Roger Taylor
Active Member
- Joined
- Apr 9, 2023
- Messages
- 27
- Reaction score
- 30
After cutting the cooling fins on my Crusader 60 cylinder, I used the same hand ground HSS bit for the part-off. About halfway through the hand feed operation, the bit caught ever so slightly, and the chuck studs sheared off dropping the chuck onto the bed as in the attached photo. eighty-five RPM, flood coolant, with the cut as close to the chuck as possible and the carriage locked, I've done this operation hundreds of times. The Harrison M300 13" lathe was Navy surplus and came with a 9" Buck 3-jaw. plus, a large 3-J Hardinge hand wheel collet setup. I have used that chuck for twenty-five years never suspecting that the oversize could put a destructive strain on those cam studs or maybe the heat tread was not correct. Fortunately, at low RPM the only damage was to the studs. Anyway, just a heads up for folks to check stud adjustment and possibly a die penetrant check if any issue is suspect. I have replaced the studs and also invested in a 6" 3-jaw for 80% of my work.
