Yes. Each turn of the handwheel and leadscrew is 1/8" or .125" so you are correct.

My M-type has had the outer diamter of the leascrew handwheel turned flat and the graduations and numbers etched on there. Works very well and very simple. Can be done on the lathe itself by using a plunger engaging with the change gears to index the chuck while holding the handwheel in it. Graduations are put on with a toolbit turned sideways and racking the carriage back and forth. A carriage stop can help get graduations correct length.

I don't know about Myford building errors into cross slide feedscrews etc. Could it possibly be wear after all this time?

Edited By Hopper on 10/06/2020 09:27:30

Hopper,

Just to to avoid the suggestion that the 'errors' are deliberate, the feedscrews for cross and top slide on these early Myford lathes were made as 12 tpi square form, the dials were given 80 divisions so tool movement was an approximation. Myford say in their handbook that it is probably 'good enough for most purposes'

Regards Brian

Edit I see that Jon got there first with the 12 tpi screws.

Edited By Brian Wood on 10/06/2020 10:16:56

Just to prove the point, 40 T on the mandrel and 50 on the leadscrew with idler(s) as necessary to link them will cut 10 tpi on any lathe with an 8 tpi leadscrew

Brian

I knew that Myfords took over manufacturing the Drummond 'M' type at the start of WW2 because, to quote lathes.co.uk "their contemporary models, the ML1, 2, 3 and 4, were completely unsuitable for professional work"

Could this be because of the inaccuracies in the slide leadscrews?

I'll let you into the secret Hopper, I use my calculator too!

Regards Brian

Edited By Brian Wood on 10/06/2020 13:49:53

Who would want them, and what for?

Although they're maybe at the upper end in terms of quality, early Myfords are typical of any number of the basic pre-war machines sold to amateurs. Small, lightly built, simplistic, and relatively weak. Yes they do good work in skilled hands, but they're not robust and fast enough for production, or suitable for high-precision, or capable in the way valued for prototyping or laboratory work, or good for training servicemen and apprentices. Considerably inferior to Myford's post-war lathes, which killed the range stone dead, and to the contemporary and far more expensive Drummond M.

I don't think anyone with production targets and tolerances to meet would want a pre-war Myford. For similar reasons, despite their many virtues, ML7 and Super 7's weren't popular in industry or education either. They prefer robust precision to delicate precision, and are prepared to pay big money for it.

You don't see industry snapping up Chinese Hobby machines either!

Dave

Rod & Dave –

The Drummond/Myford M Type, again according to Lathes.co.uk, "had been adopted some years before as the standard model for the Armed Services."

The powered cross slide was only fitted to admiralty versions of the M type so most of these were not that different to the ML1/2/3/4 in specification, but were preferred for some other reason.

Your points regarding the general capability of the lathe I acknowledge, as has been done elsewhere, but as far as I can tell most of these apply equally to the M Type as well as the ML series..

Edited By Nick Clarke 3 on 10/06/2020 17:16:11

Edited By Nick Clarke 3 on 10/06/2020 17:16:50

.

Just a thought …

The approximation is reasonably expedient for those working to decimal drawings

… Not dissimilar to the situation we currently see with some ‘Metric’ lathes.

So the underlying question might be:

When those early Myford lathes were first made, was anyone using twelfths of an inch ?

MichaelG.

.

[*] remember that twelfths survived for a long time on school rulers, and that both ‘twelfth scale’ and 1:144 remain common.

Twelfths:

Is there an indirect link with pounds, shillings and pence?

Twelve is a useful number for dividing purposes.