Acme thread

8 tpi is pretty coarse for a 3/8" diameter thread, it might be a bit of a struggle. At 1/16" thread depth plus clearance that only leaves less than 1/4" core diameter. It will probably need to be thread milled, even if you put the clearance on the nut instead of the core diameter.

Can you get away with a finer pitch or greater diameter?

Neil

Tell us more. Length, length of thread, material, why ACME, etc?

Dies are available for purchase (recommend them for finishing a roughed/part formed turned thread). Square threads are often substituted for ACME threads. Do you need a new nut?

HPC Gears can supply a range of items at reasonable(?) prices.

im after a cross slide feedscrew making,for a new cross slide that im getting made,length of cross

slide is 10",and its looking at a 3/8" x 8tpi thread,got to be acme as that was the old feedscrew was

also i dont need the nut as that is in the carridge/apron where the screw will go thru,

i did try a few places and got quoted stoopid prices, 65 quid,50 quid,160 quid, for a 270mm length (this is going off a myford ml7 long cross slide feedscrew)

for a new cross slide that im getting made

It would seem to be a sensible suggestion that the maker of your cross slide supplies the screw?

.

Agreed ... Which is probably why the suppliers list such leadscrews in 'Stub Acme'

http://www.roton.com/Engineering_Data.aspx?line=Acme

Dave: I suggest you check the dimensions of the original thread carefully, before shopping.

MichaelG.

Edited By Michael Gilligan on 03/08/2016 10:25:22

Edited By Michael Gilligan on 03/08/2016 10:26:42

Hi David,

Just to be sure that you're aware, an imperial ML7 cross slide feedscrew is 10 TPI (100 thou per revolution) and not 8TPI.

They're clearly no bargain but are available new, direct from Myford here... **LINK**

Jon

You probably should shop around for some Acme threaded rod. I am sure there has been discussion on here before and a UK industrial supplier was found to be quite reasonably priced. Can't remember the name though. But a forum search for "acme threaded rod" or something might turn it up.

Just for example, and I presume it's wrong side of the pond for you, but McMaster Carr sells 1ft lenghts for not much over $10. See link

**LINK**

.

Quite so, Dave

**LINK**

https://goo.gl/images/9drHAr

MichaelG.

Does not make it any easier.

.

No ... But it does save making the wrong thing.

MichaelG.

Just a suggestion but why not buy a S/H but decent Myford cross slide screw and nut and adapt it ?

You have a lathe. Make one. Lock the cross slide in position and set the topslide at 90 degrees to the lathe axis and use it to feed the cut in. A moving steady will probably be required, but is easy enough to make up too.

+1 for Hopper's method. Square thread is easier to screwcut than ACME anyway, the tool tip is only 1/16" wide, so if the lathe will part off it will cut this thread

On such a small diameter an 8tpi thread will require the tool to be at a roughly 19-20 degree angle to stop it fouling the sides of the thread.

Rather than a parting tool grind a cutter on the end of some round HSS, then rotate it to match the helix angle.

Neil

Neil was right at the start of this thread by suggesting that
this leadscrew would be best milled.

The recently published articles in MEW 241 to 243 show
how easily this is done.

Some editing at the end of the article left out an important
aspect of this operation.
The reasons for the editing are not an issue as i could
probably understand why this may have been done ,the
missing text is as follows.

"when cutting the second of these screws i was not even in the workshop ,i
was in my elderly neighbours (older than me) garden trimming up some
bushes,i doubt that there are many that can claim to have made an acme
screw and done some gardening at the same time ".

Of the five leadscrews that were produced and shown in the article i was only
present while the first one was made .
I was shopping in Asda when cutting this 3/8 by 10 tpi seen here in this photo
in the album leadscrew.

Conventional screwcutting these sort of leadscrews is a redundant operation and
a complete waste of time.
The unit as seen will fit on a Myford 7.

John