Myford VMC Spindle Advice Please.

[Nigel Graham 2Participant @nigelgraham2]

I bought the mill second-hand some years ago now, lost the drawbar but succeeded in making a self-ejecting replacement. I use it frequently, even treated it to a Machine-DRO 3-axis set; but am plagued by two difficulties.

1) Stiff quill action, too much for the return-spring to act, making sensitive down-feeding for drilling a bit of a gamble.

2) Problems inserting, and sometimes removing, tooling. The spindle uses an R8 taper and I have the impression that it contains a key that has worked loose.

 

Studying the machine and the manual, which shows a sectional drawing but no instructions, suggests the quill pinion is accessible through the back of the casting, necessitating removing it from the ram. This may allow freeing the stiff quill, if the cause is simply hardened grease.

However, further work especially to solve Problem 2), may entail complete dismantling.

 

Has anyone performed such operations on one of these milling-machines, and can give me any hints and tips, please?

I have put off repairing it so far partly because I am very wary of releasing the quill spring. I don’t have the tools or expertise to manipulate these difficult, potentially dangerous, springs.

[BazyleParticipant @bazyle]

R8 spindles have an anti-rotation pin that engages the collet keyway. I have seen a lot of comments over the years of people removing this (typically from second hand Bridgeports) because missalignement results in a damaged tool and the pin being squashed which is then shorter, fails to stop the tool rotation resulting in gouging the tool and jamming it in place.

With regards to the spring try pretending to tighten it. That will lead you to finding a way to attach a spanner or whatever that can then be used to help let the tension down under control.

[alecsParticipant @alecs]

And wear leather workman’s gloves when playing with such springs.

[Nick HughesParticipant @nickhughes97026]

Quite often, it’s the Quill Locking parts not moving freely apart, that causes a stiff Quill.

Always worth dismantling the Quill locking assembly, cleaning, lubricating and ensuring that both half’s can slide easily and smoothly within the housing bore, before delving deeper.

[Nigel Graham 2Participant @nigelgraham2]

Thankyou.

Bazyle –

A pin rather than key (I’d imagined a rectangular block held with a screw). Trying to manipulate the collet and draw-bar suggests something loose needing wiggling with the collet, but a badly distorted pin might give the same results.

 

Alecs –

Gloves – and safety-glasses. In my teens I sometimes tried to “repair” old alarm-clocks, so I know what these springs can be like.

 

Nick –

Nohtiung ventured, nothing gained. I’ve just broken off typing this to go and look. The lock was a bit sticky but not seriously. I removed it, cleaned it and the bore in the casting, lathered it with oil and re-assembled it. It didn’t seem to make any significant difference.

One irritation with it, is that when slack the little locking-handle catches under the down-feed stop. A thin penny-washer of appropriate thickness should cure that by moving the grip point round a bit.

The key-pin problem will still need the spindle removing, somehow, but the less dismantling needed, the better.

+++++

While exploring the mill’s upper reaches I found this specimen was manufactured for Myford by the Kao Fong Machinery Co., (of Taiwan) 45 years ago this month. The type letters are prefixed “KF-“. A label on the belt-guard says it was supplied by Buck & Hickman, but I don’t know to whom. I bought it second-hand, from a motorcyle-builder, but he might not have been the first owner. At least it’s in generally good condition – no surplus holes in the table, etc., though there is a curious “spare turn” in the long feed screw at some point.

I wondered what had happened to Brammer, Buck & Hickman, which included Roebuck.  It seems to have disappeared. Not really: it’s changed its name to, or become part of, (not clear which) “Rubix”, still a British company, to “reflect its creative and human approach to problem-solving”. Which clause suggests it’s been wasting money on Branding Consultants!

+++

Now to think how to cure the spindle key fault…..

[Michael GilliganParticipant @michaelgilligan61133]

Nigel

As per Bazyle’s useful note … you might find this worth watching

… It’s gently paced, informative, and softly narrated

.

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MichaelG.

[alecsParticipant @alecs]

If you think hardened grease may be a cause of stiff quill action, maybe judicious application of WD40 might soften it up???

[Nigel Graham 2Participant @nigelgraham2]

Michael –

I have the video running but unfortunately the narration certainly is soft. Silent in fact!

My PC has given up on sounds! I have noticed this on other videos and assumed it was something to do with them; but more likely the problem’s here. The Settings appear to expect a pair of “Realtek” loudspeakers (other brands not available?) but I’ve been able to listen to videos with the internal speaker without problems, previously.

The Mute/Unmute tool has no effect but I found how to turn on the subtitles – which seem written by a SpielCzech and Grandmacorrect on spheroids.

 

Anyway, I watched it carefully, hoping for some possible leads, though I don’t know how closely the Myford mill matches the more sophisticated Acra turret version.

