Myford VMC rough rise fall Z axis/ knee

I am with Baz, the sound is the same as the machine I had some years ago. The problem can be worse when the Gibs are too tight, especially when lowering the knee.

Regards

Gray,

Posted by John D 15/10/2022 21:51:34

Does anyone know if it might be possible to obtain the elevation gears for the Myford
VMC anywhere? I suppose best bet is knowing which machines it was the same as
(at least in respect of the gearing for Z axis). Mine has some roughness when
lowering the knee and, although better on raising, still not perfect. You hear a
click click click on when lowering. Everything has been cleaned but i cannot
see any way of adjusting the gears.

Wondering if they are all like this?

Photo of gears cleaned up and with the retaining washer and nut removed.
All greased up with fresh grease but no different.

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Those gears look about normal and are much the same on my Warco
2 AF mill ,the backlash on my machine is shown as 0.0015 " on the
index dial so you look to have excessive backlash on your machine.
As far as adjustment goes the knee and gear shaft sleeve as depicted
in the following images are 2 separate parts 102 and 105 ,i expect the adjustment
for the backlash is made on assembly after which the these parts are filled
and eventually painted over to look as one piece.
You can soon tell if this is so as if you feel up inside the casting you may
find the holes or bolts protruding.

Even if you find a supply of new gears they may fit exactly the same if
the adjustment was out from new.
It may well be possible to adjust the mesh unfortunately it would mean
digging through the filler and paint to find the bolts to dismantle and
adjust.

When i got my A2f from Warco these 2 gears were very rough in operation,
i mixed some green label fine Timesaver abrasive in with the grease and
after a short time they were as smooth as silk ,this abrasive is non imbedding
and can be left on as it eventually becomes inert , i use this grease on these
gears "Rocol 18302 Tufgear Universal Open Gear" it is more suitable.

You could turn off about 1/8" off the top of lead screw gear and refit it with
a 1/8" washer underneath likewise also with the input gear to
establish a new contact point on the gears.

John

Edited By John P on 16/10/2022 12:07:02

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