[shimstack]

Hi Everyone,

First post here, but I've gained a great deal of knowledge from this forum by searching for help on previous issues. This forum is a wealth of knowledge.

I'm working with a 3-axis Centroid M15 equipped Bridgeport Series II knee mill. It seems to be losing counts on the X-axis between jogging and cnc cycles. For instance, I'll drill a pilot hole by jogging the mill to position (x and y) and plunging the quill to drill. Then if I add a counterbore using a canned circular frame cycle at the same position, the counterbore will be offset by approximately .03" in the -x direction.

I've tried multiple drilled holes in an arbitrary arrangement, and one cnc cycle to counterbore all of them. The results are the same at each location- an offset of ~.03".

I've checked:

1. Encoder counts on X and Y at the PID screen- 8000ct/rev.
2. Lash compensation- measured at .0006 X, .0015 Y, and .0065 Z. The DRO reading is repeatable to my dial indicator to +/- .0002.
3. There are no values entered in the screw comp table

This machine seems to have developed the issue after running tune and drag. Are there PID parameter changes that could lead to this? I've noticed much slower axis accel/decel after running tune and drag. Are counts being lost on axis reversal?

Thank you to anyone who can help me resolve this.

Andy

[shimstack]

Resolved.

The head was knocked out of tram at some point in the recent past (?? #%*!).

I was using a long drill in a chuck, and a short endmill in a collet, so the two feature locations in the part were quite different.