woodfarmer
Plastic
- Joined
- Nov 11, 2014
Hi
My 95 year old Holbrook is beginning to show some signs of wear in the cross slide. The leadscrew is worn in the centre part and also the nut has a little bit of wear. Currently the thread employed is 8tpi square, The nut seems to be made of brass.
Looking at it I thought the leadscrew was 1/2 inch diameter but it is in fact 0.556 inch. This has foxed me and I cannot see any reason why 1/2" was not used.
I originally thought to use a 10 TPI Acme tap to make a new nut and acme lathe tool for the leadscrew thread, switching to 10 TPI would reduce the feed a little and if I were to use a 100 segment handwheel would maybe be simpler. I doubt I will find a tap of .556 inch diameter.
Is there any reason I shouldn't use 1/2" ?
I wont need for it to last for another 95 years so am quite willing to use an easy to machine steel for the leadscrew and anything easy for the nut, posssibly even plastic. Five years of light use will be enough for me.
the leadscrew fits into the lathe through a hole and after the screw part (and a bit of unthreaded bar) emerges under the toolpost the only thing it touches is the nut.
so two questions : What would be suitable materials and is there any reason not to use 1/2 inch for the screw thread and nut ?
Thanks for your help
My 95 year old Holbrook is beginning to show some signs of wear in the cross slide. The leadscrew is worn in the centre part and also the nut has a little bit of wear. Currently the thread employed is 8tpi square, The nut seems to be made of brass.
Looking at it I thought the leadscrew was 1/2 inch diameter but it is in fact 0.556 inch. This has foxed me and I cannot see any reason why 1/2" was not used.
I originally thought to use a 10 TPI Acme tap to make a new nut and acme lathe tool for the leadscrew thread, switching to 10 TPI would reduce the feed a little and if I were to use a 100 segment handwheel would maybe be simpler. I doubt I will find a tap of .556 inch diameter.
Is there any reason I shouldn't use 1/2" ?
I wont need for it to last for another 95 years so am quite willing to use an easy to machine steel for the leadscrew and anything easy for the nut, posssibly even plastic. Five years of light use will be enough for me.
the leadscrew fits into the lathe through a hole and after the screw part (and a bit of unthreaded bar) emerges under the toolpost the only thing it touches is the nut.
so two questions : What would be suitable materials and is there any reason not to use 1/2 inch for the screw thread and nut ?
Thanks for your help