[Bob La Londe]

Backlash on Z. I seemed to have measured some backlash on Z in the last few months. When I first started actually cutting jobs on the mill I noticed that the Z sounded a little noisy, but I had very little backlash. Maybe a tenth or so. (I thought) In the last couple weeks I have noticed maybe 7-8 tenths backlash when I use the tool setter and jog .001 at a time to zero my tools. I know the machine spec is only 0 to +.003, but I always figured that was as much to do with the electronics and following error as anything.

I pulled the front and top cover to look at things. The little rollers are rolling like they should, so I don't think its racking. The spline shaft is greased. The ball screw is getting oil. Is it just old? Or did I just not notice the backlash before?

When I bump the Z back and forth by .001 I can see the ballscrew turn the same amount for one or multiple bumps so its not following error or drive lash going into the screw.

[Bob La Londe]

Is this normal? Is there an adjustment I can make?

[Bob La Londe]

I was hoping somebody could help with some guidance in isolating the cause of the backlash, so I could decide if it would be worth trying to reduce or not. Anybody? Please? 7 tenths is not huge but it is noticeable. Every time I touch off a tool with the height setter. For 99% of what I do +/- .001 is more than adequate. But occasionally I make parts for other machines and it would be nice to know my variances are mostly from cutter size and deflection.