Trying to build a case for a belt driven ball screw axis versus a Planetary gear box, with the fact that the motor vibration would carry down the gearbox to the axis, but the timing belt drive would isolate the motor vibration. How would I model this? and ideally a way to get a factor of difference of performance. if the belt does act like a spring, how would I figure out its stiffness? Any help appreciated. Thank you.