Need Help!- servo z dac underflow

[tonymann]

i have a EZTRAK series 1 machine that I inherited from my expartner. I have used it for 5 years very light machining. Now it runs and randomly it gives the "servo z dac underflow". I thought it was a bad connection to the control board but after checking that I get the same message but not at the same time in the run. Any ideas?

[machintek]

2 or 3 axis machine?
if 3 is the Z ballscrew on the left side of the head or in front? Does the Z motor have 1 or 2 cables coming out of it.
A overflow occurs when a move is commanded but not seen.
A underflow occurs when a move is not expected and seen.

George

[tonymann]

George

It's a 3 axis, they added the Z axis onto the machine. The ball screw is in the front of the head. The Z motor has 1 large cable going to it. The error mesage is servo z dac underflow. I have cleaned out everything and the Z axis works great when I jog it. When the program is running all of a sudden I get this error. I start the program over and it keeps getting the same error but not in the same part of the run.

Tony

[machintek]

Bridgeport had a recall of the Z axis motor on the EZTRAK. It seems that the linear scale would miscount due to cutting vibration causing the control to make corrections uncalled for sometimes with dire consequences. So they required all EZTRAKS with Z axis to be equipped with motors with rotary encoders thus the reason I asked about the 2nd cable.
Anyway, if your Z scale sees a count it did not command, it will give this error.

George

[cidteach]

im getting a z dac underflow error from my machine, i've played with the limit switch at the head/face ballscrew. seemed to work ok for one short run and then it konked out again, over and underflow errors seem to just pop up.
i have 2 cables coming from the z drive motor. all connections are solid and clean.

any clues guys?