It seems to show the pin is basically a grub-screw with a spigot end, plus locking screw, hidden inside a recessed ring with left-hand thread and a fine but important gap between its face and that of the head. That’s likely a copy of the original Bridgeport detailing.

However it also shows the pin is only just above the taper inside the spindle (accounting for the very long slot on the tooling) so replacing it does not need taking the whole head to bits.

 

Interesting, his saying some machinists reckon the locating pin is not necessary. I am not convinced by that. If it’s there who am I to argue with the designer of both the machines and the tooling?

 

Alecs –

I’ll try that. The problem is getting the WD40 into the right area. I don’t want it washing lubricant out of the bearings. Last night I squirted oil down the splines and all over the little bit of quill and its rack that show on lowest setting, and have not yet seen if that had any effect.

[Nigel Graham 2Participant @nigelgraham2]

SEQUEL to that post.

I submitted it then traipsed down the garden to see what’s what…

I could feel what seems the remains of the locating-pin just above the taper, but that is as far as it goes. Looking up at the spindle, the lowermost bearing is flush with the end face of the quill. The quill seems to end in a thick flange that on raising, comes up against the head casting.

Back indoors, I dug out the “service manual”, such that it is.

This confirmed my suspicion that the collet locating-pin is somewhere within the depth of the two bearings in the lower end of the quill, but it is not shown on the sectional drawing, nor cited in the parts-list.

So whatever its consists of is a mystery, and finding out would entail removing the spindle and quill from the head.

The quill appears retained by its rack portion being entirely within the length of the whole unit, so cannot be removed without removing the pinion shaft and return-spring, etc.

The spindle’s top end seems to be in a splined sleeve, so might simply slide out of that.

Then repairing or replacing the locating-pin would seem to need withdrawing the spindle from the two bearings….

 

I think the pin has sheared, leaving just enough to engage the collet groove, but as the collet taper reaches its closing point there is still just enough play to allow the collet to ride up on the stub of pin, become disengaged then turn enough to jam by trapping the stub between the the two taper surfaces.

Why though this should also sometimes make withdrawing a collet difficult, I cannot work out. It seems to act as if the collet is dropping onto something.

[DiogenesParticipant @diogenes]

Nigel, is it possible to post / provide a link to a picture of the spring housing arrangement..?

[Michael GilliganParticipant @michaelgilligan61133]

A visit to this forum post by RussB would probably be useful, Nigel:

Myford VMC mill

MichaelG.

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Edit: __ Apologies for wasting your time !

… I see that you already have the document; and that [regrettably] it illustrates the Morse Taper version.

[VicParticipant @vic]

“Interesting, his saying some machinists reckon the locating pin is not necessary. I am not convinced by that. If it’s there who am I to argue with the designer of both the machines and the tooling?”

I’ve read this a few times. It seems having a broken pin is quite common on some machines and many don’t seem to bother fixing it.

[Nigel Graham 2Participant @nigelgraham2]

Diogenes-

I’ll see what I can do, but I doubt it would be any more informative than the manual’s diagrams.

Essentially the spring is wound into a cylindrical case with a flat disc cover held on by three screws. The inner end of the spring in slotted into the pinion shaft; the outer end seems to be connected to the cover.

Adjusting the tension entails removing the screws and rotating the case – a very fraught procedure.

(Many bench-drills used something like a ratchet arrangement in the cover, but this milling-machine is not that sophisticated!)

The quill pinion is accessible only by removing the head from the turret.

 

Vic – 

Now I know where to look, I did find the sorry remnant of the pin, little more than a wart on the spindle wall. At least I now know what’s in there so may find it easier to insert the tooling. I think the problem is that the wart is so low that it is possible to twist the collet round before the taper engages enough to keep the slot engaded. So when you try to tighten the drawbar it fails because the collet is now not concentric with the spindle and the taper jams on the wart.

Unfortunately the pin is covered by the spindle bearings, or is just above them, not by a removeable ring as on the machine shown in the video above.

 

I wonder if the pin, at least on the Bridgeport though likely not on the copies, was intended as a shear-pin as well as a drive key? So made to be relatively simple to replace (definitely not on the lower-cost copies.)

[BazyleParticipant @bazyle]

Unless it has been made incorrectly the locating pin is supposed to be on the parallel part not the taper so that it engages the collet almost immediately you start putting it in. Some quills will have a slot in the side to access the slot in a MT spindle version for an ejector wedge. This slot might give access to the back of the pin if the designer had more than one brain cell.

[Nigel Graham 2Participant @nigelgraham2]

The pin is where it should be. I can feel it, but there is no external accss to it.

