Loose Nut

A few of those inexpensive import XY tables have been noted to have inconsistently lead screws.

That is not a deal breaker. Just use a mag base and your dial indicator for positioning.

The only critical dimension is the distance from the mounting surface to the center of the leadscrew . If I do this right I'll be using the Z axis DRO readout to set that dimension . If I mess it up , I have enough aluminum to make it over ...

I know bronze is expensive, but it might make a better long term quality replacement. Maybe even brass if you add an oil line. Its an import mill, but it will still cost a few thousand dollars (minimum) to buy a new machine. Why not improve what you have. If backlash is your concern you might also play with the idea of a split nut you can adjust.

Every manual machine I have played with has some backlash. I bet with a split nut (if the screw is good enough) you could get it down under a thousandth. Certainly under 5 thousandths. If the screw is badly worn you may have to adjust it at the ends and accept some more backlash in the middle.

A split nut (the ones I have seen) is split down one side with three screws both holding it together and pushing it apart. When the nut wears you just loosen them up, pull it together some more, and then snug up the screw/s that push it apart. The little Taig mill was that way. If I was willing to to accept low speed and acceleration (it was CNC) I could adjust it to better than .001 backlash. It just had high precision

To increase the life of your nut you might also run a simple oil line to it so you can give it a shot of oil to lube it and flush the dust out once in a while.

One caveat. I think they leave a lot of things loose on a a lot of import machines because alignment isn't great. If you get everything tight, you may need to add some adjust-ability for alignment purposes to prevent binding. Maybe just slotting or wallowing out the holes that mount the lead screw bearing blocks.

Wow! Listen to my arrogant ass acting like an expert. LOL. I am just making suggestions. Only you know what is best for you.

Oh, yeah. Some of your backlash may be coming form the lead screw bearings. In better CNC machines they mitigate that with back to back angular contact bearings machined as a pair that when tightened together take out virtually all of the slop in the bearings. It can be done with v-groove bearings and a shim or spacer. That's typically a lot cheaper, but maybe not the same ease and longevity.

This machine has split nuts ... The X nut has the adjustment bottomed out . I could make one out of bronze casting stock I have on hand , but I think the delrin nut with 3 times the threaded length will last longer . I never really noticed excessive - in my opinion - backlash until after I added the power feed 4 or 5 years ago . I have eliminated 99% of the bearing backlash with the design of the extension I had to make to adapt the power feed unit . I'm not too surprised with this happening , I've had this machine for like 25 years and it's made a LOT of parts .