Myford ML4 Restoration: Headstock bearings and spindle removal

Hello again Luke,

Part 2 got lost so I will have to do it again from memory, most annoying.

This stage describes the steps to rebuild the headstock

Draw the bearing shells into the housings with a long bolt and wide flat washers either end to pull them in square. Don't draw the front bearing into the thrust bearing pocket. Make sure you have the oil holes on the correct side and that the split aligns with the gap in the housing

Assemble the spindle and the thrust washer on their own into the bearings shells to see how the spindle feels in position when the bearings are slack. Oil the bearings and tighten first the rear, then the front and finally the thrust bearing [ Make sure there is a soft washer under the grub screw to avoid bruising the thread] Test the feel again, there should be detectable drag by hand on the spindle nose thread.

If this feels OK pull the spindle out again and rebuild with the cone pulley and an intact bull wheel. You might have to increase the dimple depth for both grub screws, the one for bull wheel looked pretty well chewed up. Don't forget to fit the belt!

Refit the 25 T gear. I think it had been fitted much too far on previously, just sufficient for full engagement with the reversing gears below it is correct. The gear will tap on with a soft faced mallet and test it is going on square. Also make sure the two halves of the 2 BA screw hole are aligned. Test with a screw for thread engagement without binding , then run a 2 BA tap in to refresh the thread. Cut somewhat deeper this time, blow out the swarf and fit a grub screw; Finish with thread lock

Now set up the bearings again to just get drag on the spindle and run the lathe for 1/2 hour or so on a slack belt to bed things in. Feel the bearings as this test proceeds, they should not get warm. If all OK then tension the belt and run for a further hour, listening and feeling bearings during this time for signs of distress. Oil the bearings frequently as well.

That will be sufficient I think for a usable machine. It will NOT be up to Dean Smith and Grace tool room standards of course, these machines sold fully equipped for £50 or so in their day

A new thrust bearing if you need it can be bought from either of the following suppliers;

Bearing Boys or Just Bearings. They both have websites

I hope that helps and gives you some reassurance.

Kind regards Brian.

Edited By Brian Wood on 01/05/2020 12:09:40

Looks to be in quite good condition. And fitted with tumbler reverse, (not all were )

So will be 3.5 centre height. The Mandrel thread started out at 7/8 BSW, (9 tpi )but changed to 7/8 x 12 tpi.

Possibly, so of the last ones produced may have even had what we now think of as Myford standard 1.125 x 12 tpi thread.

The Cross Slide Handwheel looks to be a shop made addition, possibly to overcome the odd increments of the original 80 division dial on a 12 tpi screw, giving a 0.00104" increment.

If you have a complete set of changewheels an additional 20T and 60T would allow you to set up for a fine feed of just over 0.004"/rev. For this, you may need to fettle the Mandrel end of the slot in the Banjo. The train is

20 : 60/20 : 65/20 ; 60 on the Leadscrew.

Brian will be far more able than I to state the trains for screwcutting various threads.

A quite useable machine. Possibly, someone came up with a modification to change the saddle traverse to that taken as normal, instead of the ex factory seemingly reverse action. (but it was made down to a price, when manufacturing was difficult, nearly 80 years ago )

Enjoy yourself with it!

HTH

Howard

Edited By Howard Lewis on 01/05/2020 16:02:16

Hello Howard,

Thank you for the compliment, I hope I can live up to it.

Luke said at the start of this thread that the mandrel nose thread was 3.125 inch x 12 tpi, as well as giving the other parameters that were common to late issue ML4 lathes it is the same model that my Dad bought new in 1945 and I was allowed to use as a 7 year old.

That nose thread would be ripe to accept a simple collar modification to allow ML7 spindle fitting hardware to be used, I don't know what other chucks he has inherited.

Thus far we know nothing about the state of the Morse tapers. I am hopeful that they have survived unscathed after all these years. We also know very little about the state of the bed. It is very likely to be worn at the chuck end, but that of course doesn't mean the lathe cannot be used---it just needs due allowances for age

Like you, I thought this could be restored to a fair working machine, Luke seems to be capable and with the family history of ownership from Grandfather---Father---Son it seems only fitting to get it fully operational again.

