- Joined
- Aug 13, 2020
- Messages
- 1,342
I was making some turning tool holders for my CXA QCTP a couple days ago. To get the tool slot perfectly aligned, I decided to cut it on the lathe. I mounted the ER32 collet chuck-block with a 1/2" carbide endmill on the spindle, and the work-in-progress toolholder on the toolpost. Figured a couple passes, and I'd have my slot.
Except, at the end of the cut, the endmill broke through, and the carriage jerked. Then I noticed that there was a 1/4" space between the carriage and measure dial. Tore it down yesterday to find that the crossfeed is held from pushing out toward the operator by a pinned gear on the inside. The pin sheared when the endmill broke through. The fatigue pattern tells me that this break was long in the making.
Best I can tell from, this pin goes from .178 to .192 over the .850 diameter for the gear. I installed a B&S taper pin once in the distant past, but that is the extent of my taper pin experience. I know there are a ridiculous number of "standards" given how seldom taper pins are used, and I don't even know where to start to determine which standard (if any), this 80yr old Sebastian lathe followed. I'm thinking my best bet is to find a modern standard that is just a tiny bit larger.
But, how would I go about that?
Except, at the end of the cut, the endmill broke through, and the carriage jerked. Then I noticed that there was a 1/4" space between the carriage and measure dial. Tore it down yesterday to find that the crossfeed is held from pushing out toward the operator by a pinned gear on the inside. The pin sheared when the endmill broke through. The fatigue pattern tells me that this break was long in the making.
Best I can tell from, this pin goes from .178 to .192 over the .850 diameter for the gear. I installed a B&S taper pin once in the distant past, but that is the extent of my taper pin experience. I know there are a ridiculous number of "standards" given how seldom taper pins are used, and I don't even know where to start to determine which standard (if any), this 80yr old Sebastian lathe followed. I'm thinking my best bet is to find a modern standard that is just a tiny bit larger.
But, how would I go about that?