Hurricane Foam Dart Blaster Modification
Overview
Completed June 2023
The goal of this project was to make a pistol sized foam dart blaster (aka a Nerf gun) shoot as fast as possible for something that compact. The stock blaster uses two DC motors that spin up a pair of flywheels to propel the dart forward. However as the fine people at Foamblast discovered, with some slight modification to the shell and a custom 3D printed flywheel cage you can fit a second set of motors and flywheels into the blaster. I really liked their design and after 3D printing one of theirs I decided I wanted to make my own version to be CNC machined out of aluminum. The metal cage helps slightly with the loud noise from the two sets of motors, but this project was mostly done as an excuse to grow my skills as a CNC machinist.
Machining
The custom cage was modeled in Fusion 360 and machined out of 6061 aluminum on a Haas VF4 CNC mill. The part was machined in two operations using a custom made fixture plate. The first op machined the general profile of the cage, the motor wells, and the tapped holes to secure the part to the fixture plate. The fixture plate was machined to locate the part off of the four motor wells using the bore on the front of the plate to establish a work coordinate system. The final op of the part cleared our the rest of the material on the cage, and added some small surfacing details for decoration.
Electronics
The blaster uses four Out of Darts Loki motors. These are a 130 sized high rpm DC motor designed specifically for the foam blaster hobby. The motors are powered by a small 3s LiPo battery that fits in the handle of the blaster shell. The blaster functions using a duel stage trigger. Pulling the trigger halfway releases the rev switch which starts the motors, and pulling the trigger all the way pushes a dart into the flywheels. Due to the high stall current of the motors, the system is protected by a custom PCB designed by DevilZ Nerfworks. The boards include a MosFET that will protect the switch in the system from burning out should the motors become jammed. There is also a small capacitor on the board that keeps the motors running for a second after the rev switch is released which helps to reduce the chance of accidently jamming a dart into unpowered flywheels when repeatedly pulling the trigger.
