Worn nut ACME 10 TPI Thread by 0.500 in.

[Geoffrey OlverParticipant @geoffreyolver67992]

Sharp Mk ll Universal Milling Machine – Town Bent Eng. Co

The mill knee is raised and lowered by an ACME 10 TPI thread X 0.500 in. diameter. The worn nut needs replacing. Does anyone know if the ACME thread is right handed or left handed?

Thanks.

Geoff

[Geoffrey OlverParticipant @geoffreyolver67992]

The worn bronze nut fitted in base of Sharp Mk ll vertical mill tapped ACME 10 TPI X 0.500in.

[Brian WoodParticipant @brianwood45127]

Geoffrey,

I don't know as I don't know the machine but I am pretty sure you can establish which hand the nut is just by looking at the male ACME thread. The convention is the same as for standard screw threads and right hand nuts fit right hand threads.

Regards Brian

PS Welcome to the Forum by the way

Edited By Brian Wood on 07/12/2020 18:29:43

[Pete RimmerParticipant @peterimmer30576]

Look at the screw. If it was laid flat and the threads were angled like a row of keyboard back-slashes thus \\\\, it's a right hand thread. If they look like a row of forward-slashes //////// it's a left hand thread.

Edited By Pete Rimmer on 07/12/2020 18:33:53

[not done it yetParticipant @notdoneityet]

There is little point in replacing just the nut if the screw is badly worn. That needs checking, anyway, so you might just as well check the thread rotation at the same time. It looks like it only needs a screwdriver…

[old martParticipant @oldmart]

Tracey Tools sell ACME taps in 1/2" X10 in both left hand and right hand.

[Dave HalfordParticipant @davehalford22513]

Posted by old mart on 07/12/2020 18:53:20:

Tracey Tools sell ACME taps in 1/2" X10 in both left hand and right hand.

They do , for £10 less than a bronze round nut from HPC

[Howard LewisParticipant @howardlewis46836]

Firstly, Does the handle rotate the screw, and the nut remains stationary, or is it the other way round with the nut rotating around a stationary Leadscrew?

If the nut rotates anti clockwise to RAISE the Knee, when viewed from above, or clockwise when viewed from beneath (i.e. screwing itself UP the shaft, the thread is RIGHT Hand

If the nut rotates anti clockwise when viewed from above, or clockwise when viewed from below, to LOWER the Knee, screwing itself DOWN the Leadscrew, the thread is LEFT Hand.

The handle would normally be expected to rotate clockwise to raise the knee, but this may not translate into clockwise movement of the threads. There could be gears between handle and the rotating parts, so you need to observe the nut and Leadscrew..

HTH

Howard

Edited By Howard Lewis on 07/12/2020 21:31:28

[Pete RimmerParticipant @peterimmer30576]

You don't have to move anyhting Howard. Just look at the male thread. The handing isn't affected by which part turns.

[Howard LewisParticipant @howardlewis46836]

Pete,

I was trying to help the OP answer the question as to the hand of the leadscrew and nut.

If you look at my profile, you will realise that I do know how to suck eggs!

Howard

[BazParticipant @baz89810]

I have just been out to the workshop and checked my Sharp Mk 2 milling machine, the thread for raising and lowering the table is RIGHT hand.

[old martParticipant @oldmart]

Posted by Dave Halford on 07/12/2020 20:54:06:

Posted by old mart on 07/12/2020 18:53:20:

Tracey Tools sell ACME taps in 1/2" X10 in both left hand and right hand.

They do , for £10 less than a bronze round nut from HPC

I would go for the HPC nut, but would check with them first just what they mean by "imperial thread"

[Dave HalfordParticipant @davehalford22513]

Posted by old mart on 08/12/2020 16:44:36:

Posted by Dave Halford on 07/12/2020 20:54:06:

Posted by old mart on 07/12/2020 18:53:20:

Tracey Tools sell ACME taps in 1/2" X10 in both left hand and right hand.

They do , for £10 less than a bronze round nut from HPC

I would go for the HPC nut, but would check with them first just what they mean by "imperial thread"

The thread is in TPI and the diameter is 1/2" so if not imperial what?

[old martParticipant @oldmart]

The thread could be any one of a number of threads measured in inches. Whitworth, Unified, are a couple, but the op wants ACME.

[not done it yetParticipant @notdoneityet]

I am wondering where the OP got the information that it is supposedly 1/2” ACME without actually checking it out.

It could quite easily be a square thread (but ACME would be favourite). I doubt it is anything other than lone of those two but, like the thread direction, it needs checking before blindly ordering something that may, or may not, fit.

My Raglan mill may have a square thread for the knee – it most certainly uses square threads for the other axes.

[Mark Davison 1Participant @markdavison1]

The HPC gears nut is ACME, it say "BS1104"

[old martParticipant @oldmart]

BS1104, it would have been sensible of them to advertise the thread as ACME.

[Dave HalfordParticipant @davehalford22513]

Posted by old mart on 09/12/2020 17:16:03:

BS1104, it would have been sensible of them to advertise the thread as ACME.

Oddly they do say Acme on the sheet for the matching leadscrews.

[old martParticipant @oldmart]

I will be doing some ACME internal threading when the museum re opens, I have to make the tooling, but have the easier task because the thread I want is 1" X 5 ACME LH and the bigger it is the easier it is.

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