Regards Brian.

Edited By Brian Wood on 01/05/2020 16:50:27

Hi both,

I've included an image showing the ways (I posted it originally but I no longer trust Google and so I've re-uploaded it, elsewhere). They are indeed a little worn near the chuck, and a little discoloured at the far end beyond where the tailstock usually sits, but they still appear to be flat and mostly true. There is a slightly tight spot in the middle of the bed that it can be a little difficult to get the tailstock past but it's nothing to complain about.

If I can get the rest of the lathe running reasonably true then I will investigate regrinding the ways and re-seating the saddle. If possible (and particularly due to the history of the lathe, as you say Brian), I would like to restore it working order in the best way possible. I'd need to contact a local machine shop and get some quotations for this work but I fear it will be rather expensive.

The tapers seem to be in good condition. The headstock is bored to MT2 whilst the tailstock accepts MT1 tooling. I haven't noticed any wear to either and the tooling I've used fits snugly - indeed it becomes quite difficult to eject from the tailstock and needs to be knocked out with a wooden dowel and a mallet. Many other lathes, I notice, are abke to auto-eject tooling. Perhaps that was a later development.

I've used the tailstock taper quite a bit to support work (a necessity given the play in the headstock and, I suspect, a slightly worn 3-jaw). I've also used it for drilling and reaming and it performs well at both tasks.

It did take me some time to get the tailstock properly aligned to the headstock and the first few holes I drilled we a little off-center. Once I'd managed to slackened off the bolt holding the castings together I could use the set-over adjustment, a knurled wheel on the rear, to center the points of a taper held in both tailstock and headstock. The tailstock is still a touch lower than the headstock and I will have to use some shim stock to raise the casting. I'd also like to purchase a test bar to make sure my adjustments are accurate. (But all of this after the headstock bearings are in order).

Workholding-wise: I have a 3-jaw self-centering chuck ("British Crown", fitted in the photographs), a 4-jaw independent chuck ("British Crown" and a spare 3-jaw that I need to restore. As I mentioned, the 3-jaw doesn't hold stock very true and I suspect the jaws are worn unevenly. Any information about this would be appreciated but, if I can get everything else tightened up, I will look into grinding them concentric in-situ using a toolpost grinder (which I'll have to buy/make/cobble).

I have the original toolpost, which is a simple vee-shaped piece of steel with some patterning for grip, but I believe it's missing a spring and a secondary bolt. It's on my list to make up these missing pieces so the original toolpost can be used again.

I've installed an Indian-made Dickson-style QCTP as I quite quickly got fed up of shimming up tools to the center height. It's not the best quality but it works well, especially after I made up a brass bushing to grip the supporting bolt a little tighter. On this note, as I think I mentioned, somebody has previously re-threaded the tool post bolt on the top-slide for M10. I don't know if the original thread had worn or whether there was another reason.

Brian, when you say this, do you mean the spindle wont accept ML7 hardware as it is? I was under the impression that, given the thread form and dimensions, ML7 backplates etc. would fit. May I ask what the difference is?

Hi Howard,

Thanks for your comments.

I have most, although not all of the changewheels. I'm missing 2x20T, 45T, 70T and 75T from the original set, although I may buy a spare 25T too as the one I have is cracked and I fear it may break at some point. I will try and braze it once the lockdown lifts and I can use a friend's set-up. I've also got a 28T, a 38T, a spare 35T and a spare 50T.

For record, I've been told the original set is: 20, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75

It does, I too have wondered at the reason. I'll count the increments and see if I can come to any conclusions. I'd assumed, initially, that it may have been made to replace a missing or broken wheel as the original is no where to be found.

Kind regards,

Luke

Hello Luke,

Just briefly if I may.

