When stepping through the “Using the Printer, 002 - Connecting The Printer” procedures, and in “Manual Control” (using K8200 Repetier-Host V0.95F) and sending a command for the Z-Axis motor to move up 10mm: the response is erratic. On some occasions the Z-Axis motor will send the bar up. On other occasions the Z-Axis motor will send the bar down. Other times the motor “hums” and does not move the bar in either direction. I can give it a manual twist and it will start rotation sometimes. Other times the motor advances in either direction only part way. I have tried increasing the stepper motor voltage to approx. 0.55V in small increments with no avail. It seams as though the command from the K8200 board to the stepper motor is corrupted? Any suggestions?
The stepper voltage would be the most likely cause, but you’ve (mostly) already addressed that. You could go a bit higher with the control voltage, at least to see if that helps. The driver should be able to tolerate as much as 0.60 - 0.65v for a short test.
This could be a loose wire to the motor. Make sure the pins are firmly seated in the molex connector housing. They can sometimes pop loose when the motor is being connected.
You can also try swapping the Z motor connector with either the X or Y axis. See if the Z motor can be driven by either the X or Y output, and also test whether X or Y can be driven by the Z output. This will determine whether the problem is in the motor wiring or on the controller board.
If the problem is on the controller board, you can swap the motor driver daughterboard for the Z axis with either X or Y to see if the problem follows the stepper driver card.
You should also check the nuts at the top of the threaded shaft.
Make sure they are not to tight and the shaft turns without a lot of binding.
Disassembly of the Z-Axis Motor cabling has begun. Man do I dislike cutting through shrink tubing.