VMC Mill spindle runout

What kind of runout is typical/ acceptable on a Myford/ Warco VMC mill spindle as measured on the bottom of the spindle taper? I'm getting 0.035mm and not sure if that's terrible and if so what I can do about it?

Edited By John D on 13/11/2022 14:19:34

About 10 times worse that I get on the X3, thought Myfords were built to a better standard than the far eastern machines or maybe that is only if you can find a good second hand one..

It's not that good. For example I often run with a chip load of 0.02mm per tooth so if I was using a 2-flute cutter it could well be acting as a single flute with one flute taking almost all the cut and the other just rubbing on the surface.

Not familiar with how they go together but I'm sure someone will be along who has one.

Hello John,

That doesn't sound good to me. Have you tried a taper shank drill in the socket to see what happens at the tip of the drill? Is the effect progressive or confined to a particular area?

As to recovery, before you do anything take a very good look to see if there is local bruising at the mouth of the socket in which case a taper reamer may well be all you need to whip it out and clean it up. Not easy working upside down to check progress so it may help to grip the tang in a drill vice and hand hold the combo where you can better feel and judge any 'orbital' effects and bias the action accordingly.

Best of luck Brian

Thank you for the reply, Brian. It's an R8 taper and I don't have any R8 drills, only ER32 and Clarkson Autolock collets. I don't seam to be getting much worse a reading when the quill is lowered. I have measured on the inner edge of the taper and the outer edge of the spindle nose and get the same reading. I bought it from a guy who i thought reputable and well thought of on here. I've spent ages fitting a 3 axis DRO and now gutted to find this.

I can't find much info on line about the Myford Taiwan imports and which other branded models might share the same spindle. (e.g. it doesn't have fine feed quill) Is there any way of re-machining the taper to take out the runout? Is replacing the spindle the answer - if indeed i could find one? The parts diagram is pretty unclear - i'm not sure how to remove the spindle.

No reason why you can’t remachine the R8 taper on the mill itself, just swing the head over to the correct angle and clamp a carbide tool in the machine vice. If you can borrow a toolpost grinder or a Quorn grinding head you could set that up on the table and grind it.

Hi John

It is quite possible to remachine the R8 taper on the machine itself by tilting the head at half the included angle of the R8 taper and using a boring tool fitted to the table and feeding the table up to advance the cut. I've done it on a couple of old Bridgeport clones at work that had very damaged tapers from misuse. But it's a fiddle to set up and not for the faint hearted.

But and this is a very big but, only as a very last resort, If the spindle has been bent somehow, and it does happen then the bearings will be under strain due to misalignment, the best way is to dismantle the spindle checking for straightness, which will also give an opportunity to check and regrease the bearings. I have dismantled a VMC spindle to replace the thrust bearing but it was a long time ago, but don't think its too difficult a job.

I'm sure someone will come along who's dismantled one of these and can remember the specifics, but I would stress don't attempt any remachining or drastic action until everything has been checked, If you are anywhere near Folkestone in Kent I'd be happy to help with the checking. I had a Hayes diemaster milling machine with a bent spindle a few years ago and a company in Coventry, Spindle Services completely rebuilt it with new bearings,and reground the 2mt taper for a very reasonable amount, so all is not lost there is proffessional help available.

Good Luck

Dave

As an afterthought if you have a collet and a length of bar that is known to be straight, or preferably a ground test bar you could see if the runout changes at a distance from the spindle nose, not an exhaustive test but would give some indication. I don't think Myford would have let it leave the works with that level of runout.

Edited By Dave Wootton on 13/11/2022 16:48:08

Before getting to drastic I would suggest checking the bearings are correctly adjusted and then test the runout without the belt connected.

Not sure that will work, what about the plain diameter further up the spindle?

Has the OP measured the run out of the plain diameter? Not easy to do what with it being "down a hole" and the key in the way.

Hello again John,

Ouch! Obviously my plan is not viable and with respect to Baz, I don't think his plan is as easy as he makes it sound.

Have you spoken to the man who sold it to you? It would be fair to get his reaction rather than try to correct matters yourself.

