I have never fooled around with the ball nut. Anytime it is too loose, the ballscrew gets regound and bigger balls are loaded. I installed a few machines at a place called National Precision in Franklin, TN. That is his business. He rebuilds ball screws.
To adjust backlash, I increase the value in the machine by .002 inches. I then machine a circle in aluminum with a spring cut. Now sweep the circle with a dial indicator. The steps you measure are how much it is overcomped. Subtract this value from what is in the machine. If it varies at 3 and 9 oclock, then your X ball screw is worn unevenly. You may want to average the compensation. Ditto for the Y.
To get to the backlash value, at the main screen, press the * key, the key word is 11235 followed by enter twice. Do not forget to save. If a ball screw is replaced or reground, the existing pitch error comp values are worthless.
George |