Member postings for John D

Does anyone know the ideal belt size and profile for the Myford VMC. The manual states A34 and B31 but having ordered these it’s clear that the B profile is too large and they should both be A. Existing belts are 800mm and 890mm respectively but no reason to believe they are correct and the rear belt getting warmer than I’d like.

If anyone knows for sure what works that would be great.

Cheers John

Been a busy week. I’ll measure the threads and head on the lower shaped ones when I can get down the to the workshop.

I’m now sure the top ones are Van Norman V5. Does anyone this side of the Atlantic use them do you think?

There are indeed two sets mixed up. The upper photos appear to show the majority to be V5 collets (Van Norman #5) from the dimensions and the notch in the taper. The lower ones are still a mystery.

I have about 30 imperial collets that I thought at first glance were 5c (not at that stage knowing anything about 5c collets!) and now having looked at them more closely I have two different types, neither 5c. I wondered if anyone can identify them from the photos/ (very) appx dimensions? Many have double c logo on them. Other markings are difficult to make out but in addition to sizes I think I could see 664.  Not sure if they are of use to anyone.

Edited By John D on 24/06/2023 22:37:26

Edited By John D on 24/06/2023 22:57:06

I hope it's ok to revive this thread form a couple of years back - there's not much info in these on the web so the photos and info above is really helpful, thank you. Having just got one of these I am going to strip it down and give it some tlc. Does anyone know how to remove the chuck and what type of fitting the chuck is. I am assuming it is a J0 taper as it's a No. 0 Jacobs chuck.

Edited By John D on 18/06/2023 16:15:41

Thank you, I think I felt like that might be the answer but hoped not! I have metric er32 and imperial and metric r8 so just wondering whether to get involved in 5c for through holding work pieces.

I have happened across a full set? (30) of imperial 5c collets. How many metric collets and which sizes do I need to get to make it a full set that can do pretty much anything in the standard range? I am hoping I don’t need a full set of metric with some near as damb it the same?

Edited By John D on 17/06/2023 18:56:41

Some good news. I think I have now reduced runout to a workable level.

I cleaned everything, and ordered new bearings. When testing with various methods and setups I was clocking run out at .005mm on the bench. Fitting the lower bearing to the shaft was difficult. Even having heated the bearing up to 80 degrees C it was still difficult getting it onto the shaft. I drifted it on and it took more effort than i would have liked (from the point of view of risking damage somewhere). I used SKF bearings other than for the thrust bearing where I used NSK as this was readily available. The thrust bearing was subtly different in that the one of the 'washers' was an tight fit on the shaft whereas the other just slipped on. I put the tighter one in the lower position (i.e against the face of the lower bearing) as I assumed that this one should move with the shaft whereas the other contacts the step in the quill.

I tightened the nut the at the top of the quill so is to created just the slightest amount of resistance when turning the shaft by hand in the quill. I then backed it off and re tightened it once again slightly less to again just the start of perceptible resistance. Is that correct? How would i know if it was too loose or tight?

All done I am now getting .01mm runout measured at various points on the lower taper. I don't have a long enough knob piece for my indicator to measure the upper surface on the R8 at this stage. Next step is to use a collet with a ground bar and measure 200mm down from the nose and see how things are looking - but I am really pleased at this stage.

Doing my time again I would have heated the bearing for longer (in the oven) to more like 90 degrees C before fitting to see if that reduced the problems fitting the bearing to the shaft and therefore reduced the chances of introducing some runout at that stage by rough handling of the bearing while drifting it on. I'm not sure its worth stripping again and buying new bearings to find out.

I don’t have access to a press but think that may be my best option. I just need to find someone with a press near me (Herts/Bucks).

Tony, you make a good point about how I measure. How should one get bearings on and off a shaft without damaging things? I could heat the bearings or chill the shaft I guess.

Edited By John D on 15/11/2022 21:13:53

Hi Lathejack

starting from the bottom up:

At the bottom end of the quill

1 x 6207zz (confirmed on removed bearing)

1 x 2907 thrust (from myford manual)

at the top of the quill

1x 6206zz (confirmed on removed bearing)

and then, I think, under the pulley

2x 6009zz

Edited By John D on 15/11/2022 20:57:55

Thank you all for your further replies. I have now managed to strip down the quill and spindle which was indeed very straight forward. Placing the spindle between centres on the lathe I am getting in the range of .0075-.01mm runout in the centre. I am getting the same when testing with it on two vee blocks. (Supporting it on the lathe on a centre in the spline and and on its bearing on the other I was getting pretty much no run out in the taper.). I have therefore concluded that it is indeed very slightly banana shaped.

Spindle services prices were reasonable for a simple taper regrind but climbed to well over 1k if doing anything involving bearings too.

Any thoughts on straightening this fairly small amount without machining would be welcome. New bearings are on order.

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

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.

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.

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?

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.

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

Thanks Martin. I’ll go front for x as you suggest. I’ll cut a large chamfer on the back of the L bracket that the encoder mounts on so it clears the oiling points and that way the rail can sit nice and flat just above the two oiling points.

i don’t have any captive bits for the dovetail so hoping I can find a ready source for them. Does anyone know if all the variants of these VMC have the same dovetail size in the front?

I thought I’d drop a quick update on progress with the DRO install.

The Y axis is done, the knee Z axis is done. I am procrastinating about whether to go front or rear for the x axis. I don’t mind losing the stops but don’t like the vulnerability of having it on the front - but equally I don’t want to lose y axis travel unnecessarily. Also, does anyone know the angle of the dovetail on the front of the table? Or better still where dovetail nuts are available from (I could just by a dovetail cutter I suppose)?

I decided to go with the idea of a combiner and an addition Z axis encoder on the quill. It will only be tiny but a nice addition and not much more money thanks to Tony and Jo at M-DRO.

I’m looking at no-drill mounting options for the quill scale and thinking a machined plate to replace the cap on the left of the head and then a mounting on the top inch or so of the existing scale for the encoder.

Edited By John D on 16/10/2022 18:25:02

Thank you so much for the replies. Knowing it is likely normal experience means that I can leave it for now and focus on completing the DRO install.

John, I would prefer to avoid cutting the paint on the gear shaft sleeve. The backlash must be a feature of the fore/aft position of the horizontal gear in relation to the lead screw gear. I’m therefore hoping that it would be possible to adjust this without removing the sleeve / housing. It was all much more accessible when I had the knee off. Perhaps the same take up in free play could be achieved by doing what you suggest regarding skimming and fitting a washer but in the process making the washer a shave more than the amount taken off. Or reversing the gear and doing the same. 

Edited By John D on 16/10/2022 13:48:09