Making M Type Drummond lathe cross slide leadscrew nut.

[David George 1Participant @davidgeorge1]

With the lockdown I thought that I would make a couple of spare nuts for repairing worn threads in crosslide casting. The thread us cut straight into the casting so when wear becomes to much the only option is to bore out and replace with a phos bronze bush.

Screw cut and tap and check with leadscrew.

David

[David George 1Participant @davidgeorge1]

[old martParticipant @oldmart]

Is that a RH square thread?

[David George 1Participant @davidgeorge1]

Yes Old Mart it's a 1/2 inch OD 10 TPI RH square thread.

David

Edited By David George 1 on 18/04/2020 19:08:31

[old martParticipant @oldmart]

I would have expected a left hand thread with a cross slide. Is the nut attached to the saddle?

Edited By old mart on 18/04/2020 19:29:30

[geoff walker 1Participant @geoffwalker1]

Good idea David.

something I need to do but never get round to it.

When you say screw cut AND tap what do you mean?

Geoff

[not done it yetParticipant @notdoneityet]

the only option is to bore out and replace with a phos bronze bush.

• I would have thought that brass or even (ordinary) bronze, would impart less wear on the lead screw. Very few would consider making a lead screw nut in phosphor bronze.

[David George 1Participant @davidgeorge1]

I made a finnish tap from silver steel hardened and tempered just t make sure i can repeat sizes.

David

[geoff walker 1Participant @geoffwalker1]

Hi David

OK, I'm with you now and I can also now see the tap in the first photo.

So presumably you machine the thread almost to size and skim out a small amount with the tap, good idea.

Have you already fitted a nut to your M?

If so I would be interested to know how you held the saddle then bored out to size for the nut.

Geoff

[geoff walker 1Participant @geoffwalker1]

David

Just had a look at your photo album.

Nice work

Geoff

[David George 1Participant @davidgeorge1]

To fitt the new nut. The saddle was stripped and removed and set up in the mill against an angle plate, picked up the centre and bored through. The head recess was machined at the same time and the screw holes for the retaining screws. The bush was locktited in and screws fitted, job done.

David

[geoff walker 1Participant @geoffwalker1]

Thanks David

I've sent you an email.

Geoff

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