[Gnome]

I have a significant amount of backlash (1-2 thou) on the x-axis of my bridgeport cnc mill. I have placed a dial indicator on the end of the ballscrew to verify that the lost motion is not coming from the A/C bearings and also checked the gibs per the bridgeport manual. The ballscrew is a single nut, precision ground 32mm dia screw (actually originally installed by bridgeport and not a retrofit assembly).

I believe that i have limited the backlash to the screw itself but i find it interesting that the wear seems to be only from the center of the table to the extents on the right travel limit of the table. The left 1/3 of the ballscrew travel still feels tight with very little backlash. I assume that the previous owner must have machined only on this side of the table or is it possible that the screw is not properly aligned to the table and guideway?

I also wonder how this could be fixed. I have read about oversizing balls on single nut screws but won't this cause the nut to bind on the left side of the travel if i was to eliminate all the lash on the right side. I know that i can get the nut and screw reground but i am wondering if anyone else has any thoughts. I suppose i could also just run my vise on the left side until it is similar in wear to the right and then use oversize balls... seems like a crappy solution though...

[Gnome]

Bump... Anybody?