Where to get 20 tooth sprockets for plaction wheels

Does anyone know where I can find 20 tooth sprockets that will fit on Andymark's 4 inch plaction wheels? I've looked for a while, but haven't found anything.

Thanks!

EDIT: It's #35

[MrForbes]

I think you'll run into a problem with the chain contacting the hub, if you try to use that small of a sprocket. 22 is about as small as you can go, isn't it?

Originally Posted by squirrel

I think you'll run into a problem with the chain contacting the hub, if you try to use that small of a sprocket. 22 is about as small as you can go, isn't it?

Really? Huh. That limits us a bit. Now the only other option is either more gearing down through sprockets, or getting a double sprocket larger than 15 teeth.

[farmersvilleRob]

You could go ahead and use Mcmaster here: http://www.mcmaster.com/#roller-chain-sprockets/=fu73t2

You could take their CAD drawings and just edit the bore to fit your needs? sounds solid cuz they already have all the sprocket part done correctly and just export it to a machine shop

[MrForbes]

It's kind of difficult to drill the standard robot 6 hole pattern into sprockets like that. Using sprockets from AndyMark or VexPro sure is handy.

[farmersvilleRob]

Originally Posted by squirrel

It's kind of difficult to drill the standard robot 6 hole pattern into sprockets like that. Using sprockets from AndyMark or VexPro sure is handy.

Yeah your right, but what do you think about having a machine shop making one? Just asking cuz we were hoping to do that, but is it possible? :/

Originally Posted by squirrel

It's kind of difficult to drill the standard robot 6 hole pattern into sprockets like that. Using sprockets from AndyMark or VexPro sure is handy.

Would it be viable to add an extra stage of gearing to the wheels? Like another stage between the gearbox and the wheels?

[MrForbes]

What are you trying to do? make the robot go faster?

Originally Posted by squirrel

What are you trying to do? make the robot go faster?

We are at 10.05 fps, and want to go around 12 fps.

[MrForbes]

And you can't find a larger sprocket for the transmission?

Originally Posted by squirrel

And you can't find a larger sprocket for the transmission?

We're using CIMple boxes, so that's 12 tooth pinion gears on CIMs going to a 56 tooth output gear which runs a 15 tooth double sprocket, going to "x" tooth sprockets on the wheels, where "x" currently is 22 or 24.

We can't change the gearbox itself, so we either need a larger double sprocket to mount on the CIMple box output shaft, or smaller sprockets to go on the 4" AM plaction wheels.

[MrForbes]

And you're stuck on using 4" wheels?

[PAR_WIG1350]

Originally Posted by SuperNerd256

Really? Huh. That limits us a bit. Now the only other option is either more gearing down through sprockets, or getting a double sprocket larger than 15 teeth.

or you could find 2 half inch bore sprockets with a key way (you could add that if you really had to) thin enough so that 2 would fit on the output shaft back to back.

Originally Posted by squirrel

And you're stuck on using 4" wheels?

Yes.

Originally Posted by PAR_WIG1350

or you could find 2 half inch bore sprockets with a key way (you could add that if you really had to) thin enough so that 2 would fit on the output shaft back to back.

Hmm. That... Could work.