Myford MF74A

[fastdaveParticipant @fastdave]

Hi folks, strange one here – has anyone heard of a Myford MF74A? I would like to buy this machine, but I need something which will cut 3.5 pitch (mm).

I am reluctant to swap out for anything else, but I know what Myford means – I believe this is a 1940 model, but I am willing to do any refurb necessary.

Any help on spec and model ?

Dave.

[fastdaveParticipant @fastdave]

Lathe specification

[duncan webster 1Participant @duncanwebster1]

see **LINK**

Probably Imperial, so you need to be sure there are enough changewheels to set up to screwcut 3.5mm pitch

[fastdaveParticipant @fastdave]

Thanks Duncan, that was a great link – still not terribly sure if I'm in the right ballpark with my screwcutting – but the 64 million dollar question – am I doing the right thing, or should I go in a different direction for purchase?

Dave.

[Brian WoodParticipant @brianwood45127]

Dave,

What do you have at the moment?

There are other possibilities, for example an ML7 with gearbox will cut 3.5 mm pitch threads with a 33 tooth gear in place of the standard 24 tooth driver, when matched with the gearbox set for 10 tpi

I think you may have a hard time finding the model you are seeking. 

Regards Brian

Edited By Brian Wood on 02/06/2020 17:44:46

Edited By Brian Wood on 02/06/2020 17:45:10

[SillyOldDufferModerator @sillyoldduffer]

Do you know what change gears it has?

For what it's worth 8 tpi and 3.5pitch are the coarsest threads available on my Warco WM280.

Provide it's in good condition, the machine looks a sturdy beast, but it's probably Imperial only. Might be possible to find gears and other spares for it but more likely an adapt and make problem.

Some misplaced guesswork on the usually excellent lathes.co.uk about the machine being a joint commercial venture between Jones & Shipman and Myford. More likely it springs from wartime rationalisation of British industry when government intervened to raise production by forcing firms to concentrate on what they were good at. Myford specialised in small general purpose lathes. I think this is a Jones & Shipman design, outsourced to Myford, not a real Myford at all. Nothing wrong with that. Judging by the look of the lathe, it's a pre-war design likely dropped in 1944 because plenty of more modern machines were available by then. Many American machine tools, including automatics, were imported during WW2.

Give it a careful inspection before buying. Lathes made in the UK during WW2 are likely to have been worked hard, maybe thrashed. Shift work and several different operators racing to meet production targets regardless of the lathe. Or it might have ended up in a backwater and still be in excellent condition.

Dave

[HopperParticipant @hopper]

According to lathes.co.uk it has the usual 8 tpi leadscrew. So to cut a 3.5mm pitch thread it can be done with the standard change gear set that would have come with the lathe. Specifically:

45– any idler — 35/60 — 70

According to Martin Cleeve in "Screwcutting in the Lathe" (Workshop Practice Series.) this gearing will give an accuracy of 1 thou in 3.43 inches, which is probably better than the original leadscrew when new.

So you wouild need to make sure all those gears are still with the lathe or be prepared to pay the price on eBay to get replacements — if they are the same as other Myford gears, which they appear to be.

Apart from which there are all the usual caveats with buying ancient machinery.  Sorting it out can turn into a fulltime hobby of its own long after you have forgotten what it was you wanted a 3.5mm thread for in the first place!

From a collector's point of view, it's an interesting and uncommon model. There are quite a few details on it that would appear to have perhaps been the inspiration for similar on the subsequent ML7.

Edited By Hopper on 03/06/2020 07:57:41

Edited By Hopper on 03/06/2020 07:58:18

[Ady1Participant @ady1]

I recall seeing one a few years ago on ebay and it really was quite a beautiful machine to look at, really solid

But they are rare beasts and most were worked to death in WW2

Perhaps a different similar more easily sourced machine would be easier, like a south bend

Deffo an interesting project, I dabbled with buying it but it looked like a seriously heavy bit of kit

GL

[Brian WoodParticipant @brianwood45127]

There is an even easier and simpler set up

55 Driver——50 driven on leadscrew with suitable idlers as necessary This gives a pitch of 3.493 mm

Regards Brian

Edit PS  This would work with any lathe having an 8 tpi leadscrew

Edited By Brian Wood on 03/06/2020 10:36:30

[HopperParticipant @hopper]

Lol you should write a book on this stuff, Brian! Occams Razor of course goes for the 55——-50 in spite of the much "larger" variance,, which of course is still plenty accurate enough for home shop work in most any imaginable instances.

Edited By Hopper on 03/06/2020 11:16:05

[Brian WoodParticipant @brianwood45127]

Maybe I should Hopper!

I just like dabbling with such calculations and sometimes a delightfully simple arrangement emerges, which in this case is plenty accurate enough for most purposes.

Brian

[Jon CameronParticipant @joncameron26580]

If i'm right the change gears from the ML7 are compatible with the 74. So even if it doesn't have the needed gears you should still be able to buy the missing gears for the lathe.

Though as Brian points out there is usually one option using a selection of gears to hand, it all depends on the accuracy of the thread needed, which again depends usually on the length of thread. Brian That screw cutting book would be handy in a lot of applications. Just a shame my brain is a bit weak in gear ratio calculations and such haha.

Regards

Jon

[Brian WoodParticipant @brianwood45127]

Jon,

Do I detect a demand for it? If so "Hey Presto", it is already published and waiting, how's that for anticipation!!

Regards Brian

[fastdaveParticipant @fastdave]

What an incredibly helpful bunch of guys, with a remarkable fund of knowledge.

I discovered, on re – entering the mechanical engineer's world, after having a tangential apprenticeship to electronics, and later Heavy Electrics, that mechanical engineers are invariably more knowledgeable and eloquent (generally – I know this will get a lot of hackles raised).

I think this is because it is very difficult to fasten things down to micro anything in electronics, and the tolerance is even wider in HV, whereas one can touch and see everything mechanical. Maybe this is why the guys I was teaching to be multi tasked always went easy from electrical to mechanical – but the engineers never trusted electricity (again, generally)

Go on -crucify me, but try reading 17th edition electrics, then 16th, then 18th, then read an article from MEW.

I rest my case for the offense.

Dave.

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