- Joined
- Dec 20, 2012
- Messages
- 9,422
I have a new-to-me Emco Maximat Super 11 CD lathe. It has less than 100 hours on it and works great except for one little thing - the cross slide nut is the wrong part and binds. The original owner never addressed it and now I have to fix it. The stock nut is made of Zamack and is a 14mm X 10tpi BSWhitworth rolled thread and nobody stocks a tap like this anywhere in the world, at least not that I can find. A custom tap would cost well over $200.00 so I'm not inclined to go that route.
I think the lead screw itself is still okay, although I suspect there is at least some wear on it from that nut. Still, I want to try and make a new LH nut from leaded bronze but to do that I will have to screw-cut an internal thread on a new nut on the lathe. As you know, the Whitworth thread form has rounded profiles at the top and bottom of each thread and I suspect it is going to be a challenge to grind a tool like this.
My questions are:
1. Has anyone screw cut a BSW thread before and if so, how did you grind the tool?
2. Would you bother doing this or would you just switch over to an Acme thread? I know I can switch from the 14MM BSW lead screw to a purchased 1/2 X 10tpi LH Acme screw and machine the end to fit my lathe. Then I can make a nut by screw cutting and then chasing with a more readily available Acme tap to get the fit I want.
Any advice would be welcomed!
Mikey
I think the lead screw itself is still okay, although I suspect there is at least some wear on it from that nut. Still, I want to try and make a new LH nut from leaded bronze but to do that I will have to screw-cut an internal thread on a new nut on the lathe. As you know, the Whitworth thread form has rounded profiles at the top and bottom of each thread and I suspect it is going to be a challenge to grind a tool like this.
My questions are:
1. Has anyone screw cut a BSW thread before and if so, how did you grind the tool?
2. Would you bother doing this or would you just switch over to an Acme thread? I know I can switch from the 14MM BSW lead screw to a purchased 1/2 X 10tpi LH Acme screw and machine the end to fit my lathe. Then I can make a nut by screw cutting and then chasing with a more readily available Acme tap to get the fit I want.
Any advice would be welcomed!
Mikey