Um…are the grub screws bearing on a strip of metal of parallelogram cross section that fits in the dovetails? If so, the strip is called the "gib strip" and setting it up is critical to getting easy sliding with minimum play. There's no obvious upgrade just patient adjustment until you get reasonably smooth and easy turning requiring uniform torque all the way along the travel. Better a bit tight than a bit loose as you need to minimise play in the slide. When adjusting the screws, have a spanner on the nut so that you can tighten the screw without turning the nut, then hold the screw while you tighten the nut to lock it. Lubricate the dovetails and the sliding face of the jib with some graphite grease or similar as you assemble it.

As John said plus the pointy gib screws often have to engage with matching dimples on the inner side of the gib strip. Thus the parallelogram has to be the right way round and aligned so the screws fit properly into the dimples before tightening up. The dimples prevent the gib strip sliding and help transfer screw pressure evenly on to the bearing surface.

Once the gib strip is aligned, I tighten the screws gently by hand until they just resist turning. Then adjust as described by John. It may take several attempts to get the pressure correct across the full range of travel with no tight or loose spots anywhere.

Some people have improved the gibs of Chinese lathes by polishing the running surface, or by reshaping the dimples for a better match to the screw points, or by replacing the gibs entirely with new ones made of brass. I polished the gibs on my mini-lathe and found it made no practical difference, it was OK before and after! An ML7 shouldn't need upgrading, maybe the gibs on your machine have been inexpertly replaced or are damaged. (Who knows what adventures an ML7 has had since new!)

Dave

I did the doweling thing on my Drummond top and cross slides but could notice no difference in operation. On the ML7 we just rounded off the ends of the original Myford screw points so they were a dome that located in the dimples in the gib strip and stops them digging trenches in the gib that then allow movement. Works very nicely.

The secret to adjustment is cleanliness and burr-freeness of the gib, dovetails and whole assembly. Then adjust the screw at each end until just noticeable drag can be felt then nip up the lock nuts while holding screws still from rotating. Then do the inner screws, checking as you go that movement is still free and not binding. The handle should not be hard to turn at any point.

If you get one of the old books on these lathes — my favourite is L H Sparey's "The Amateur's Lathe" — it will explain a lot more about getting the best out of these old machines.

…or by replacing the gibs entirely with new ones made of brass….

I had to do this on my WM250V-F. The original gib strip was a piece of MS that was off the shop floor methinks.

Original gib strip …

New Brass gib strip… the undercut on the dovetail is obviously too wide but it is a Chinese machine…

George.