#017 DIY Nerf Gun

For many of my projects, I have to delve into new sets of materials in order to find the optimal material for a part. With the DIY Nerf Gun, PLA, a common 3D printer material, was a perfect choice. After all, Nerf Guns are traditionally made out of hard plastic. What this meant was that Luka and I could simply do a few sketches on paper, use Fusion 360 to model the parts, and have strong (enough) parts in hours. Manufacturing the complex shapes we used to route the balls would have been nearly impossible without the 3D Printer.

One aspect of the gun that I knew would need a lot of focus was making sure the balls did not jam up as they were fed between the flywheels. We achieved this by having a convex roller that agitated the balls while also centering them into a single stream. This proved mostly effective. We did have some issues originally, but they were resolved by changing the space between the roller and the wall. We powered the roller with a DC motor and four AA batteries. A simple switch toggled the roller on and off.

We used some foam mounting plates to secure the flywheels to the roller / agitator. The flywheels were simply two brushless (1000KV) RC motors. We ran them on a 3s lipo, so they probably spun at around 11000 RPM. I designed and printed a simple doughnut shape that slid atop the motor casing. It allowed the outer radius of the motor to be moving at a faster speed.
Since the original print, the outer edge has begun to wear. When I print the next cover, I will increase the radius: The brushless motors were easily able to supply enough torque to shoot a stream of balls. Hopefully I can increase the muzzle speed this way.