Dual 608's:
Right now the arms use dual 608's at the pivots. That's going to spread some of the forces out over more plastic. It also will constrain the shaft through the 608's quite well.
An alternative would be to mate the shaft tightly with one 608 and use a material like aluminum to mount the outside of the bearing. The aluminum isn't going to let the bearing go anywhere. The tightened down shaft won't go anywhere inside the bearing. The bearing isn't perfect trying to do this (single row of balls).
How much do you loose going to one bearing in this case?
I'm not really after a 0.00327" sort of answer. "A lot", "not much" and "don't do that" are all a lot better than what I have now. My concern is mainly making the arms more massive than they need to be. Cost is not really to crazy either way, but it's lower for the simpler arm.
Right now the arms use dual 608's at the pivots. That's going to spread some of the forces out over more plastic. It also will constrain the shaft through the 608's quite well.
An alternative would be to mate the shaft tightly with one 608 and use a material like aluminum to mount the outside of the bearing. The aluminum isn't going to let the bearing go anywhere. The tightened down shaft won't go anywhere inside the bearing. The bearing isn't perfect trying to do this (single row of balls).
How much do you loose going to one bearing in this case?
I'm not really after a 0.00327" sort of answer. "A lot", "not much" and "don't do that" are all a lot better than what I have now. My concern is mainly making the arms more massive than they need to be. Cost is not really to crazy either way, but it's lower for the simpler arm.