Re: Team 1671: Off-season belt drive prototype
 

Tiny nitpick: right now the set of timing belts on the closed end is closer to the 1x2, while the set of timing belts on the open is farther from the 1x2. If you make the open side closer to the 1x2, it will increase the area you have for your intake mechanism.

Re: Team 1671: Off-season belt drive prototype
 

haha thanks for catching that. That could really give us some extra room.

Re: Team 1671: Off-season belt drive prototype
 

If you are going to put your belts around a frame member, changing them in the unlikely event of a breakage or the slightly more likely event of a broken tooth would be impossible (welded connection) or at least a pain in the butt (bolted connection).

Since timing belts weigh next to nothing anyhow, if you choose to go this route you may think about leaving a set of spare belts (fastened down out of the way) already around that cross member, just in case you need to swap it out. In this way, changing a damaged belt is as easy as sliding your bearing block, switching the belts, removing (cutting) the damaged belt, and re-tensioning the bearing blocks.

Re: Team 1671: Off-season belt drive prototype
 

Also, what pitch, belt width, and profile are your belts? 5mm pitch, 15mm width, and either HTD or GT2 profiles seem to be the most common belts for FRC drivetrains. You may be able to get away with 9mm belt width, but given the negligible difference in weight I would just go with 15mm.

One other reminder about your choice of pulleys: be careful how small you go. Belts fatigue faster when bending around tight radii in general, and all the design documents I've seen suggest at least 6 teeth in contact with the pulley at all times. An engineer on our team who designs timing belts for a living recommends using at least 2" diameter pulleys for HTD belts (it looks like that's about what you are using). And double flanges on every pulley is a must for FRC (again, looks like you already knew this!).

Great job!

Re: Team 1671: Off-season belt drive prototype
 

I'm really curious about your shaft and bearing setup, would you mind posting a cutaway of that?

If a 6" bumper segment is required, this gain is kind of negated though. In that case I'd run it how he had it to get more electronics space.

Re: Team 1671: Off-season belt drive prototype
 

This may be a terrible idea, but why not run the outer run of your belting inside the tube? With a single cantilevered run and a single internal run, you can fit the assembly entirely within a 2x1 tube, and you could change the belts by pulling the live axle at the end out.

(At least, that's what I'm doing in my theory - not - fact - at - all model)

Re: Team 1671: Off-season belt drive prototype
 

Why run the belts internal?

I've yet to hear a clear advantage to such a setup; and there is a very clear disadvantage (your belts are INSIDE the tube).