A Morse-taper tang slot is way up at the other end of its spindle; but an R8 spindle does not have this feature anyway. It’s not fair to blame the designer for not providing a tang slot in an R8 quill; but it is fair to blame him for not providing a ready way to replace the drive-pin in said spindle.

Or perhaps not drive-pin. It will act as a crude key but I think its real function is to hold the collet when manipulating the draw-bar.

The point though is that while the video showed me where the pin is, that was on a milling-machine provided for its fairly easy replacement. When I explored the Myford’s equivalent, I found the pin is behind or above the spindle bearings.

It could be my only hope is that it is possible to reach it by removing the entire quill from the machine, but so far it seems not. The spindle and its bearings are designed to stay in place for the life of the entire machine, though, with no non-destructive way to remove them from the quill.

[Nigel Graham 2]

On Nigel Graham 2 Said:

.. …The spindle and its bearings are designed to stay in place for the life of the entire machine, though, with no non-destructive way to remove them from the quill.. …

I don’t believe that can be true – bearings are a common service item, and the VMC has a very conventionally-designed spindle/drive unit; there’s nothing in there that is more complex than a drill-press..

 

[Nigel Graham 2]

On Nigel Graham 2 Said:

The pin is where it should be. I can feel it, but there is no external accss to it.

A Morse-taper tang slot is way up at the other end of its spindle; but an R8 spindle does not have this feature anyway. It’s not fair to blame the designer for not providing a tang slot in an R8 quill; but it is fair to blame him for not providing a ready way to replace the drive-pin in said spindle.

Or perhaps not drive-pin. It will act as a crude key but I think its real function is to hold the collet when manipulating the draw-bar.

The point though is that while the video showed me where the pin is, that was on a milling-machine provided for its fairly easy replacement. When I explored the Myford’s equivalent, I found the pin is behind or above the spindle bearings.

It could be my only hope is that it is possible to reach it by removing the entire quill from the machine, but so far it seems not. The spindle and its bearings are designed to stay in place for the life of the entire machine, though, with no non-destructive way to remove them from the quill.

The Quill on the Myford VMC is serviceable and not sealed for life. I dismantled the last machine I had to change the bearings for better quality ones and to replace the Key which you are talking about. Except in my case it was the remains of a broken Tap. As these keys are supposed to be threaded on this machine. Basically a grubscrew with a spigot on, or better still two flats.

The Quill is removed by first releasing the return spring housed on the opposite side to the handle. Be prepared for this item to revolve when you take the last screw out. Mark the housing so that it can be returned with the correct pre-tension. Be sure to have the Quill lock “ON” or that will drop once the tension has gone off the feed pinion. Which in turn will make the handwheel / feed levers rotate and give a heft whack to the forearm.

The down feed pinon can then be removed completely. Releasing the Quill lock should allow the Quill to slide down. If you have any auto ejection device on the splined end of the spindle this will need to be removed as the splines have to pass through the drive pulley.

At this point you might find why the Quill has become tight. The Quill housing is made of Cast Iron and the Rack machined in the Quill which is driven by the down feed Pinion might well have damage to it and is scoring the Quill housing.

Once out access to the Spindle is via a Ring Nut and locking plate. Undoing this will allow the spindle to come out of the bearings. The bearings are standard Shielded Ball bearings. I think from memory they are only Shielded on the one side. Not good as the inside of the Quill is just a rough cast surface with all the impurities that goes with this. It would be a good upgrade to fit double shielded bearings, be that metal or rubber, but bear in mind the lower shield is exposed to hot metal chips.

Re-assembly is just the reverse of the above, but do not overtighten the Spindle bearings. They just need to be adjusted to remove any trace of endplay, no more.

I hope these notes help,

My best regards

Gray,

 

[Nigel Graham 2Participant @nigelgraham2]

Thankyou very much, Gray!

That suggests I needn’t remove the entire assembly from the machine, which would be a difficult and heavy operation.

Using the knee with a wooden pad on the table to control lowering the released quill, and aid its refitting, might be the safest way if there is sufficient headroom, though I suspect there isn’t. I’ll look at arranging some sort of cradle for use with the overhead hoist.

It’s the return spring that worries me most. There appears no way to control it properly once the screws have been renoved, giving me nightmarish visions of it suddenly slipping out and hurtling away into some inaccessible hidey-hole – or into my face. Then be impossible to refit without a clock-maker’s spring-winder (the relaxed coil being then too large).

I’d assumed the correct tension on refitting is that which will gently raise the quill with something relatively heavy like a drill-chuck or boring-head mounted. Its present tension is meaningless because even when fully tightened the quill still has to be pushed back up with the handles.

