ACME sizes on machines

[Michael G]

Simon made a comment about how he would like to replace the ACME nuts on his mill which made me think of the screws and nuts on my lathe.
I've made up one new nut and screw but need to do the other soon. I've always single point cut both the screws and the nuts as the taps are more than I want to pay for a single use. However, a 1/2" ACME nut in phosphor bronze is about the limit I can cut (although it is nothing more than serviceable).
On my 'one day' list is to make up appropriate taps (1/2"-8tpi RH & 5/8"-8tpi LH), although that will require about 6 other projects for the necessary tooling to be finished too.
What sizes have others got on their machines? Do you have taps or single point them? If you single point, do you do the screw or the nut first?

Michael

[pipeclay]

I allways cut the nut 1st.

[morrisman]

I'm going to try the DELRIN nut solution..somebody posted the write up somewhere on a forum . You use a heat gun to form the Delrin nut onto a ACME screw .Its worth a try I think..MIKE

[Graziano]

if you are tapping bronze nuts, what about getting a small length of the acme screw in question and making it into a tap by grinding several flutes into it?. I've noticed on carbon steel taps that they have more flutes than high speed steel so as to give more cutting edges. If you made a longer than average tap with a gradual taper and multiple cutting flutes then a steel tap should cut a nut.

[simonl]

I'm going to try the DELRIN nut solution..somebody posted the write up somewhere on a forum . You use a heat gun to form the Delrin nut onto a ACME screw .Its worth a try I think..MIKE

I've read about the Delrin nut solution. Would you need to make them longer to take the forces? Do you think they would last?

Cheers,

Simon

[rodm]

I have used Delrin nuts on an Acme thread on a CNC machine. They don't last long and I would be worried about distortion under a heavy load but you could make a longer nut and that might help. A tap was made from a bit of the acme thread as previously described and the delrin frozen before cutting the thread.

[morrisman]

My Sheraton Ar lathe had worn cross slide and top slide nuts

I tried a bodge solution . I mounted the nuts on a shaft and used a drill to slowly spin them while applying solder internally on the worn threads. The solder solidified in a even layer .

I then used the cross and top acme screws from the lathe and tapped the soldered nuts .

I put it back together . The cross slide repair didn't last long , it was sloppy again after a short period , not a success . But the top slide repair has lasted very well and it is still nice and firm despite a lot of use ! . MIKE