We are using the Minibot kit we got from the FIRST Choice program and the shaft collars don’t seem to work too well. Any suggestions on something else to use instead of those collars?
Chemi, I don’t understand what the problem about the collars is, they seem to be working fine for all the teams I’ve contacted. Are you tightening them around the flat part of the motor axle?
There are instruction manuals you can download from the Tetrix site. Here’s the link:
http://www.tetrixrobotics.com/Building_System/Downloads/default.aspx?aid=80
Yes they seem to keep moving when we tighten them as tight as we can get them but they seem to keep moving. I’ll get a picture uploaded once I am done at our meeting
Make sure you zoom in =p
We had trouble with our first design that depended on driving torque through the set screws. All of our subsequent iterations have a gear bolted to the wheel so the torque goes through the 4 #6 screws.
There are two axle sizes in Tetrix (at least.) Motor axle is bigger than the other one. To accommodate this there are two different axle hubs. You can’t put the regular hub on the motor, but the motor hub would go onto the other axles but quite loosely. You might not be able to get the set screw on a motor hub to tighten enough on a regular axle. And if you did, the wheel or gear would be off center.
If you are sure you’re using the correct hub and axle combination, take the previous poster’s advice and check to see that the set screw is being tightened onto the flattened part of the axle.
we had one of our sponsers at our meeting last night so i was unable to get a picture but i have another question. Are we allowed to use aluminum round stock on the minibot?
I will have a for sure picture tonight.
Here are the pictures for our minibot. Over night somehow, now the minibot works with no problems.
![P01-27-11_20.06[1].jpg](https://www.chiefdelphi.com/uploads/default/original/3X/a/c/ac617b920e6a273d7d49aef0d484ab371f304833.jpeg)
![P01-27-11_20.06[2].jpg](https://www.chiefdelphi.com/uploads/default/original/3X/9/1/9151193d623f297fc0e588341cbec7a09bc78c85.jpeg)
Instead of using the black set screws, you can always use a 1/4 #6 screw. Our team has never trusted those tiny screws. 
could you be more specific on those screws