The spindle nose configuration of the ML7 has the same thread as your lathe, but the plain chuck register is 1.25 inches in diameter. The modification is to make a close fitting sleeve to bond to the 1.125 inch diameter register you have and then machine the o/d using the lathe itself to finish the OD to ML7 size

You would of course need to open the register diameter on your current range of chucks.

Kind regards Brian

Edited By Brian Wood on 01/05/2020 19:21:01

Hi Luke,

The more I read, the happier I am for you!

Shall probably get chastised by the ML7 followers for this heresy. Helping someone recommission a ML4 with 7/8 BSW nose, I cut a couple of 20T gears, and added a 60T left over from my ML7. All had to have a hole drilled part way through to accept the 3/32 driving pins. If you do this, drill the hole away from the keyway!

Not sure if 70 and 75T were part of the original changewheel set up. Thought that it stopped at 65, ,but I could be wrong. Will the Lathes UK site confirm / deny?

If you graduated the Handwheel with 83 divisions, that would be nearer to 0.001"/ division, but not absolutely accurate, (0.0010040161" per division to be pedantic )

I like Brian's suggestion of bonding a sleeve onto the Mandrel to bring the register up to inch and quarter

Might be a bit of a chicken and egg job to modify the chucks.

My suggestion would be to mount the 4 jaw and clamp the 3 Jaw to a piece of bar. Adjust the 4 Jaw until the register of the 3 is running absolutely true, before opening it up to inch and a quarter. Still using the 4 Jaw, hold a piece of bar, larger than inch and a quarter, and turn the OD to snug fit in the register of the 3 Jaw. Then bore the bar to the diameter of the original register on the mandrel (which you will have measured as accurately as possible before starting this! )

Part of the sleeve to length, and deburr.

If it is a tight fit on the Mandrel, you may be able to heat it, to produce a shrink fit.

Having fitted the sleeve to the Mandrel, mount the 3 Jaw (hopefully a really snug fit ) and skim a bar to produce a true concentric diameter.

Clamp the 4 Jaw to the bar, register outwards, and adjust its jaws until the register runs true.

Bore out to the OD of the sleeve, or a thou oversize.

Hopefully, you should then have a Mandrel and two chucks that are compatible with other Myford 7 Series fitting items.

If you have a Faceplate, or anything else fitting the original register, you will need to treat that in a similar way to the chucks..

HTH

Howard

..

Hi Howard,

it does indeed seem that 70 and 75T are non-standard and were available to "extend the threading range" (see lathes.co.uk).

There was recently a set of ML1/2/3/4 changegears up for sale on eBay that I contemplated but the lot sold very, very quickly. I think I'll buy the gears missing from my set from the available ML7 stock and drill the 3/32 holes for the pin (opposite the keyway). It seems easier than waiting for [rare] earlier gears to crop up.

There is also a fixed steady available on eBay at the moment but only for the earlier 3-1/8" center height. I'd love the opportunity to acquire an original fixed steady for this ML4 but I may have to do with machining down one for the ML7. I believe the ML7 travelling steady will fit with minimal modification, however.

Cheers

Edited By Luke Mitchell on 01/05/2020 23:13:00

Hello Howard and Luke,

I was quite taken up with Howard's suggestion for re-machining the backplate register on Luke's chucks. I do however see a snag which would ruin the whole operation.

It depends crucially on the quality of grip of, say, the three jaw chuck on the machined spigot held in the four jaw chuck. Luke has already said his Crown 3J chuck has a lot of wear and uncertainty of grip in the jaws which means it will grip the spigot well enough but would that be without a wobble at the register position?

I think instead there is little alternative to removing the backplate from the chuck to be modified so that the register position can be set correctly in both planes.

When I carried out the modification on Dad's lathe I had the advantage of owning a second 4 jaw chuck, big enough to grip backplates on their own so that location in the two directions could be assured.

Good news for Luke

You will find that the location tongue of a fixed steady for the ML7 will also fit the central channel between the ways on your ML4. The gap width is 35 mm. Whether the position across the bed of both lathe designs is sufficiently close as to be insignificant I don't know.

