[joshuaf]

I've got a weird issue with a homemade 3 axis CNC I'm hoping the group could give me a hand with. I've got two motors powering the Y axis, and once in a while one of the two motors will stop responding. The step drive controlling the motor will have its error light on. After a quick power cycle everything will work fine. It's happened twice now, the same axis both times. Thoughts?

Gear:

- 4 x G203V
- PMDX-126 Board
- 4 x 85BYGH450A-47-80 Stepper Motors
- Mean Well SE-1000 Power Supply

Follow up question:

Is there anyway to have it stop the machine in this case? It keeps running. One side of the gantry moving, the other stationary! :O

I've included a picture of the CNC for the curious and a not so great wiring picture.

[morestuff]

Unfortunately the G203V does not present an electrical signal
to indicate the error condition, so stopping the control system
in response to an error will be difficult. Possible work around
ideas include:

1) a mechanical sensor of some kind to indicate that the gantry
is being stressed

2) a photocell taped to the case of the G203Vs to "look" at the
error LEDs

3) modification of the G203V itself to bring out a wire with the
desired signal


The G203V manual lists 4 reasons for the Error light to come on:

1) briefly during power on reset
2) while Disable input is active
3) a short of one of the motor leads, even momentary
4) over temperature

I assume that we can rule out items 1 and 2 so we need
to try to distinguish between 3 and 4. Condition 3 is
expected to latch and remain until power is cycled.
Condition 4 is described in the manual as self resetting
once the drive cools. I would recommend trying to check
to see if this happens when you get an error. Of course
you will need to have a way to stop the machine safely
without removing power from the motors. If you activate
the E-Stop input to the PMDX-126 without killing power,
the PMDX-126 will block the step pulses going to the
motor drivers.

Regards,
Steve Stallings
PMDX

[joshuaf]

Thanks for the response! I read the manual today too and came to the same conclusions. I actually moved the failing step drive to another motor. After a few test cuts I was able to replicate the problem and it happened on the new axis. This leads me to believe the step driver is faulty or extremely sensitive to overheating (was failing after 10 minutes of minimal use). Seems unlikely the short moved with the driver. I'll see if I can have Gecko replace it.