So the Z-Axis stops and stutters when homed or manually jogged. I’ve cleaned the rods and bearings from any dirt etc. I have tried taking the z coupler off the stepper motor to see if it still does it and it does. So I don’t know what could be causing it.
Machine (K8400)
Any Help would be nice.
Thank you,
Dave
Check the Reference voltage for the stepper driver.
You can find the instructions here.
http://manuals.velleman.eu/article.php?id=39
The voltage is fine and I swapped the stepper with one of the other steppers and no change.
Have you tried to re-seat the cables?
Check the pins on the motor and the control board make sure none of them are bent.
I just re-seated the cables and I have checked the pins and everything looks okay. But the machine still does it 
Try swapping the cables on the control board.
Maybe with the X or Y axis to see if the problem moves.
Sorry, didn’t read OP. I have a problem with Z while jogging manually, firmware crashes and reboots.
Hi wrong I had time to swap the cables and no change.
Just a guess.
Is the print head running into the bed?
[quote=“to3dornottobe”]Sorry, didn’t read OP. I have a problem with Z while jogging manually, firmware crashes and reboots.[/quote]That’s a bug in the firmware. If you move the Z axis too quickly the printer crashes.
No haven’t had that yet lol still time for it. so far only the bed stops then stutters 
Last thing that remains untested : the motor. Try plugging another motor to the Z axis and check if you still get the same issue.
You may also want to try swapping the driver card as well
… 
Oops
Thanks Raby.
Ok I think I’m running out of ideas.
The flex connector Z motor to the shaft.
Is it broken?
This can happen if you run the bed all of the way to the bottom without homing it first.
Don’t ask how I know.
Lol
Can you check the settings -> motion menu on the LCD. It could be you have corrupt values in your eeprom.