Hi, I was just wondering what defines the maximum lift weight for the robot arms, for example the AL5A can only lift 4oz whereas the AL5D can lift 13oz, as the same mechanical parts are used is it down to the servos capabilities?
Probably, check the torque specs on the servos used.
The stall torque and the length of the segments dictate the arms strength. We designed the arms to be economical. So the smaller arms use cheaper servos. If one where to build as small an arm as possible using the 1/4 scale servos an arm could be made with the most strength.