What can I get away with in bearings?
December 1, 2011
I'm in the process of building up a drive system from scratch around a couple of high-torque NEMA 17 steppers. The idea was to use a small V-Belt drive to provide a boost in torque so I could use larger wheels and get up off the floor a bit. I have a 4:1 reduction going with an intermediate pully in addion to the drive and wheel pulleys. I'm machining all the parts myself and have the pulleys made. I wanted the ends of the wheel and intermeadiate pulley to hang free. Looking at bearings it's become clear that even cheap ones if doubled up on the fixed end of each shaft are going to add up to a lot of cost.
Can I get away with simple *single* radial ball bearings on each shaft in a lightly loaded drive system like this? The weight would not be more than a few Lbs. It's not going to be giving my kid piggy back rides or anything. I've selected LiPo batteries to get lots of juice for the steppers at a low weight. I anticipate the total weght would not exceed 6 - 8Lbs in the end. I know that I can keep the loads on the pulleys light by not pulling the belt super tight. The steppers would stall long before the belt slipped. I just don't want to make a bearing eating machine in addition to a normal money eating robot.
Keeping it to a single bearing bored hole also keeps the complexity of the bracket to hold the whole thing down.