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Worn nut ACME 10 TPI Thread by 0.500 in.

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

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Geoffrey Olver07/12/2020 16:52:47
1 forum posts

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

Brian Wood07/12/2020 18:29:06
2742 forum posts
39 photos

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 Rimmer07/12/2020 18:33:04
1486 forum posts
105 photos

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 yet07/12/2020 18:48:04
7517 forum posts
20 photos

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 mart07/12/2020 18:53:20
4655 forum posts
304 photos

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

Dave Halford07/12/2020 20:54:06
2536 forum posts
24 photos
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 Lewis07/12/2020 21:29:39
7227 forum posts
21 photos

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 Rimmer07/12/2020 21:53:53
1486 forum posts
105 photos

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

Howard Lewis08/12/2020 12:45:35
7227 forum posts
21 photos

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

Baz08/12/2020 13:44:04
1033 forum posts
2 photos

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 mart08/12/2020 16:44:36
4655 forum posts
304 photos
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 Halford08/12/2020 18:55:10
2536 forum posts
24 photos
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? angel

old mart08/12/2020 20:32:10
4655 forum posts
304 photos

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 yet08/12/2020 23:12:34
7517 forum posts
20 photos

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 109/12/2020 05:55:04
134 forum posts
38 photos

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

old mart09/12/2020 17:16:03
4655 forum posts
304 photos

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

Dave Halford09/12/2020 17:30:28
2536 forum posts
24 photos
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 mart09/12/2020 18:12:36
4655 forum posts
304 photos

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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