The actual serial number may be at the right hand end of the bed. 366 is the assembly number for keeping track of matching parts in a batch.

I recommend clear Waxoyl (car underbody wax) diluted a little with white spirit for everything other than bearings and sliding surfaces. It is much nicer to handle than oily things and dries to a tacky surface like post-it glue. Then use beeswax purniture polish (NOT silicone) for handles you touch in use.

I derust with phosphoric acid, as available by the gallon for swimming pools, painted on for a few minutes not soaked, then washed off. This leaves a slight phosphate coating depending on the material.

Hello Hugo, and welcome to the forum.  The  ML4 is a good little lathe. I have owned three over the years, and used them professionally.

First, to work out which model you have, I’ll quote myself from an earlier post:

“To quote a post I made in an earlier thread, quoting a post I had made in an even earlier thread:

” “Some simple measurements and observations can identify which of the different models ML1 to ML4 one is faced with:

ML1 & 2: 3 1/8″ centre height, 15″ between centres, 3 1/2″ cross slide travel.

ML3 & 4: 3 1/2″ centre height, 24″ between centres, 4 1/2″ cross slide travel.

ML1 & 3 (‘Standard’ models): Spindle bearings direct in headstock.

ML2 & 4 (‘Superior’ models): Bronze spindle bearings, shrouded ball thrust race.

My understanding from lathes.co.uk is that the cast-in headstock was abandoned in 1937, so from then until the ML1 and ML3 went out of production in 1941, all models had the removable headstock.”

The ML4 used three different spindle nose threads, Earlier ones 7/8″ x 9tpi or 7/8″ x 12 tpi. Later ones used 1 1/8″ x 12 tpi, the same as the ML7 but with a smaller register diameter. I don’t know what threads were used on the ML 1,2 &3 but they would almost certainly have been the same.”

Since your lathe has a serial number, I would guess it’s one of the later ones, and the most likely model is the ML4 simply because they were made in larger numbers.

All my information has come from Myford documents or from lathes.co.uk. 

Incidentally, if you do searches on this forum for “Myford ML1” through to “Myford ML4″ you will discover that there is a wealth of valuable information and experience concerning that family of lathes.”

How many divisions are there on the micrometer dial on the cross-slide? If there are 100, don’t believe it.  The ML1-4 were made with a 12 tpi feedscrew, which means that one turn of the handle advances the cross-slide by 83.3 thousandths of an inch. I suppose the designer thought it was a good idea…

You should find that the small threads are 2BA, and the bigger ones are BSF, mostly 1/4″ and 5/16″. Your toolpost is not a Myford original.

My first ML4 had the earlier 7/8″ thread and a 4″ chuck. The overhang and small spindle gave very poor stiffness, so think long and hard before trying to fit a bigger chuck! Judging from its appearance, yours is likely to be the later ML4 with the 1 1/8″ spindle nose thread, so stiffness should be less of an issue.

George

On 28 April 2026 at 00:03 Nigel Graham 2 Said:

 

Regarding George’s point about the 12tpi cross-slide feedscrew. That is a strange pitch! My Denbigh horizontal mill has two 6tpi screws so gives the same puzzle.

 

Perhaps not really strange.  I don’t think these pre-war machines were originally designed to have micrometer dials.  Machinists worked differently then.  The pitch of the screws was probably chosen to give the right feel in operation.  The only measuring tools available to the user were a pair of callipers (spring bow if you were fancy) and a rule marked in 1/64 of an inch.

Rod

This thread brings back some memories of 1968 or so and me with my first lathe courtesy of Dad!.  Even the motor is the same but I had to construct a countershaft assembly as it was distinctly missing.

I believe that you have the ML4.  The cross slide thread is indeed 12 TPI but the handwheel dial is a later fitment.  Mine were brass discs engraved with 80 divisions.  It took me well over a year to find out why parts were forever coming out undersize but of course 80 divisions and a feed of 83.33 thou per turn makes for problems.

I did make a 12.5 tpi screw and tap (under Grandad’s guidance) and tapped out a bronze bush which was grafted into the cast iron saddle with loctite and a cross pin to one side.  If I was doing the job again, I would make the thread 20 tpi for imperial or 1mm pitch for metric and use a standard whitworth form tap & die to make the parts (you ain’t never going to wear them out).  I can’t remember the thread OD but it would have been 5/16 or 3/8.  That way you can keep the 100 division dial in 1/2 thou increments travel or 1 thou off diameter.  I remade the dials but ultimately a true 80 thou/rev is still a short cut to errors in mental arithmetic and scrapped work.  I suspect the top slide has the same problem but tends not to be so annoying.

Good luck, they are a nice little machine but don’t expect to be parting off 2″ EN16 with it.  I built a Rob Roy loco with mine (eventually).

Martin

That’s a fairly horrible weld repair next to the leadscrew clasp nuts on the apron.  It might have distorted the slides for the clasp nuts, so maybe check their fit and function.

If the weld is holding, leave it be.

Martin