Yeah those strengths are based off the stall torques but i'm pretty sure it can lift a robot because it lifted itself. The first time we turned on the arm two people were holding onto the arm and since the programming was screwy some bad things happened. Basically it just thrashed and practicacally pulled out one of our mentors arms. Of course they held onto the arm so the rest of the robot rotated around the main joint throwing the robot off the ground AND FAST! It all happened in under half a second so i'm pretty sure strength won't be a problem ^_^!
As for those driveshafts, i planned it all out to be mounted on seperate shafts to make it easier to work with. One of the builders did that against our planning
Tensioning is a slight problem. We do have a tensioner that slips in but its sort of an add-on not a well thought out thing. It sort of works. Otherwise we just made the chains as close as possible to the needed lengths using offset chains where required. the chains running up the arm have some really cheesy tensioners that i made in about 5 minutes. Velcro on then zip tie lexan forks!
(no bolting, drilling or shedding of aluminum was used in their creation
)