- Joined
- Jan 1, 2014
- Messages
- 233
Recently made a backing plate for a 5" 3 jaw chuck that will share duty on my RT and my SB heavy 10. Made a thread gauge to replicate the spindle nose precisely to use in making the backing plate. My new backing plate got a very good fit on the thread and gave it a .002" fit counterbore to shoulder. Only wanted .001" to .0015" clearance but polished it a bit too much and got .002".
Just for kicks I measured the counterbore on the small and large faceplates and the backing plate on the 6" Cushman chuck. All original SB equipment. What a surprise. They all had .022" clearance. I thought the shoulder behind the thread would be the major factor in centering anything on the spindle, but it appears everything centres on the thread.
Anybody else wonder about this?
Canuck75
Just for kicks I measured the counterbore on the small and large faceplates and the backing plate on the 6" Cushman chuck. All original SB equipment. What a surprise. They all had .022" clearance. I thought the shoulder behind the thread would be the major factor in centering anything on the spindle, but it appears everything centres on the thread.
Anybody else wonder about this?
Canuck75
Last edited: