ML7 tailstock angle alignment adjustment

Hi, does anyone have this tailstock on their ML7 lathe. I've been trying to adjust the tailstock angle for the last 5 years or so, it's 2 thou out on the test bar. Looking for someone who has this tailstock and can readily see adjustment occurring on their parallel test bar. Obviously I've tried a lot of things so far - the two rear slotted screws and the two allen heads holding the pinch bar all do not change the angle, they just snug down the movement of the tailstock. I've stripped it all down several times and had everything out to investigate but so far nothing changes the tailstock angle at all. I've tried different parallel bars and fixed centres, all read the same. Also tried reversing the pinch bar, to no effect. This is a new old stock lathe from the 70s. Thanks

Phil

Edited By Phil West on 01/02/2019 09:37:22

The two slotted screws at each side control the position of the tailstock. Just loosen one side screw and tighten the opposite side and the tailstock moves in one direction.

Doug

Hello Phil,

I think you have overlooked the two small screws either side of the tailstock, fitted just above the cross tongue. They are used as a pair to push the tailstock across the bed to change the set-over angle.

Free them both off so that they are no longer tight, and then tighten one slightly to shift the tailstock bodily across the bed. I don't know which direction you need to move it in to restore parallel position but with your test bar fitted you should be able to detect the movement on a dial gauge. By these means you can iterate down to the position you want to achieve and having got there, tighten the opposite screw to lock the position.

I hope that helps

Brian

PS Douglas got there ahead of me

Edited By Brian Wood on 01/02/2019 09:48:03

Edited By Brian Wood on 01/02/2019 09:49:33

Tried that unfortunately thanks - about a thousand times. Tightening the one towards the front does actually move the angle - although as soon as you move the angle you have tightened the pinch bar to the lathe bed and the tailstock no longer slides on the bed. And in addition it moves the tailstock the wrong way. The rear screw does nothing - the angle does not change at all whether you tighten really tight or remove that adjusting screw completely. All that screw does is tighten down the pinch bar so the tailstock no longer slides.

What do you mean by "angle"? The tailstock's axis should be aligned parallel to the h/s axis by manufacture and isn't adjustable on the Myford. If yours is actually angled then you have a difficult problem to fix!

But when you say it is "2 thou out" that implies that it could be parallel but is offset. Doug describes how to use the slotted screws to adjust the offset. The easiest way is to put accurate centres in h/s and t/s tapers, move the t/s up to the h/s and trap a thin short steel rule or similar between the points, and adjust the screws until the rule is at right angles to the axis.

I've not seen the little offset scale before, my S7 doesn't have it.

I believe the screws are to allow adjustment of set-over (front to back position) of tailstock - NOT the angle of tailstock to the bed. If you try to twist the tailstock it'll simply bind on the slide.

Exploded diagram on Myford site could be clearer, looks to me like the screws at the ends are for adjusting the Gib.

Edited By David Jupp on 01/02/2019 10:01:20

Phil,

Are you confusing one set of screws for the others that are at the front and rear positions on the bed shoe and on the side opposite to the operator?

The rest of us are talking about the pair just below the axle that the clamp for the bed is suspended from

Regards

Brian

Edited By Brian Wood on 01/02/2019 09:58:26

My 1960s S7 does but I left it off when I refurbished the lathe as I found it of very little practical use.

PS It occurs to me that this kind of discussion would be more fruitful if the nomenclature and numbering of parts in the manual were used.

Edited By ega on 01/02/2019 10:06:57

Brian - the simple answer to your question is ***yes***. Great stuff many thanks. I turned in the screw facing me under the clamp axle and the dial indicator moved 2 thou in the correct direction. Now when I run the dial indicator back and forth along the length of the parallel test bar it stays dead on the same reading the whole way.

Thanks all for your responses, much appreciated!

The other point is that you need to back off the screw on one side so you have room to tighten the opposite screw.

Phil,

Nice to hear your reply and I'm sure we are all glad that the your problem is solved

Brian

Phil,

May I suggest that you obtain a copy of the official Myford handbook for your particular lathe. Myford hand books are excellent and tell you all you really need to know about adjusting and maintaining your lathe and can therefore save you a lot of trouble.

Copies are available from "New" Myford or even free as pdf from the net.

Eric

Ok thanks Eric - will do.

Now all you need to do is turn a test piece between centres and measure it for parallel. Ground test bars don't tell the whole story on old worn machines. The proof is in the actual turning.

You will find too that the square piece of key steel on the bottom of the tailstock can be adjusted to obtain a neat fit in between the two inner lathe shears. If the bed is not worn, you set it at the tailstock end and the fit should remain the same along the full bed. If the bed is worn (more common on the pre-1972 "narrow guide" models) there will be excess slack in the worn spot toward the lefthand end of the bed ways. This can throw your tailstock offset out by however much the wear is.