Bed does not find Z-axis home position anymore

[JWvdWiel 0]

Below problem occured when I started a print after just having finished one succesfully.

When I use 'Auto Home' the bed goes up to the nozzle (in the front-left horizontal home position), but it does not stop anymore. It tries to go 'through' its home position, bending the bed. It looks like it misses some kind of end-signal. How is the 'home trigger'? Is there an end-switch that maybe fails? Or is it a software issue?

Thanks for advice

[Nicolinux 287]

Hi,

and welcome to the forum.

When does the bed not stop any more? When it goes up or when it goes down?

When you first start a print, the bed tries to go down first. There it hits the limit switch - it does a kind of bounce movement, first triggering the limit switch and then going a bit up and down again. Then it waits for the nozzle to heat up. After that, it goes up and stops a few cm before the nozzle. There it waits until the nozzle starts extruding some filament and then the print starts and the bed goes all the way up to the nozzle.

Where does it exactly fail?

If it is the first - when it goes down, then most likely the mechanical limit switch at the bottom might be dislocated or the switch's arm bent so the screw underneath the bed does not touch it when it reaches the bottom.

When it is at the top and the bed tries to go higher, then you might have flashed the wrong firmware. If you have an Ultimaker 2 and would flash the Ultimaker 2 Extended firmware, then the printer thinks it is taller, and would try to move the bed further up.