Stall torque on this would be 15N-m. Can a 5/16" shaft with a 3/32 key hold up to it?
Or, if you have any better ideas, I need to get a 13 tooth 20P gear onto a shaft. And I have to do it quickly, soon, and without too much trouble (I’m going to say that LN2 would probably be too much trouble, as would TIG welding).
Knowing the problem, I would tell you to simply drill it to 3/8" and chamfer the inside of the gear, weld it, and then machine it back down to the initial size.
Do you think it would need to be TIGed or could it be MIGed?
You could get away with mig’in it
AH! Whats with the welding of gears! Key the shaft and the gear. It will be fine at 15N-m. We had gears in 2004 that were 7" in dia and were under ~240N-m (I believe, could be higher) and we had those on a 1/2" shaft and they were fine with a 1/16 key. You should have no problems with the 5/16 shaft and it would be easier on repairs if it wasn’t welded.