- Joined
- Nov 29, 2015
- Messages
- 439
I finished up making a replacement cross feed nut today. 660 Bronze 7/16-10 tpi Acme Left handed threads.
I used a 3/8" corner rounding mill to round the edges. Yes, I know I went a little deeper on one side.
I hand tapped it while it was mounted in the mill vise. I don't own a Jacobs chuck that fits the mill...so I used a 3/4" diameter (on the end of the shank) spring loaded center punch in an R8 collet to keep tap straight while tapping. The spring tip (if you don't set it off) will keep tension on the tap as you move down. It might sound precarious but if you set it up right it will be ridged enough to keep you straight. You will have to feed your quill down as you go...since a spring punch has limited movement. Since tapping Acme threads moves a lot of metal I made sure to break the chip every quarter turn. The tap I used was a single pass through tap.
Gotta make the screw for it later on.
Paul
I used a 3/8" corner rounding mill to round the edges. Yes, I know I went a little deeper on one side.
I hand tapped it while it was mounted in the mill vise. I don't own a Jacobs chuck that fits the mill...so I used a 3/4" diameter (on the end of the shank) spring loaded center punch in an R8 collet to keep tap straight while tapping. The spring tip (if you don't set it off) will keep tension on the tap as you move down. It might sound precarious but if you set it up right it will be ridged enough to keep you straight. You will have to feed your quill down as you go...since a spring punch has limited movement. Since tapping Acme threads moves a lot of metal I made sure to break the chip every quarter turn. The tap I used was a single pass through tap.
Gotta make the screw for it later on.
Paul
Last edited: