Z Axis Homing (no replies)

Hello,

I have now finished building my Mendel90 and even made my first print.
But somehow the Z axis doesn't always do what I want.
After every print it stops at the bed and thinks it is at Z:175.2, even though the position is 0.
175.2 is the position where its homepoint is.
What am I doing wrong and can someone please help me?

Thank you very much.

PS:
I am using RAMPS 1.4