I made a large 4 arm steady for the ML4 to machine the bearing pockets in the quill tube on my Dore Westbury milling machine and have used that on my ML7R many times without being aware of cross bed misalignment

Kind regards Brian

Hello again Luke,

I have just been reading back over the recent correspondence and noted your report on the cracked 25 tooth gear.

I feel sure I am correct; Myford made the smaller gear sizes in steel, which would include 25T. The other sizes upwards were made in cast iron

My question is how on earth did a 25T gear in ductile material get cracked? I can only think that there was at some stage in it's life one almighty lock up, maybe from running the tool into the chuck or something on those lines for there to have been sufficient strain induced in the gear to crack it. If that happened on this lathe I would look carefully at the other elements downstream of the change gears for evidence of damage.

It may of course have been bought in along with other things, in which case you will see nothing untoward.

I recently rebuilt the screwcutting gearbox on a 1902 US made Hendey lathe fitted with an original Norton box. That had been very badly beaten up in a hard life and I had to make a completely new set of gears for it but the point of the story in that while the cast iron [Yes--cast iron!] gears were mostly devoid of teeth, the smaller steel ones still had teeth, all bent and distorted. , some worn down to stumps, but NONE were cracked.

A cast gear would have fractured---I remain puzzled

Clamp it together when you braze it to prevent it opening like a flower and anneal it well afterwards to relieve strain

Kind regards Brian

Quite right Brian,

I had forgotten that the 3 jaw was questionable about grip.

Could this be overcome by using bit to produce a"collet" to hold the bit of bar? A relatively thin wall would allow it to collapse and grip the bar, hopefully retaining the alignment and grip of the dicky chuck.

(A candidate for a bit of in situ jaw grinding with a Dremel? )

As you say, tit may be possible to use the 4 jaw to turn the backplate register of the 3 jaw. If the backplate / chuck fit is tight, concentricity errors should be minimal.

Howard

Hello Howard,

I am inclined to think that introducing another variable, in this case a thin walled sleeve, will only add to the problems of concentricity. I really can't see much alternative to removing the variables and machining the new register while it is held soundly in the 4 jaw chuck.

Kind regards Brian

Hi Brian!

Correct again!

The fewer variables, the greater the rigidity and accuracy. The "collet" would be a bit of a last resort., in my mind.

The risk here, is that dodgy 3 jaw chuck. if a means of improving its grip and accuracy can be found, things will improve. I wonder if the problem stems from wear between the scroll and the jaws, or jaws and chuck body.

Even grinding the jaws, in situ, will probably only mean accuracy at that one diameter with discrepancies elsewhere.

Anything that can be done to reduce the play has to make things better.

Maybe, the ultimate solution is to scrap it and buy a new one, with a "Myford" register, funds permitting?

Howard

I hope Luke doesn't mind me butting into his thread but I have also recently acquired what i believe to be an old ML4 lathe with a view to fettling it back to usable condition and hopefully learning how to use it. Reading this thread and a couple of other related threads on this forum having found them by googling info on the ML4, i have found the information most useful.

My lathe, to my inexpert eye at least, doesn't look to have excessive wear in it,i think it was used for many years by a model engineer and hobbyist, in more recent times it's been owned by a guy who wasn't really an engineer and was just playing about with it occasionally, so it's neglected a bit but i think basically ok. In all i was quite please with the purchase which was a blind buy on ebay, until that was i took the guard off the bull gear, you can probably guess the next bit.

I've realised that the drawback with these machines is the lack of spare parts, i did manage to purchase an incomplete similar lathe with just the major components on it, head stock, cross slide and tailstock, with a good bull gear on it, for £60 on ebay just before the problems with the covid virus became apparent, however it's quite a way from where i live and i've got no way of getting it back here whist the lockdown is in place.

I'm planning to convert the spindle to take an ML7 backplate as suggested here by Brian Wood, so the information on this thread has been extremely helpful to me

many thanks

andrew

Hi both,

Many thanks for the musings about my 3J chuck and the register adaption. I will need to think about it and weigh up the pros and cons of the process - it certainly seems worthwhile, on the face of it, but perhaps not urgent unless I fail to true up my chuck (in which case I suspect I will have to buy a newer one).

