Myford ML4 cross slide

Refurbishing my ML4 lathe and everything is acceptable apart from the amount of play between the cross slide threaded bar and the tapped hole in the carriage that slides of the bed plate. Can upload a photo later. It has a buttress thread form and is 5/16" in diameter and 6" long.

Has anyone got a NOS of these or am I making a new one from scratch?

..pretty sure that the feedscrew is Acme form, mine is 5/16 x 12tpi.

There might be a couple of unworn turns right next to the handle end where you'll be able to see the original profile.

I suspect the chances of anyone having a new one are very slim indeed.

What is a  ....EDIT...........NOS? You,ve got fingers and a keyboard, spell it out, and use the language. Lynne

Edit Preferably not Foul language

Edited By JasonB on 14/05/2022 18:47:20

Ha ha, I don’t suppose you know what OEM stands for, either. Most people know these common acronyms.

But nevertheless, no need to post expletives to get your point across. Gives the impression of drink related from my POV. Sometimes, less language is better?

To the OP.

Doubt it is too difficult to make a new feed screw from scratch, but an alternative would perhaps be to source (or turn) a piece of the screw thread and join it to the rest of the current feed screw parts, after removing the old threaded section and carefully preparing the ends so they can mate together and be fixed in that position.

Regarding the female thread - can that be bored and bushed? Suitable taps are (relatively) easily available, for cutting the thread.  Another possibility might be to use the next size up for the threaded parts, if appropriate.

Failing on those options, I would expect the current threaded hole could be filled in and reworked.

Edited By not done it yet on 14/05/2022 07:10:51

NOS - New Old Stock.

It did take me a little while to work it out.

Alan.

NOS - New Old Stock - ubiquitous in classic car and bike worlds

Well, I don't think anyone reading the thread this morning will be thinking that it's the OP's posting that is of little credit to him, will they..?

Anyhoo - how bad is the wear?; I ask because although the screw helix in mine is visibly 'thin', after careful adjustment of freeplay at the handle end, the backlash comes down to about an eigth of a turn, which is pretty respectable for an old assembly and certainly useable for turning and facing, even if parting off could be a bit exciting..

If you can give us a bit more detail, post a pic or two it might be useful - I'll try and post a picture and some measurements for comparison later this morning..

Edited By DiogenesII on 14/05/2022 09:31:46

My first lathe was an ML4 and the cross slide screw is indeed 12 tpi, which whith dials calibrated to 80 divisions is a recipe for making parts consistently undersize. Go do the maths, but don't ask me how I know! Anyway, I still have the tap I made to cut a bronze nut whichh was loctited and grub screwed into the saddle.

Having said that, if I was doing it all again I would use 20 tpi which I think could be 3/8 BSF (or isit 5/16?), then remake some decent size dials.

If you want the 12 tpi tap, PM me.

Martin

Backlash in itself is not harmful, and it should be routine practice always to make settings and apply feed from the same direction to eliminate it.

If the cross-slide feedscrew is only worn on some threads the feed-per-turn will vary slightly from turn to turn, so you won't get exactly 83⅓ thou for each turn. How often and how much would that matter?

Father compromised on his ML4 by putting packing between the cross-slide screw-plate and the cross-slide casting, to bring forward the less used portion of the thread. In all the years I used it I never noticed the difference, and for some years I used it to produce commercial parts.

George

Is it possible to open up the original threaded hole and fit a top hat bush with two screws (a la ML7) and fit it with 2 ba screws.