Myford VMC Spindle Advice Please.

[Graham MeekParticipant @grahammeek88282]

Hi Nigel,

I am glad to hear you are making progress.

There was no guarantee the Spindle journal was truly round before you started. Unless the Centre cones of the Spindle were lapped before Cylindrical Grinding, then this will affect the quality of the ground journal. The scuffing is normal and is probably very fine left-over grit from the abrasive.

A layer of Molykote GN paste or similar on the journal will prevent any scuffing.

With the Ring nut applying pressure to eliminate end-play on this inner member of the bearing, (33), it will not rotate on the Spindle journal. Friction between the locking washer and the end face of the bearing will be too great. The journal is acting merely a location device for the Bearing. It will be far easier for the bearing to rotate on the Bearing Balls as intended, than to try and rotate the inner member.

Good luck with the rebuild,

Regards

Gray.

[Nigel Graham 2Participant @nigelgraham2]

Thankyou.

With no way of knowing how tight the ring-nut should be, I tightened it fully then backed it off by perhaps a quater-turn. I could not detect any end-play.

The quill’s back in the machine.  Luckily I had spotted the circlip had come off the end of the pinion shaft but had not vanished. I don’t know how that happened but its groove is quite shallow.

I don’t know the “correct” return-spring tension so left it just returning from the lowest quill setting but needing a little help near the top – certainly far better than it had been for years.

(The equivalent on my Meddings bench-drill is quite fierce, needing a restraining hand on the handle when I use the machine, rotated by hand, as a tap-driver.)

 

Another area for attention is the quill-lock.

I don’t think that was releasing properly. The end of one half seemed burred, and it was glued by oil residue too.

Re-fitting it, I added a washer to alter the handle’s radial position when locked / unlocked. When it’s loose I want the handle to lean away from the depth-stop a bit. Previously it tended to fall under the stop-block, rather like a single-tooth ratchet and pawl, obstructing lowering the quill.

Then I dropped the little handle, saw it roll under a trolley. I moved the trolley and there it wasn’t. Gone. As if it never existed. At least my search discovered the awful little thumbscrew that had fallen from the table handle dial, and an oil-cup I think I’d had to remove to fit the DRO’s involved bracketry.

[Graham MeekParticipant @grahammeek88282]

Hi Nigel,

Thank you for letting us know your machine is now functioning properly. The Forum does not seem to get much feedback these days as regards solving members problems, and I am glad my scribblings have helped you through the problem.

Some years ago I made it a policy of putting what is in essence a skirting board around my machine and bench bases. Thus “stopping up” any potential escape route for unruly parts. It never ceased to amaze me whilst working, how dropped items would always go under the bench. After all there were two options.

 

Regards

Gray,

[Nigel Graham 2]

On Nigel Graham 2 Said:

 

[…] Another area for attention is the quill-lock.

I don’t think that was releasing properly. The end of one half seemed burred, and it was glued by oil residue too. […]

A very common problem when restoring microscope mechanisms

… I have found PlusGas ‘formula A’ to be an effective solvent/cleaner

MichaelG.

[DiogenesParticipant @diogenes]

That sounds good Nigel, should be much better to use.

For the (?similar?) split cotter quill-lock on the Major I inserted two-or-three turns cut from a coil spring between the halves to just to help them lift off – the movement between ‘loose’ and ‘firmly-locked’ being very small.

[Graham MeekParticipant @grahammeek88282]

Some form of release mechanism is a good idea with this type of clamp.

With use these Pads can get that they wedge themselves between the Quill and the Housing. Especially if the radius used is slightly larger than the Quill. These Pads would not be line bored in-situ, like a Home Machinist would do it, but machined as a stand alone part until assembled.

Emco overcame this problem with their larger Mills by using a 45 degree flat instead of the semi-circular cut-out as used on the VMC. This gives line contact and less chance of the clamp to stick.

Regards

Gray,

[BazyleParticipant @bazyle]

Incidentally on another forum today someone mentioned that bolting a Bridgeport mill head (presumably pretty solid compared to a VMC) to a non flat support (for maintenance) can make the quill stiff to operate.

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