well I guess you are right. I've calculated my steps per mm to 100, but in fact, it should be 80. And that's exactly the factor from 50 to 62.5.
I somehow managed to get the bed leveled correctly, and the axes too, depite the wrong steps/mm. And that was it what kept me from thinking the steps could be wrong...the horizontal dimensions were right. I've printed a fan cover for a 120mm fan which came out pretty nice and fitting (it was only 10mm in height, so the error didn't make much difference), and i've printed lots of vases and stuff, where the height-dimensions aren't critical ;-).
So, back to calibrating, now with the right steps per mm, and many thanks for the idea.
I somehow managed to get the bed leveled correctly, and the axes too, depite the wrong steps/mm. And that was it what kept me from thinking the steps could be wrong...the horizontal dimensions were right. I've printed a fan cover for a 120mm fan which came out pretty nice and fitting (it was only 10mm in height, so the error didn't make much difference), and i've printed lots of vases and stuff, where the height-dimensions aren't critical ;-).
So, back to calibrating, now with the right steps per mm, and many thanks for the idea.