Myford S7 Cross Slide Question, Perhaps Applicable to Others

[SteveW]

Guys,

This is something that's been bugging me for years. I have repeatedly adjusted the cross slide lead screw back nut, the allen cap secured round nut up behind the alloy casting, to be just tight enough to eliminate back lash but not too tight to impede movement or be notchy. My problem is that routinely its not quite tight enough to prevent the dial settling off datum when I look away.

Is anyone here aware of some clever little damper gizmo that can be added that will provide some form of definable braking to the lead screw while allowing full and free dial rotation. I'm not looking for that needle thrust race solution available from one of our suppliers.

Having just got hacked off enough to give the thing a serious look the only solution I can see is to add a springy steel yoke, secured by the two allen caps that hold the lead screw system to the front of the slide, that then supports some sort of brake material to rub against round back nut. This should avoid making any other holes in the thing or compromising the actual lead screw assembly and a major strip of the whole assembly.

[uuu]

I thought there was a wavy washer between the dial and the ball handle, that provides enough friction to keep the dial in position. Could you add a similar thing under the adjustment nut which, when done up to be completely flat would add tension, without any extra backlash?

Wilf

[ettingtonliam]

A fibre washer or a Bellville washer under the adjustment collar?

[92220]

As Wilf says, there should be a wavy washer in place. It really works wonders. Unfortunately I had a couple of ex-Myford guys come to service my lathe. I didn't notice they hadn't replaced the wavy washer and it is a bloody pain now, with no restriction whatsoever. the dial can be spun around!! Must get a new one. RDG Tools have bought the Myford rights and apparently are making Myfords again. I must chase them for a replacement wave washer.

Bob.

[SteveW]

I did consider the wavey or fibre washer (above) but discounted it thinking that it could bite my bum when boring, i.e. when pulling the saddle outwards. I've also been fly cutting stuff recently which, given the range limits of the cross slide, had me driving in both direction.

The more I think about it the least 'spring' or backlash possible is best and in both directions. This means some sort of braking system pushing on the round adjuster nut that opposes the dial.

Looks like I need a 'Y' (or 'V') shaped bit of springy sheet steel with the top ends of the 'Y' bent up at 90° with holes or slots that match the spacing of the two allen caps holding the dial assembly to the saddle. The foot of the 'Y' would have a friction pad to bare against the round nut. Q.E.D.

Thanks for the thoughts and watch this space for developments.

[tony9f]

Hi Steve,

I sympathize with your situation in this regard. For many years I found the standard method of adjustment an irritation on both the cross slide and the top slide and although it takes a bit of effort fitting needle races transforms the action of the slide. The adjustment can be set so that there is no slop at the leadscrew bearing yet gives smooth operation.

After fitting some needle races to the leadscrew thrust and noticing the improvement I then carried out the mods to the cross slide and top slide. The top slide now travels easily without sticking which is great for taper turning.
I have to add that I fitted a new cross slide leadscrew and nut as after 40 odd years there was a lot of wear in them.

Not wanting to put the mockers on it but I don't think there is any really easy way to solve this problem.

Tony

[SteveW]

Oct 13, 2023 11:17:02 GMT tony9f said:

Hi Steve,
(snipped)
After fitting some needle races to the leadscrew thrust and noticing the improvement I then carried out the mods to the cross slide and top slide. The top slide now travels easily without sticking which is great for taper turning.
(snipped)
Tony

Just found this on the ArcEuroTrade site: ML7 Mod.

The text adds that this particular mod isn't for the S7. However there is scope for this. Perhaps the biggest hurdle being one needs an operational cross slide necessary to machine one's cross slide bits.

Another aspect is I want to avoid making holes in what is classic but simple old lathe.

(164)

[uuu]

Perhaps, once you've got the leadscrew running smoothly, you could tighten the gibs a little, so more force is required to knock it off a set position.

Wilf

[tony9f]

Steve,

I carried out all my modifications discreetly and you would not know from looking at the lathe that anything had been done. It is only when you look under the slide that you can see the thrust races. It is easily possible to have the bearing mounted in the brackets so as to be undetectable and leave the lathe looking as original.

If you are interested in what I did I can send you details and pictures via. email.

Tony