pic: Sprocket legality?

[MattC9]

The gearbox took competition like a boss!(after adding a new reduction stage and a 30t sprocket on top) We had no problems at all! It was a great year!

[lemiant]

I don't understand!!! Is that dynamic tensioning, or does it just keep one level of tension?

[Kevin Sevcik]

Originally Posted by lemiant

I don't understand!!! Is that dynamic tensioning, or does it just keep one level of tension?

With that sprocket, one level of tension. The sprocket will stay in one place as the chain moves, since it's moving the same distance on both sides of the sprocket. To adjust tension, you'd move the sprocket a few links one way or another or swap in a larger sprocket. You could make it dynamically tension by buying or machining an actual floating tensioner. It looks about the same as that, but with a huge hole in the middle that leaves it with rather thin walls. That lets it flex and deform into an egg-shape to make a more dynamic tensioner.

The primary downsides of the floating tensioner are the space required in the chain path and the fact that it's going to reduce the contact angle on both your sprockets. The latter won't matter too much unless you're running a really small (9-12 tooth) sprocket under lots of load, which you really shouldn't be doing anyways.

[PAR_WIG1350]

Originally Posted by Kevin Sevcik

The latter won't matter too much unless you're running a really small (9-12 tooth) sprocket under lots of load, which you really shouldn't be doing anyways.

We've done that. It worked since the load wasn't that bad, until the robot accidentally tried to lift itself using its arm. When that happened, the (steel) sprocket broke into three pieces. To fix it problem a 1/4 in. polycarbonate plate was zip-tied onto the arm so that it would slide off of the pegs rather than catching on them (the added benefit was faster scoring since it was easier to release tubes and turn back for more).