1B: Power Transmissions
Shafts and Bearings
Shafts
Shafts transmit rotational power along an axis, with hex shafts being the most common in FRC. These hexagonal shafts, typically in 1/2" and 3/8" diameters (measured from flat to flat), may sometimes have rounded corners, known as "rounded hex" or "Thunderhex."
Bearings
Bearings allow shafts to spin independently of plates and/or things to spin independently of shafts. Standard hex shafts use 1/2" hex bearings, while rounded hex shafts can use round bearings for easier assembly.
Example
Example of a Shaft Spinning in a Bearing
Bushings
Bushings are a cheap and low friction alternative to bearings and are used with metal shafts such as shoulder bolts, hex shafts, and round tube, mainly to save space. They are made out of a self-lubricating material such as bronze or acetal/delrin and typically used in applications with relatively low RPM, such as for pivots and linkage joints.
Modeling
The easiest and most parametric way to model shafts is to use the Shaft
Featurescript, which you learn how to use in the following exercises.
For bearings, insert your desired bearing from the MKCad app.