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

Re: Load and Friction
 

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

Re: Load and Friction
 

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.

Re: Load and Friction
 

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

Re: Load and Friction
 

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

Re: Load and Friction
 

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.

Re: Load and Friction
 

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...ductId=4483496

for example

Re: Load and Friction
 

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.

Re: Load and Friction
 

New catch-phrase

Re: Load and Friction
 

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

http://www.vexrobotics.com/spacers.html