’s for each gear to make engagement faster when you shift? Also, what is the benefit of adding ball bearings (my guess at what those depressions in the gears are for) as opposed to the bushings that VexPro sells with their ball shifter gears?
Thanks for posting these pictures; very useful into seeing how this great gearbox was made :yikes:
We used a lathe to turn the counter and bore, then mounted the shaft in an indexer on a manual mill and made the ball cavities and the hex with 2 work holdings.
With a .625” OD this driveshaft is smaller than the drive shafts on the Vex Pro gearboxes. In addition it’s 7075 aluminum not hardened steel, so introducing a fourth ball could have made the shaft susceptible to shear failure. Even if the shaft was strong enough for a fourth set of balls, it would have taken too much time in analysis to prove for the marginal gain in shift speed.
I used bearings in the gears because they’re more efficient than the bushings. They are slightly bigger but that didn’t hinder the design very much.
No problem! Just wait for next year’s gearbox, we have big things in store.
