Problem- bridgeport ser2 int4 x axis runaway

[Russell F]

Have a Bridgeport series 2 interact 4 mill, machine had lost paramaters from sitting idle. I installed new batteries and reloaded the params. Machine would power and home on y and z but would throw a 'gross positioning error A' on the x axis when it started homing. I changed MP54 (acceleration param) to a lower value and now it will home on all three axis. Now the problem is when i get the homing complete and get to the manual screen the X axis starts to move on it's own and throws a 'gross positioning error D'. The param sheet i used is a copy i took out of the machine several years ago so I'm pretty sure they are right. I swapped the X and Y axis drives and the problem stayed with the X axis. I also checked the tach wiring on the X, and it seemed fine. Any ideas?

Thanks

[machintek]

I would swap the x and y motors first. It is rare that the Bosch drives go bad.
According to Bridgeport, the SEM motors need to be looked at every 4000 hours of operation. I admit that most go way past that figure before needing attention.

George

[gus]

the accel parameter 'should' be meaningless while homing. the control just puts out 'x.x' volts [according to parameter] until it sees the trip dog. then it looks for the marker pulse. once it sees the marker pulse then it tries to close the loop.

does it actually settle after homing or is it running away as soon as it tries to lock up the servo? that may indicate a counting direction /axis direction parameter misentered

As soon as it tries to lock up the loop, it is telling it to go the opposite direction and boom GPE.

If it will actually finish homing but not move correctly afterward, perhaps the max feedrate parameter was changed and now with the new[old] number the servo is no longer tweeked correctly. in that case it ought to function at some level with the feedrate override turned down a bit.

[kongzai]

i suggest you to bypass the zero return progress, by modifying machine parameter, possibly MP1340. This is for the ease of testing the axis motor without doing a homing. Swap the motors cables so that Y servo controls X motor. You will be able to confirm whether it is a cable or motor fault.