Shooter
High-RPM flywheel with hooded geometry. Tight tolerances and balanced rotating mass for repeatable shots — the foundation for any projectile scoring.
Before you start
Decide on a single-flywheel or dual-flywheel design. Dual flywheelTwo opposed wheels grab the piece from both sides — better launch energy and less reliance on hood friction. But you need two motors or a transfer belt to drive both. shoots harder; single-flywheel is simpler and lighter.
1Calculate the launch RPM you need
Treat the piece as a projectile: launch velocity = (gravity × range)^0.5 × something-something. Compute the surface speed you need at the flywheel, then back into RPM via wheel diameter.
Target ~10–20% above your minimum so you have margin for game piece wear and friction losses.
2Pick and size the flywheel
Flywheel diameter trades surface speed for rotational inertia. Larger wheels at lower RPM are more forgiving; smaller wheels at higher RPM accelerate faster between shots.
Compliance on the flywheelA bare aluminum flywheel will slip on the game piece. Wrap it with grip tape or use a compliant tread for the piece to grab against. Surface texture is half the launch energy. matters as much as the RPM.
3Design the hood
The hood is the curved plate above the flywheel that guides the piece. Hood angle sets the launch trajectory; hood-to-flywheel gap sets the compression on the piece.
Compression should squish the piece by 10–20% of its diameter — too little and it slips, too much and you bog the motor.
4Balance the rotating mass
Print or machine the flywheel concentric to its hex bore. Imbalance vibrationA 1mm offset of mass at 5000 RPM creates forces large enough to shake the whole robot. Always cut a flywheel symmetric, or balance it after printing by drilling small holes opposite heavy spots. at high RPM will tear bearings out of mounts.
Use the same hex shaft / bearings sub-assembly from the bearing-stack tutorial — same parts, different scale.
5Mount and stress-test the assembly
Bolt the shooter to the chassis through a stiff bracket — flywheel vibration transmits through any flex point. Spin the motor up to target RPM in the assembly and confirm clearance around the flywheel envelope.
Add a feeder gate that admits exactly one piece at a time — feeding two pieces at once double-loads the motor and crashes the RPM mid-burst.
You have a repeatable shooter. The hard part is now ammo management — making sure pieces arrive at the flywheel one at a time, the same way each time.