Center to Center with belts

[DampRobot]

Originally Posted by MetalJacket

Just to clarify for my own knowledge, there should be little to no performance issues using 9mm wide belts compared to using 15mm wide belts (like those in this year's KoP) assuming they both have the same tooth profile? I'm currently working on a practice sheet metal chassis using belts and I'm trying to make the wheel wells as thin as possible but I don't want to compromise performance for space. Thanks,
Jesse

Not necessarily true. The maximum torque that can be put on a belt varies proportionally to its width. If you're right on the edge in terms of how much torque that can be on the belt, the switch from 15mm to 9mm definitely makes a difference in whether it will ratchet or not. If you want to be sure, check the Gates website. They should have some nice tables that give all of the relevant torque and speed information.

Just keep in mind that for FRC, your FoS or duty rating will probably be much lower than 1 (i.e., it can take more torque than what's on the table). Those belts are designed for hundreds of thousands of cycles, something they'll never see in FRC, so we can probably get away with more torque than they were designed for. Adam Heard probably has a more exact number, as he's built a lot of belts drivetrains before.

[MetalJacket]

Originally Posted by DampRobot

Not necessarily true. The maximum torque that can be put on a belt varies proportionally to its width. If you're right on the edge in terms of how much torque that can be on the belt, the switch from 15mm to 9mm definitely makes a difference in whether it will ratchet or not. If you want to be sure, check the Gates website. They should have some nice tables that give all of the relevant torque and speed information.

Just keep in mind that for FRC, your FoS or duty rating will probably be much lower than 1 (i.e., it can take more torque than what's on the table). Those belts are designed for hundreds of thousands of cycles, something they'll never see in FRC, so we can probably get away with more torque than they were designed for. Adam Heard probably has a more exact number, as he's built a lot of belts drivetrains before.

OK thanks, I'll check out the Gates website to try to get some more exact numbers.

[jspatz1]

We've always had perfect results by simply laying out the belt in a CAD sketch. Draw the pitch diameter circles of your pulleys, connect them with tangent lines, trim the inner portion of the circles, then measure the loop length. Adjust the C to C until the loop length matches the available belt pitch length.

[chmorroni]

We haven't tried to do the C-C in our CAD until this year, but I am going to use this calculator to do it. It should get you pretty close, if not dead on a good tension. If it isn't exactly how you want it, you should be able to make small tension changes if you are using COTS gearboxes.