3/4 x 8tpi acme thread nut

Hi

I was wondering if anbody on here could cut me a 0.750" x 8 tpi leadscrew nut in tool steel. (I can supply the steel) I want to use it to clean up the threads on myford 254 imp. leadscrew. The screw is not worn as such but it has some thread edges deformed . thank you

forgot to say it is left hand

Edited By David Walker 16 on 07/09/2022 19:38:34

You might consider shaping a single point acme form tool from HSS or silver steel. Use it as a hand chaser with a suitable rest and the leadscrew held in the chuck and supported by a tailstock centre, on lowish speed.

That's how old-timers cut some threads.

thanks Clive that a sound idea,maybe job for tomorrow

Rather difficult to make in tool steel, but there might be another way. With an indexable external threading tool an an 8 ACME insert, the leadscrew could be cleaned up simply by chucking it up in sections with tailstock support, and letting the insert pull the saddle (carriage) along about 8" at a time before re positioning it.

I successfully added 4" of 8 ACME thread to the Tom Senior Xaxis leadscrew to allow fitting backlash adjustable nuts. After cutting the new thread, I had to cut the entire length to match the centre part which had some wear or the antibacklash would not have worked. It was done in several sections with as much tailstock, fixed and travelling steady support as I could manage. That leadscrew was twice the lathe centre length.

Your leadscrew could be deburred in short sections close to the chuck using any suitable lathe tool before running the threading insert along.

thanks, another good idea. Ive ordered a acme thread gauge so as to grind the tool accurately. Will let you know how i get on.

If it is only the thread edges that need a little cleaning up, 28 degrees at that edge would make no difference to the operation of the screw. At present it would seem the most likely outcome of using this rough-edged screw would be the early demise of the half-nuts - possibly driving both forwards nd/od in reverse.

I would not be interfering with the face of the threads, if not required.

If the fault with the thread is confined to the external shoulders, I would stick it in the lathe using backgear and chase the thread with a round file of about 3/16" - 1/4" diameter. The lathe could also skim the 3/4" od of the thread, or a flat file could be used.

I would also investigate the cause of the burrs, they are not usual, most nuts are cast iron or bronze, mazak if an Atlas or Myford.

Edited By old mart on 09/09/2022 14:37:17

Job now done, I used a bit of everybodies ideas starting with the round file and then where it was quite bad I used the HSS single point tool. Leadscrew and halfnut now working smoothly.

Thanks to all who replied, great site for information and ideas.