Z-Axis sometimes turns the wrong way with auto home

Hello evreybody!

I have the following problem with my K8400.

When I auto home the X and Y axis move fine and do what they have to do.
The Z axis however sometimes just turns the wrong way and the bed goes down instead of up.
Also in moving the axis via the menu the motor irradicly moves by going up and down really fast when I move the wheel.

What have I already done?

  • re-installed firmware.
  • swapped motors.
  • swapped drivers ( voltage check om all were good to)

What could it be?

Thanks in advance.


Check the end stop for the Z axis make sure the cables are seated on the end stop and the board.
Make sure the end stop is clean.
When you updated the firmware did you use Arduino software 1.0.6 or below?
If not you can find it in this link.

I cleaned the end stop and checked the wires.

I used arduino 1.0.6 to load the firmware.

Problem is still there.

Try swapping the end stop (move it) from the Z axis to the X or Y to see if the problem moves.

Will swap the end stops this weekend to see if it will help. Will report back here after that.