Myford ML10 metric leadscrew

My Myford ML10 metric leadscrew is a bit worn, so i wondered if anybody had (pardon the pun) a lead on where i can get another , or get one made?

I found new metric half nuts, but finding a new metric leadscrew is another issue

Many thanks Pauly

Edited By Paul Smith 37 on 14/03/2020 19:24:47

Edited By Paul Smith 37 on 14/03/2020 19:26:53

Whooa.look at this

https://www.youtube.com/watch?v=moVDZrYGnyc

All i need some of this bar, now to locate some.

Edited By Paul Smith 37 on 14/03/2020 21:44:50

So ive found these,Im not sure how to find out which one to buy?

**LINK**

Ive measured the leadscrew which is about 15.87mm max width, which i take that to be a 16mm size,but i cant find a 3mm pitch, either 4 or 8.

well thats frustrating..

15.87mm, is, of course, exactly 5/8”🙂. ‘About’ may not be near enough but about 0.1mm is neither here nor there for the diameter of a leadscrew.

.

... which, incidentally, makes my request [posted this morning, here: **LINK**] all the more relevant.

https://www.model-engineer.co.uk/forums/postings.asp?th=135379&p=2

MichaelG.

The 'normal' first recourse for this problem is to turn the leadscrew end for end and use the 'back' face that hasn't been worn much. You have to make new ends of course.

I'm not sure if people are appreciating the advantage for lathes moving from square thread to Acme/Trap with a sloping face. The half nuts can be made with deeper threads firstly to give space for crud but so that the nut engagement can be increased with wear (the grub screws mentioned on the other thread) and adjusted to reduce backlash. If the thread bottoms out on the leadscrew the nuts can be bored out a bit as they should be considered sacrificial. You need to do the adjustment sufficiently often to avoid wearing a ridge on the nuts.

So al in all you haven't got a problem, you just need the right approach.

I’m fairly sure the advent of ACME was to implement easier engagement for lead screws.

Square thread sideways engagement is only possible over the backlash distance, while a tapered thread will have so much more scope for a positive engagement. The other advantages are secondary. Plain feed screws are still stronger, mechanically, when made in a square format.

This thread pivots on what the OP means by ‘a bit worn’. Some use their lead screw to drive in the other direction (rather than moving the carriage from right towards the left). Most threads are not that long as to make the error particularly frightening, I would have thought?

Looking at the other thread on ML10 Leadscrews, it sounds as if a Metric Leadscrew for a ML might be be REAL hybrid.

Possibly made from the same raw material as for an Imperial machine (Makes sense, or they would have to make the mating bearings/ couplings Metric as well, in a smaller volume )

So it could be 3 mm pitch ACME form Leadscrew made out of 5/8" bar!

Curiouser and curiouser?

A bit like my mini lathe, with a 1.5mm Leadscrew but 20 tpi Leadscrews on the Cross and Top Slides!  But the DROs can accommodate that  

Howard

Edited By Howard Lewis on 15/03/2020 15:15:04

Quite common to find metric pitch ACME thread feedscrews on imperial stock material. Makes life much easier for the machine tool maker.

For example the specification of the metric, 5 mm pitch, Bridgeport feed screws is :-

Thread Type single, left hand 5 mm pitch

Major Diameter 1.250" / 1.240"

Pitch Diameter 1.138" / 1.135"

Minor Diameter 1.040" / 1.030"

Thread Class Special

Pitch 0.1968" (5 mm)

Lead Error 0.001" / ft

Mr Bridgeport of course couldn't care less how hard this practice makes it to figure out if used, slightly worn, feedscrews and nuts are actually metric or imperial. Or for that matter new, unlabelled, ones. Standard inch (ish) long thread gauges really aren't up to indicating the 32 thou pitch error between 5 mm and 10 TPI.

Unless you know the cunning method for sorting coarse metric from coarse imperial threads.

Ultimately ACME is a thread form defined by formulae and so is not tied to any specific dimensions or style of dimension. You could do an ACME thread in cubits if you wanted, assuming you could find an official definition of what a cubit really is.

Unlike specific named threads such as M10, 3/8" whitworth et al which are both defined by formula and tied to a specific style of dimensions. Even then although whitworth form is an imperial definition its been metrificated for ISO-7 series pipe threads. Similarly BA is a metric thread restated in imperial dimensions with some minor modifications. This practice always seems to give funny numbers where you don't want then and difficulty figuring out tolerances.

Clive

Ive put up some pictures on this thread **LINK**

So the question is, does anybody know where i can get a new leadscrew made?Its way above my station, ive still got my L plates on!

.Id be ok making the threaded bar fit, but making the thread is another matter.Bearing in mind my lead screw is worn too.

cheers chaps !

.

Good summary here: **LINK**

https://www.dependableacme.com/so-why-use-acme-threads-what-is-it-all-about/

They also have numbers, and printable thread gauges !

MichaelG.

This is another good source of info

**LINK**

Ok ive checked the ML10, it is capable of machining a 3mm pitch thread.Somehow if i could make the cutting tool,what steel would people recommend ?

Im going to have a bash and make this myself with a dodgy leadscrew.This is going to be fun.

.

The problem is, Paul ... My link is to information about ACME thread-form, and yours is to the Metric Trapezoidal thread-form.

But we still don't know which form Myford actually used on the ML10

Can you make a couple of templates, to 29deg and 30deg, and photograph them against the unworn portion of your thread ?

<pretty please>

MichaelG.

I wonder if i can turn up some metal rod in the lathe , one at 29 deg and one at 30deg, take off the points at the correct depth and try them in the thread, now theres an idea.

ive got the lathe in bits, ill rebuild it and get busy on it 

Edited By Paul Smith 37 on 15/03/2020 20:29:45

Well ive set the compound slide to 14 and 15 degrees,trying to get it one 14.5 deg was nye on impossible with my eyes, thus 28 and 30deg and i think the 30 deg one fits better, thus pointing to an acme thread. I was difficult becuase even though i cleaned the leadscrew with brake cleaner, the fluid kept jumping across the gap,The 30mm pencil was solid in the thread whereas the 28 was a tad wobbly

I spoke to halifax rack n screw today, and he said its defineately an acme thread too, and hes compiling a quote for a plain threaded bar i can finish.If the quote is reasonable does anybody else want one for a group buy?

thanks Pauly.

TR16x3 threaded rod

available here in 1 metre lengths. Need to contact them for prices.

If Hx R+S are too pricy, you could try Kenward Precision & Gear in Huddersfield (01484 512355) - they have (or had when I last visited) a Jowett thread whirler, so should be able to make a lead screw.

Nigel B.

Edited By mgnbuk on 16/03/2020 16:12:31