Serious thoughts on DRO or new screws x and y Series 1 variable 2hp

[expressline99]

Another way to determine the source of backlash is to measure the backlash at the center of travel and to measure it at either extreme of travel. There should have been very little chance of wear a the extremes of the lead screw so the measured lash can be assumed to be due to the lead screw nut. The difference between the backlash at the center and the extremes will be the wear on the lead screw. My old mill has a difference of about .004" showing that most of the wear is in the nut.

To measure backlash accurately, the gibs should be loosened to eliminate drag. I would mount a test indicator on the quill and clamp a block to the table and measure the position coming from either direction to reach a particular dial setting. The difference will be your backlash at that position. The reason for loosening the gibs is that tight gibs requires more force to move the which creates lost motion due to flexing of the frame, torquing of the lead screw, etc.

The backlash is .010 difference from the center to the outside after the nut is tightened the entire way. .045 in the center .035 outside edges. At that are you thinking it's the nut or screw? I am still going to take it completely apart. The saddle gib won't tighten enough to keep the table from twisting by hand.

I was using the machine tonight making a t-nut for my qctp...I didn't finish it because I'm working on horrible learning curve with a machine that moves in the wrong directions. However, even as bad as it is the single dimension I finished came out within .002 of what I was shooting for so not terrible. The machine needs leveled...head needs trammed.. table mechanisms fixed.

The wear on the saddle ways bothers me. I hope that twist is only from a worn out gib. Otherwise, that knee and saddle...and table might go out for grinding.

Paul