Ron,Terry: after about a year or so of running with the case hardened gears, I had a tooth break off one of the gears. That tooth went through most of the gear train and wiped out most of the rest of them. I machined another set from 1144 . Ten years later, the second set has held up very well. Like you said, one overhardened tooth was all it took to make a mess. Live and learn.
Peter,Hi Terry. What is your procedure for verifying tooth depth of cut on these little gears? For example do you zero contact the cutter to the stock, in-feed X amount according to the book value & that's it? Or maybe cut some teeth on either side of the stock at some slightly shallower depth, then (somehow?) measure & adjust in=feed vs. the target from there? I've never done any, hence the question.
So the conclusion on material is to use 1144 SP and leave it at that unhardened - no heat treating of any kind?