MYFORD S7 Power Red Cross slide movement

Hi noticed Myford wasn’t cutting great , on inspection found cross slide had front to back movement so adjusted adjusting collar as much as I can with out it sticking but still has tiny tiny movement is the normal or do I need a new feed nut , and can you get just a feed nut as only seen with metric with a feed screw , one on mine is the old grey type not brass ..

or is there any other adjustment I can try or tricks etc

many help most appreciated

Thanks

Yes that movement is normal and will not affect the finish of your cut. It is due to the usual backlash between the cross slide feed screw and the nut.

Cause of poor cutting could be any of more than a dozen other things: eg slack in headstock bearings, blunt or chipped tool, tool height, cutting speed, feed rate, poor piece of material, worn bed, gib strip adjustment on topslide, cross slide or main carriage, etc etc.

Edited By Hopper on 10/06/2023 10:10:12

Beware setting 'tiny tiny' movement on a bog-standard anti-backlash adjuster because keeping them tight causes severe wear. It's usual to accept a moderate amount of backlash, and either remember to compensate for it or fit a DRO.

Feed nuts don't last forever and it may be worn out. The only way to find out if it's causing poor cutting I think is to take the slide apart and inspect it. Backlash in itself isn't normally a problem, so see Hoppers list.

I suspect replacement nuts only being available in metric is a temporary out-of-stock thing - most Myfords are imperial, so perhaps all the imperial spares have been bought, and replacements haven't arrived yet. Brexit, Covid, and the Ukraine have disrupted world trade quite seriously and intermittent shortages aren't unusual at the moment.

Dave

THANKS

seems a lot better since I adjusted it may of needed a little adjustment or came loose .

seems odd that Myford didn’t think of this as my 40 year hobbymat has zero movement/ backlash ,

as most other stuff I’ve seen has an adjustable nut thing some where ..

The reason Myford didn't bother is that it was never considered particularly important on a lathe . On a mill you are moving the table back and forth in all directions and working to X.Y co-ordinates so backlash can/will lead to errors. But the cross slide on a lathe is generally wound in progressively in one direction until desired diameter is reached, so backlash does not cause errors. And it won't cause poor finish or poor cuttting as once cutting begins, the cross slide is pushed outwards by the cutting forces so all backlash is taken up.

Thanks all seems ok now little adjusting ( as not sure it’s ever been done ) and a new cutting tip 👍

Feed screw & nut for power cross feed are sold as a matched pair. I converted my S7 PXF from metric to imperial and the new components supplied by Myford and changed three times suffered from tight spots and I will convert back to metric as the feed screw and nut were perfect and I now have fitted DRO.

Robert Butler

Backlash is a fact of life for any screw thread. Numerical Control and then Computer Numerical Control demanded backlash free screws and the popular solution is recirculating ball screws, hydraulic rams were also used on some machines and robots. Backlash eliminators were fitted to some mills to enable climb milling to be used. The crude split nut solution is not overly satisfactory as the screw usually wears unevenly so will have tight or loose areas. Other more complex solutions are available. Even expensive machines where great care is taken to fit screws and nuts will eventually succumb to wear and our friend backlash will appear. I am surprised or even amazed that you have zero backlash on your hobbymat, does it have something like Delrin nuts? Or some other solution.

Mike

John Fletcher. I replied to your email concerning the DRO fitment to the S7 and it is unopened.

Robert Butler