Hi! To prepare for the 2020 season, my team decided to build a swerve drivetrain. We are a relatively new and inexperienced team, so we modified the WCP SS swerve modules(the old version without falcons) instead of designing new modules from scratch. Thanks a lot to 1323, WCP and 2910 for making this project possible!
Here are the main modifications to the module that we made to simplify the project:
-Azimuth bearing changed to SA035 X contact bearing because they are easier to source in China and are also possibly more suited to take moment loads than radial bearings
-modification of main azimuth gear and plates to accommodate SA035 bearing. After modifying the azimuth gear, we actually had to have a machine shop mill the gears from 7075 round stock instead of from vexpro gears.
-redesigning shafts so that they could be machined from vexpro hex stock. This made machining easier, but also meant much more backlash as the hex no longer is oversized. To deal with this, we added retaining compound to fill in the gaps.
-We didn’t want to directly make the leap to treaded billet wheels. And so, we changed the wheel to 4’’ Hi-Grip which is cheap and simple. However, this change led to most of the redesigns. We had to change the large bevel to fit the 1.875’’ bolt pattern, and also make the wheel forks, small bevel, and spacers accommodate this change.
-When the machining of aluminum wheel forks messed up, we designed new forks optimized for printing and made them in-house to save time. Astonishingly, the printed forks seemed to be more rigid.
-Changed azimuth encoder to direct 1:1 after building the first module to increase accuracy. We were happy to find out a few weeks later that the newest WCP falcon swerve has the exact same change!
After completing the first module, we attached it to a recycled practice bot frame along with three caster wheels. It looked pretty messy and could only strafe while spinning uncontrollably.
When the second module got assembled too, we built a new frame out of extrusion and attached both modules, allowing full swerve motion. We plan to get two more modules completed and also build an everybot on top of the swerve to test scoring before kickoff.
We are still very new to both swerve and FRC, and unsure whether the decisions we made in this project are sound, so we’d love to get as much advice as possible!
This would be a summer 2020 project if anything. But yeah, the idea would be to use 3DP parts for both the fork, the azimuth pulleys, and the encoder mount. The only machined parts would be a CNC aluminum base plate, and a laser cut plastic top plate. The design also uses a minimum amount of gears, bearings, shafts, and other hardware. I think $200 (USD) can be achieved.
