Just got me a rockwell 11" lathe on approval. Even with its problems, it looks impressive next my SB9a.
The shear pin between the gearbox and the leadscrew was asked to give up its almost worthless life at some point, and fortunately it did. Unfortunately, the repair consisted of drilling out one of the loose pieces of it, continuing on into the leadscrew and pushing in a pin with that put a higher value its on life.
Six teeth are now missing from the left hand idler and one from the 'e' position driven gear. A local supplier had a match - 16 pitch 40 tooth
- that wasn't too hard to machine to the right shape, and it was only twenty bucks. It mates ok with the bronze gear on the input shaft, but doesn't with most of the ones it drives. I can't turn it by hand.
Do I have the pressure angle problem? If I mesh the gears in my hands and hold them up to the light, the old ones clearly mate almost perfectly while a new and old together look obviously different.
I can probably special order a twenty degree p.a. gear. How likely is it that's what Rockwell used?
For now, I've milled off the broken teeth, drilled holes and loctited in 1/8" brass rod and filed them. It turns smooth by hand - no vfd yet to try it under power.
How soon do I need to make a new gear? Will this one last long enough to do it? What are alternatives to cutting gears on a horizontal mill? Is it practical to reproduce the gear profile on drill rod, mill it to form a cutting edge and harden it? If so, should it be shaped to be applied at the 12 o'clock position or 3 o'clock (or 9)?
Something heavy, like a chuck, dropped onto the casting that holds the crossfeed dial, broke off one ear and cracked the other. What's the best approach to this problem?
Eagerly awaiting your valued opinions,
Dick Hamm Nashua NH
P.s. There are v/f type vfds for what seems like short money at anythingpc.com. Won't see mine until tomorrow, so this isn't even an endorsement, just a tip.