Hello Christian,

> I don't know why it was not possible to reach precisely th factor 50.
Each trials gave me either 48 or 52. Is it normal ??

This is normal. The number of full steps of the motor is always a
multiple of 4.

You can multiply the M1_FS/R parameter by _any_ factor and divide the
M1_gear parameter by the same factor. This procedure doesn't change the
tracking speed. It's not necessary that this factor is an integer.

Michael