Hello! I’m on my team’s CAD team, and I’m in charge of figuring out what belts we should order. We haven’t really used belts much since I’ve been on the team, so I’m concerned about how we are going to put them on.
I’ve been using WCP’s belt calculator to figure what number of teeth belts I should order, but I’m concerned about putting correctly/optimal sized belts on. Do people normally just brute force them on? Is there some conventional way to do it? Are tensioners regularly used? Slots to adjust tension and aid in putting them on? Am I overthinking how hard it will be?
For tensioning we enter the wonderful world of “It depends”.
Are you worried about rpm? If so you can run a relatively loose belt and be fine. Worried about torque/position? Now things need to be properly tensioned.
To tension without additional hardware I would place the driven axle as fixed, with the driving (motor) in slots to tension. I would be careful on how you lay out the slots. One motor mounting screw as a fulcrum and the rest as curved slots is a good way to do this. (See image)
For tensioning, small cams are great. Stick them next to a bearing block and you can adjust the tension just fine. Stick it next to a gearbox, and mount the gearbox in some slots, and you can adjust the tension that way, too.
A couple of examples from CAD (You can browse the CAD here if you want):
Bolt in the top right hole stays fixed, the bottom left is slotted, with the cam helping to push the corner. Should work with pretty much any of the planetary gearboxes out there.
An example without a cam, you can see the holes are slotted for both the gearbox and the bearing block, allowing us to move the motor side to side to adjust the tension properly.
Here’s the bearing block, getting pushed over by the cam. The hole in the tubing just needs to be big enough that the shaft going through it can move side to side enough to let you tension it.
All of these examples were from our 2022 robot. Once built, it’s hard to see the specifics, but I have arrows below pointing to the belt and chains from the example above, all nicely tensioned!
Thank you guys so much for taking time to share your solutions! You have been incredibly helpful to me, these make a lot of sense. I appreciate it so much!!!
