Acme Die

Hello

Where is it possible to Buy a 3/4 diameter 8 TPI Acme Die, I want to make my own custom made leadscrew for my lathe build, I could most probably use a myford leadscrew but the price for these is terribly high also if I buy second hand it's hard to trust sellers as to how worn it is

Regards

lee

Edited By lee hawkins 1 on 16/03/2014 09:44:53

I don't know if they even exist, but this sort of job really needs to be screw cut.

Tony

Lee,

For a custom build you would probably do better to buy a length of leadscrew from Marchant Dice [or some similar supplier]. Here is their ebay shop.

MichaelG.

Hi Michael,
That looks a very useful link but the description "Trapezoidal Spindle - Acme Ballscrew Leadscrew" seems a bit odd. I thought ballscrew leadscrews had a semi circular section thread.#

Les.

OK,

Thank you for the Advice

Graham, I am not sure why a die should/would produce pitch errors? I have cut some quite large threads in the past that have worked perfectly, admittedly I have only cut short lenghts of Acme threads

I need 3/4 8tpi because I have all and will be using myford cogs/change wheels, I contacted merchant dice, what they have wont work, Kingston engineering want close to £100

Regards

lee

Try Jim Marshall at lathe-parts.co.uk

He sells S/H Myford parts and only sells decent stuff. Remember if you use the leadscew from the tailstock end first that end is never or very, very, rarely used

Hi
Depending what length required ? I would screw cut it from the 8 tpi you already have . I had a pitch error using a die . 1/4 whit L/H it showed up on assy I had to shorten the nut on my small top slide for my Exe lathe
Nobby

Hi

Check out HPC they do an 8tpi ACME lead screw **LINK**

Cheers Michael

Lee,

When I asked Tracy Tools about a die of similar size, which I wanted to clean up a threaded round bar, they said it would have to be made specially. Which made the cost out of reach, beyond the amount you quote from Kingston.

Having said that, Tracy do sometimes have odd taps and dies, so may be worth asking.

Phil

A leadscrew will normally ony wear on one side - threading towards the chuck. If you are making custom just get a used one and use it the other way round. Even if you do end up wanting to do a bit of thread work going away from the chuck you will be on the back end of the original configuration so less worn. Once you have this set up you can always then make a new one on the lathe you have built.

Lee,

I`ve got an old Myford leadscrew & yes its worn in the usual place.ie near the chuck end. However as JS states above you could turn it a*** aboutface. I replaced it on my original ML7 years ago but kept it in the cuminandy box.

So far it hasn`t so if you want it you can have it for the postage/carrier price if you want. I`m assuming you are in the UK.

regards Alan

Alan,

That would be fantastic!, yes I am in the uk, I have sent you a message with address

And thanks to all who posted with help and advice, most appreciated

Regards

lee

Gray,

Given that Lee said he was proposing a "custom" leadscrew for his lathe, I thought perhaps he might be better-off using whatever configuration was readily available.

MichaelG.

.

Les,

Agreed, it does seem odd ... I think we can probably put it down to "poetic license".

I tried their website this morning, but it was down; so I posted the ebay link.

I bought a short length of their "Trapezoidal" leadscrew a while back, and was impressed by the quality for the price. I haven't used it yet, but anticipate making a "finishing tap" from the first few inches.

MichaelG.

Hello Lee Hawkins,

Per your request the link below shows where you can buy a 3/4"-8 Acme thread die. Beare in mind it is a cleanup die only and not meant to cut a thread on a leadscrew, just to chase one to clean it up. As others have mentioned threadcutting it or getting some rolled thread leadscrew stock would be a better way. The dies do exist however, as the link shows.

http://www.mcmaster.com/#2486a16/=r49otj

Cheers JD

Gray,

Thanks for posting that explanation, I know what you mean now.

It's the longer the thread length and the inaccuracy of the rod/bar that would be creating the trouble you describe, longer the rod/bar worse it gets.

I get all sorts of ambitious Ideas when working from a tight budget,

I find myself very very lucky in that on this Forum there are very helpful and kind people,that are always willing to help others out

Regards

lee

I shall probably get shouted at for this but here goes. Cutting a lead screw with a die will probably introduce errors. However does this really matter in the context of the use to which the lathe is being put?

Self act for turning does not care about inaccuracy. Screw threading for model making is usually only short lengths anyhow so again cumulative error down the lead screw is less important. Slight concentricity errors will be taken up in the flexure of the leadscrew.

So as long as the user does not plan on making accurate long threads for positioning I don't see why he should not have a go at it.

That said it's probably a lot of effort for not much return.

Martin

Is the Myford leadscrew not a left hand thread? Good luck finding a die if it is.

I gather you are are building your own lathe from scratch, but using Myford gears etc that will match 8tpi?

Perhaps you could do something like buy a length of all-thread threaded bar at the local hardware store, with 8 or 12 or 16 tpi etc and rig it up as a temporary lead screw with the appropriate gearing to then cut yourself a 8 tpi acme thread in the lathe and make your leadscrew that way.

I am sure this topic has been raised before and if you google around, lengths of leadscrew can be purchased at a quite reasonable price. I remember being surprised at the time how cheap it seemed. But cant find it anywhere!

Personally Gray I agree with you.

A job is always worth doing well but not always worth doing better than you need. As I suggested, I would not take the die cut route but each to his own.

Mostly we all over-engineer at home because it's fun.

Martin

I would certainly not try to cut a leadscrew thread with a die . I can't see it being successful in an amateur workshop. When I have to cut a square or acme thread I grind a HSS vee shape tool to rough cut it to near full depth and finish with a tool of the correct profile. Dies are almost certain to give an accumulated error. Colin