Brian

Posted by John D 13/11/2022 15:58:27

Thank you for the reply, Brian. It's an R8 taper and I don't have any R8 drills, only ER32 and
Clarkson Autolock collets. I don't seam to be getting much worse a reading when the quill
is lowered. I have measured on the inner edge of the taper and the outer edge of the spindle
nose and get the same reading. I bought it from a guy who i thought reputable and well
thought of on here. I've spent ages fitting a 3 axis DRO and now gutted to find this.

I can't find much info on line about the Myford Taiwan imports and which other branded
models might share the same spindle. (e.g. it doesn't have fine feed quill) Is there any
way of re-machining the taper to take out the runout? Is replacing the spindle the
answer - if indeed i could find one? The parts diagram is pretty unclear - i'm not sure
how to remove the spindle.

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The spindle on my Warco A2F has about .0002" run out at the lower edge,the
top end the parallel part has some runout also ,i just make arbors to suit
what i need and finish them in situ as there is a locating pin they allways fit
back is the same place with zero runout.
Lowering the spindle won't make any difference to the run out reading.

It would be possible to regrind the tapered part of the spindle in its
own bearings on the machine as you can set over the head to
the required angle and use a toolpost grinder mounted on the table
providing the bearings are good , but is not possible to regrind the
upper parallel part for obvious reasons .

There is in my album for the A2F mill the complete handbook
which has a parts list ,i don't know if these machines are identical,Chester
still sell this machine as as the 830 VS so may have or be able to get parts.

John

.

That’s rather impressive !

MichaelG.

Thank you everyone. I think the Myford VMC is almost identical to the Warco VMC and Chester 626 rather than the 830 VS/ A2F. All the newer machines have fine feed quill which I assume would also mean a different spindle design. Anyone out there done the strip down?

The bearings are quiet and it runs so smoothly i trusted that all ok. I can't believe i didn't pop a dial on it. I've now not only spent all my money i've also spent hours fitting the DRO.

Finding a replacement spindle is likely impossible so living with it or getting it reground sounds like my only practical option. Does anyone have any idea on cost?

...and I just want to check - is 0.034mm far outside what most people would consider ok?

From what you say John with the outside run out it is beginning to sound as though the machine has had some kind of crash in the past. If these two run out values, internal and external are in much the same position that would confirm my thinking and left it with a bent spindle.

Re-machining the T8 taper won't put that right and new bearings will also be sensible to fit as well. Dave Wooton had knowledge of the Bridgeport clones he recut the tapers on along with run out values for the outside of the spindle so he would have known the taper was all he had to correct.

I still think you should now talk with the vendor, it is beginning to sound as though he has unloaded it

My sympathies Brian

John

I have just measured the run out of the inside of the R8 taper on my VMC type mill and it is .0003" (.00762 mm ) The mill was bought in 1983 and is not a Myford or Warco but one imported from Taiwan by an Canadian company, and has been in regular use since then.

John

I’ve spent the money and done all the work to fit a DRO and with the DRO fitted I can’t expect him to take it back. I need to find a way forward that leaves me in a workable place but don’t know what that is.

It’s very clear, John D, that the numbers you are getting are unacceptable … The question is: Do they reflect a major problem [like a bent spindle] or are they caused by some localised damage in the R8 socket ?

Without very careful inspection, you [and definitely we] will not be able to answer that.

MichaelG.

Thanks Michael. I’m given to thinking it’s a spindle problem given that the runout is mirrored when indicating on either the interior R8 face or the external face of the spindle.

Surely if the quill is bent it would not be possible to lower it? As advised before strip out the quill and check measurements or seek specialist help to check and repair?

Robert Butler

Edited By Robert Butler on 13/11/2022 20:43:15

Robert, am I right that you mean spindle rather than quill?  My plan is to remove the spindle and get some proper measurements. I just need to work how the spindle is removed.  If anyone has done this on a VMC then your guidance would be much appreciated.

Thank you all for all your help.

Edited By John D on 13/11/2022 21:19:32

I would strip the spindle and check that the bearing seatings are not damaged, it may be that the bearings have been replaced and not been seated correctly, maybe picked up or some other damage. Some careful checks should reveal where the problem exists. I doubt that the error existed when manufactured so is likely to have occurred with a crash or careless rebuild. I suppose the error could have existed since manufacture but I would find it incredible if it was allowed to be shipped without such a basic check not being made.

Mike