Since removing the spindle I have cleaned up the spindle gear and I’ve left the thrust bearing in some acetone to degrease it. It looks as though there are a few flats on the ball bearings and so I will be replacing it. I’ll take some measurements later today and find the appropriate part. I’ve also deburred the spindle using a fine file and a stone so hopefully I will not damage the bearings when I refit them - it was a nerve wracking experience but I think a successful one. We shall see.

I will take a look at the 25T gear too and take a photograph. I’ve not noticed anything that would indicate a crash - the change gears all seem to work and fit well and the lead screw is in good condition (although there is a bit of a flex in it, I’d chalked that up to the thickness/length). Perhaps the crack is nothing more than a scratch that is full of old swarfy oil.

More updates soon.

Kind regards, Luke

Hello again.

I dug the thrust bearing out of the acetone - it's partially cleaned up the muck inside it but it will need a bit longer, and possibly some agitation. Here are a couple of photographs in which you can just see the flat spots. The flats on the ball bearing at 8 o'clock and 4 o'clock in the second photo are particularly obvious.

As for the 25T gear, it was indeed cracked. It's strange as the teeth of the gear look in very good condition. It looks as though my changegear set has been taken from an ML7 as each gear has a keyway cut into it. See the photograph below.

Kind regards,

Luke

Here are another photo of the cracked gear (I posted my previous message in a hurry as I was late for an online chat with a friend). I couldn't discern any noticeable difference in material between the 25T gear and the larger sizes - as you can see in the second photo they all look very similar (and are in remarkably good condition, to my eye).

Hello Luke,

The thrust bearing

I suspect the bearing has been skidding. You did say some while back that the screwed collar was slack so there would have been no pre-load on it. It was also lubricated with grease which would tend to hold the balls in position as the grease dried out and it got stiff, adding further to the problem. Buy a new one, it should be realistically priced

The cracked gear

I was right it seems, this was NOT original supply, Keyways were introduced in ML7 change wheels, not for the ML4. Starting from the stress raiser in the keyway corner it must still have been given a substantial shock to have cracked. However, it will salvage well. I suggest you drill out down the centre of the crack at the tip to remove the stress raiser there in particular so that you can get braze metal all the way through onto clean metal and anneal it by very slow cooling after the brazing with it buried in vermiculite

Kind regards Brian

Hi Andrew. Forgive me for ignoring you, I must have missed your comment earlier.

I agree that one of the more difficult aspects of owning an early Myford is the lack of parts that are available. Looking on eBay there is a wealth of spares and accessories for ML7s, ML10s and the Super 7 lathes. The lack of detailed information is also a problem as, until finding this forum, I’ve had to piece everything together myself. I did buy the data pack from lathes.co.uk but there wasn’t a great deal more than can be read for free - just some nice figures and old sales photographs.

Brian mentioned earlier in this thread that he had a spare 60T bull gear. You might consider asking him to purchase it to replace your [rather unhappy-looking] one. I can’t tell in the photo but are your back gears in decent condition? There is a backgear cluster for sale on eBay with only a single missing tooth that may also be of interest to you.

Kind regards

Morning all,

I've just taken some more measurements for the thrust bearing assembly and I'm looking for a replacement to purchase.

The measurements I took were as follows:

OD: 41.3mm (1.6" )

ID: 25.73mm (~1" )

Depth: 11mm (7/16" )

Taking a look at some of the bearing providers it seems that this is close to a standard size that's still available: 42 x 25 x 11mm.

My next question is that both ball bearings and roller bearings are sold. It is my understanding that roller bearings are superior and I was wondering if it would be worth considering "upgrading" the existing bearings for a roller-type bearing?

See ball-type and roller-type bearings.

Kind regards,

Luke

Edited By Luke Mitchell on 04/05/2020 09:31:17