[gus]

TNC410
So at the end of a part when it should be a z rapid up the machine quits. On restart z axis will not home flashing error movement error A

Lights on axis drive[Siemens] are all fine

changed parameters to home z last, other axis home fine. swapped the z axis brake relay as a wild guess with no effect.

control counts a few thou if you slow it down when it tries to home, but have not confirmed it is actually moving .

There do not appear to be any fuses etc after the drive per the wiring diagram, so I guess it is time to pull the motor off of the top

I have another machine just like it but with extended z travel, I could swap the motor, but it has work to do too....

Ideas?

[webstooge]

Movement monitoring error in %.2s
Cause of error
The axis is moving at least 4 times slower or faster than commanded by the nominal speed command output. - Large backlash (ball screw, gear, belt, coupling, etc.) - Tool is worn - Excessive machining feed rate - Spindle speed too low - Insufficient lubrication - Mechanical stiffness - Machine vibration - Analog axes: Excessive drift - Analog axes: Defective tachometer - Analog axes: Defective carbon brushes
Corrective action
- Check machine parameter 1140.x - Remove any large backlash - Replace the worn tool - Check the lubrication - Remove mechanical stiffness - Analog axes: Adjust the drift - Analog axes: Replace the carbon brushes of the tachometer, adjust the tachometer - Analog axes: Replace the carbon brushes of the motor

[kongzai]

Check Z servo lag. Allow the machine ready, but don't pass reference yet. Using MOD key, change position display to display "LAG". You will see all 3 axis servo lag, with normal range not exceeding +/- 0.002.

If this is the problem, turn the "Drift" potentiometer on the Z Siemen drive to correct it.

[gus]

LAG tells me what I expect, that it gets to .005 or so and GPE's

Removed motor from axis, from feel it appears the brake disengages when the machine is enabled. IOW, hard locked when emo'ed, spongy[fighting the electronics] when enabled.

Would not expect a minor drift to affect homing at a crawl.

This machine has run almost daily for 3 years, so it is not an unfamiliar machine.

[gus]

Well, no luck so far, may have to break down and swap a motor off of the other machine altho deathly afraid of blowing up 2 machines....

[crispy-duck]

We have a similar intermittent problem on our CNC (Correa FP30 Haidenhain 426 controller).... Have tried swapping cables on the servo drives, but problem then moves from the Z axis to the Y axis!!!! Which kind of rules out many options.. Did you sort your problem out, if you did how????

[gus]

It ended up being the motor, even tho the motor homed on a different machine, sapping that machines motor onto it and it works fine now.

[crispy-duck]

My problem now sorted. Had to replace two siemens servo drives before problem went away. Machine has been running fine for the last three days.