Because F=12,5N, I calculated it to mass (12,5N/9,81) and thought the max mass was 1,27kg.
But, I guess I overlooked the inertia.
The motor I start from, is this one: http://www.eminebea.com/content/html/en/motor_list/pm_motor/pm35s048.shtml
The motor has to rotate 1,25 rotations per minute (1...