This year I want to try making my drive base extremely frictionless. My first idea was to put ball bearings on all of the screws that held my wheels in place. Before I commit to this design, I wanted to come to the forums and ask if anyone tried this in spin-up. If you did try this, what were the benefits and downsides?
I would recommend to just use normal bearing flats. Ball bearings are better for catapults or arms.
We put them on our drive motor axles and used screw joints on our wheels and geared them together. We had no problems and used the same drive base all year and it still drove straight with little friction at worlds.
But we were advised by someone from vexu it was an unnecessary weight increase because the screw joints took all the stress so the ball bearings did very little to reduce the friction in our situation.
So if I made a lifting arm I should use them on the joints?
If you want to use ball bearings, use them for a flywheel or fast moving object. Anything that’s slow moving (such as a lifting arm) should just use regular bearings. Ball bearings are heavy, and somewhat expensive. As stated above, they really aren’t worth putting on your drivetrain due to the weight. Teams have achieved very low friction just using good build quality and screw joints.
It would be a very good learning experience to setup a test stand and compare motor loads with bearings vs ball bearings.
Also, to note, ball bearings have increased weight, rotational inertia, and (if you don’t deal with the pre-packed grease) significant friction themselves.
The plastic bearings, with a little dry lubricant (graphite from pencil lead) are a good solution.