Hi, thanks very much for this tutorial – extremely helpful. I’m designing a final arm segment joint (the one that rotates the end effector) to be implemented with an RC style servo which allows attachment of a C clamp across the servo body (as you recommended here: Building robotic arm with servos, attaching joints to horn?). The arm segment will be ~20cm long, < 600g total with center of mass ~3/4 towards the end effector. No loads. It will sweep back and forth in the x-y (horizontal) plane.
What I’m concerned about is the downward z-axis force/torque due to gravity putting extra wear on the servo.
Is there any rough rule of thumb that says if you spec a servo with torque rating equal to say double (or 5x, or ?) the torque that would be required to rotate/lift the arm in the z-plane, that it should be robust enough to withstand this perpendicular force without significantly impacting its service life? Thanks!