Machine Elements RC Car
This project was a group assignment for our ME338 - Machine Elements Class, which entailed designing and constructing an RC car using the provided motor and electronics. The main objective of the project was to concentrate on the mechanical design of the chassis, steering, and powertrain, rather than the electronics and controls. My role on the team included building the car and contributing to the design process.
Skills - CAD, Solidworks, DFM, DFA, FDM Printing, SLA Printing, Laser Cutting, Tolerancing
Sketches to start
We started the design process by making sketches like the one seen here. These rough sketches were part of the brainstorming process in which we had a brainstorming session for each subassembly and the main assembly. This drawing is for the steering mechanism that controls the car's front wheels.
Final version of the CAD
After we made our sketches and decided the layout and mechanisms, we designed all the components and put them into a SOLIDWORKS assembly. The final assembly includes many changes to the gearbox, iteration 4 of the chassis, iteration 3 of the steering mounts, and the steering bar.
Preparing for crashes
To ensure our RC car could withstand the many crashes it was sure to go through, we did some finite element analysis in SOLIDWORKS. This was done by the FEA subteam in our group, based on sample crash data provided by our professor.
Chassis iterations
The chassis went through 4 3D-printed iterations before reaching the final version. The main changes to the design were, removing the front bumper to improve turn radius, adjusting gearbox spacing to reduce friction, and adding a steering servo mount for better stability.
Steering mounts and wheel hub
The steering mounts went through 3 iterations but the wheel hubs I got right on the first try. The steering mounts supported the forces exerted on the front 2 wheels and also rotated when steering. We increased the thickness to increase strength and used fillets to reduce friction when turning.
The wheel hubs were designed to be press fit into the wheels and I designed a feature for a set screw to clamp onto the axle. The hubs were SLA printed with tough resin so the set screw hole could be tapped.
Working, but could improve
This is the final fully assembled car that we raced with and submitted for our final grade. The car runs and turns as expected, but we overlooked impacts directly on the front wheels. The front wheel bearings were press fit into the steering mounts and they can fall out if the front wheels are hit with an impact. We could have fixed this very easily but didn’t realize it was an issue till we collided with another car mid-race. Overall this was a pretty fun project and a good way to apply what we learnt in this class.