Backlash no more!!!

It's been several days now since I applied Loctite 638 to the yoke where it connects to the quill. It took me weeks or more to figure out the fairly obvious conclusion that the backlash exists between them. And I was even able to just make it out by eye with the fixing bolts removed. Anyway, after all that, the acid test is whether or not the backlash has gone. I was seeing as much as 120um (0.12mm - or 5 thous in old money), which really isn't very good at all, not least when you find that the ballscrew / ballnut has almost zero wear and backlash itself.

I'm all hot and cold and sore all over as a result of a nasty virus that crept up on me yesterday afternoon. I ended up going to bed around 9pm but it's clearly not going to be a 24h bug. But it's driving me round the bend not being able to do anything. And I'm dying to find out if the backlash has gone.

This is measured with a mag base mounted on the quill nose and a DTI touching the yoke next to the ballnut, like this: 

Bingo!! The hysteresis / backlash has pretty much vanished now. I can see perhaps 25-30um of backlash-like movement between the yoke and the nose of the quill. That's the very worst case I could see over most of the rage of movement using my Mitutoyo 10um/div DTI. In most places it's closer to 15um but even 25um is 0.001", which wouldn't be so bad. Although this wasn't an exercise in metrology, it's got to be pretty close to the reality.

As mentioned above, I would expect the quill to ease up with use, so the backlash (hysteresis) and spring (elastic) element should improve. To some extent, I suspect the backlash is dependent on the loads acting.