chuck spares

After a few days away to attend an interstate funeral I've finally got back to repairing my chuck. I've turned the grub screws to matching lengths, and now need to turn the groove/neck which engages with the fingers on the back of the chuck jaws.

Being a relative newbie I'm not sure how to go about it. I've learnt from past experience that driving a wide tool directly in can be hazardous to one's health, so a narrow tool is the way to go, but it needs to be stiff enough to not be disturbed by the threads on the grub screw as it is presented to the work .

Should I machine them off first using a different tool? (I'm assuming I should but happy to be corrected)

Should I make several overlapping full depth cuts, or shallower cuts from side to side to the required width of the groove/neck?

The grub screws are very hard, probably HT steel, so any tips on making cutting easier using carbide-tipped tools? My lathe is not set up for coolant so I usually turn things dry when using tipped tools.

I wrapped some copper shim around the screw to protect the threads (brass, tin or alloy would do), held it in the 3 jaw chuck and cut the groove with a parting tool, cut to depth then adjust width to suit. The HT screws cut OK with sharp HSS tools. Dave

Geoff

I made a mandrel of 1" round bar, drilled through and tapped the thread of the grub screws. The screw to be machined was adjusted to protrude the right amount, and locked in place by another screw inserted from the other end. Mandrel in 3-jaw chuck as usual

Turned off the unwanted threads with a wide parting tool in the rear toolpost, one at a time, then smoothed off at the correct diameter.

Job done, mounted each grub screw in the 3-jaw, faced off the end, measured the required distance to the groove, made one deepish cut with a parting tool then advanced the tool progressively by about half it's width each time to take successive cuts to the required width of the groove. Repeated that until the groove was the required depth. Then did the same for the remaining 3 grub screws. Total time required about 1 hour, probably could be done faster but no need to rush it. HSS parting tool worked fine, no lubricant required, nice smooth finish for the chuck jaws to bear against, very happy with the outcome. 4-jaw now back in operation.

Thanks for the assistance.