Load and Friction

Hello!
we’re planning on using a vexpro double sprocket 1/2id round for pulling our lift(about 80lbs max load), can I just make it an idle sprocket with the vexpro tube stock+1/4 bolt, or do I need some bearings for the friction?

Paul

How do you intend to pull up your lift with an idle sprocket?

You could do either. You might even be able to use an igus bushing, if you can figure out something the right size.

If you don’t use a bearing, you probably want to use some grease on the bolt.

The elevator is powered from a sprocket on the bottom of the lift, top is the idle one.

Igus bag only have 1/2id ones, maybe a bronze bushing?

You can do anything with enough torque, but short answer is I would recommend at least a press in brass or plastic bushing (cheap, and available from McMaster-Carr).

You could do the math to find out exactly what difference in friction there will be on the sprocket shaft, but I would worry more about wear. The sprockets you buy from AndyMark or Vex are made from aluminum. Aluminum does NOT wear well, even when anodized - a few hundred turns under load and I would expect it to seize on the shaft.

I would also look at the hardware store, for a bronze or nylon bushing, they might have something that will fit.

http://www.lowes.com/pd_446416-37672-58075_4294710799__?productId=4483496

for example

To make the idler sprockets on our lift it took a little tinkering. We used a vex plate sprocket on a flanged bearing. Then we made spacers our of 3/16" aluminum by cutting a circle with a 2" or so hole saw, and then cut a 1-1/8" hole in the center of that. Those spacers took up the extra space on the surface of the bearing so that we could use a washer with 1/2"id and a clamping shaft collar to hold it all together. It just makes a sandwich of washers basically that allows the sprocket to be forced to stay in place but can still spin freely on the bearing.

New catch-phrase

Vex’s nylon spacers? dril it out to 1/4 or 3/8?