 

It does have an ejecting drawbar, which I made as such by opportunity when I had to replace the original plain drawbar that somehow disappeared in a house move – I’d had to move my machine-tools as “kits”. It has a long nut and lock-nut pair on the top end, and I think from vague memory, with these removed the bar comes out of the business end of the spindle. I “designed” it from studying the shape of the spindle in the sectioned view in the manual. The two nuts, forming the draw-bar’s “bolt head”, sit on the rim of the spindle but might be just small enough to pass through the pulley splines. Errr, surely they must do otherwise it would be impossible to lower the spindle in normal use! They certainly disappear from sight.

 

I may have to delay these repairs a little while as I’m presently engaged in work for the club, needing occasional, ad-hoc milling; but they are needed because the problems are worsening. By finger, the stub of the broken pin is so small it’s a wonder it is able to do anything useful. While the sticky quill removes all sensitivity for drilling.

[DiogenesParticipant @diogenes]

It looks like the cover has an extended rim on the inside to form a housing for the spring – once in a relaxed condition it should stay there unless carelessly handled…

 

[Graham MeekParticipant @grahammeek88282]

When I removed the Quill from my machine some 40 years ago. I undid the bolts that allow the head to be tilted over. This allows the Quill to come out easily in the horizontal mode. The fit between the Quill and the Quill housing is fairly good and you need to be able to “feel” the Quill sliding in. Trying to do this with the aid of the knee would not be good. You can always wiggle the part back out if it gets stuck. You will not be able to sense this when using a mechanical assistance.

Hope this eases the job.

My best regards

Gray,

[Nigel Graham 2Participant @nigelgraham2]

Progress…

Of sorts.

I found the quilll spring is indeed in a nest which comes out easily and safely with some care.

Four screws on the side of the head and the pinion slides out.

Remving the quill was the hardest part. It would not slide under its own weight, including that of the spindle. until within half an inch of the exit. I didn’t need remove the home-made ejecting drawbar as its 3/4″ AF head is within the spline roots.

To dismantle further I set the assembly up on the Harrison lathe, gripping the spindle nose in a 3-jaw chuck and supporting the top end by a centre in the centre-hole of the drawbar. Wangling the locking-plate off took a bit of doing.

The spindle came out of the top bearings, and the lower bearings out of the quill, with a bit of effort. The thrust-bearing came off easily.

 

So now I could search for the broken pin, its tip now visible inside as just a bump on the wall. And yes, its outer end is nearly covered by the radial bearing, which is extremely tight on the spindle.

I am not sure how to remove that without harm. I will try plumber’s pipe-freezing spray on the spindle to see if that will give a micron or two less grip. For re-assembly I’ll pop the spindle in the freezer overnight, and perhaps warm the other parts gently in the oven. Not enough to run the grease out, but perhaps giving half a thou extra.

 

The upshot is that the quill problem is not curable. There are no signs of scoring or rubbing. It is just too tight in the bore.

The pin problem is curable only if I can remove the bearing.

[duncan webster 1Participant @duncanwebster1]

As a last resort you could try one of those 3 leg hone things that are used for de-glazing car engine bores, but I very much doubt myford let it leave with the quill too tight.

[DiogenesParticipant @diogenes]

Don’t be tempted to ‘ease’ anything yet!

Whilst it is disassembled, try the ’empty’ quill up the hole with the aim of establishing whether the binding is in the lower ‘quill’ part of the assembly, or whether it’s in the upper ‘spindle-drive’ area.

 

[Graham MeekParticipant @grahammeek88282]

If the down feed was OK in the beginning then something has changed during use.

Check for bright spots of wear on the Quill Housing, these are the high spots. Is there any congealed oil on the Quill Housing. Shellac type deposits are going to take up the clearance between the Quill and its Housing.

My first thoughts were as I said earlier. Damage to the teeth of the Rack on the side of the Quill Housing. Any slight burring to the tops of the teeth at the edges where these meet the diameter of the Quill will cause tightness.

Similarly if at some point by a previous owner may be, the Quill lock has been applied a little exuberantly this will distort the soft cast iron Quill housing. This will definitely lead to tightness.

I would procure an Arkansas slip stone, (4″x1″x1/2″) and rub this over any bright spots, any damage to the teeth and especially in the area where the clamps act upon the Quill housing.

Have you tried the fit of the Guide Bar in its slot?

Thoroughly clean every thing after with some solvent spray. Then gently try the parts dry. If every thing is OK just lubricate and reassemble.

As regards the bearing I would sacrifice this and replace it with a new one as you have the spindle apart. It is always easier to mount a new bearing than get the old one off. I suspect a puller will probably Brinell the bearing anyway as pressure really needs to be applied to the inner track for removal and insertion.

I am just thankful for you that you did not find any scoring of the Quill housing.

I hope my further notes provide a solution.

My best regards

Gray,

[BazyleParticipant @bazyle]

Do try and get some photos please as this doesn’t seem to be covered on the internet yet. A world first!

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