Motors
STAGE 1B · POWER — The motors that drive every FRC mechanism, and how to read their specs
Motors Are The Source
Every drivetrain, arm, and shooter starts with a motor
- Gears, belts, chain only move power around
- Pick the wrong motor and nothing can fix it
- Specs tell you what a motor can actually do
- Today: read a motor like you read a tape measure
Frame the whole STAGE 1B unit: power generation comes first, then gearboxes (next lesson) transform it. Tell students a gearbox can trade speed for torque but can NEVER create power that the motor doesn't make. Today is about reading datasheets, not CAD-heavy yet, but we will insert real motor models at the end.
Frc'S Main Motors
Brushless is the modern standard — lighter, cooler, smarter
- NEO / NEO Vortex — REV, 1.1in shaft, value pick
- Falcon 500 — integrated controller (Talon FX)
- Kraken X60 — WCP, strongest mainstream brushless
- CIM / 775pro — older brushed, still seen
Most 2024+ robots use NEO, Falcon, or Kraken. Emphasize that Falcon and Kraken have the motor controller built INTO the motor body — one CAN wire, no separate Spark MAX. NEO needs a separate Spark MAX or Spark Flex controller. CIM is what your mentors grew up on; mention it so they recognize it in old robots.
Free Speed
Free speed = max RPM with NO load on the shaft
- NEO ~5676 RPM, Falcon 500 ~6380 RPM
- Kraken X60 ~6000 RPM, CIM ~5330 RPM
- Real mechanisms never hit free speed
- It's the ceiling, then gearing brings it down
Free speed is the spinning-in-air number. Students always over-estimate how fast their mechanism will go — remind them you gear DOWN from free speed and you lose more under real load. Quick math demo: NEO at 5676 RPM through a 9:1 gearbox = ~630 RPM output, before efficiency losses.
Stall Torque
Stall torque = twist when the shaft CAN'T move
- NEO ~2.6 N·m, Falcon 500 ~4.69 N·m
- Kraken X60 ~7.09 N·m (FOC), CIM ~2.41 N·m
- At stall, RPM is zero — max heat
- Never run a motor stalled — it burns out
Stall = pushing against a wall. Torque is highest, speed is zero, and current/heat are at maximum — this is where motors die. Tell the story of a kid who stalled a CIM against a bumper for 10 seconds and smelled smoke. This is WHY we add current limits in motor controller software.
The Power Curve
Speed and torque trade off in a straight line
- Max speed = zero torque (free speed)
- Max torque = zero speed (stall)
- Peak POWER sits in the middle
- Peak efficiency is near the high-speed end
Draw the curve live: x-axis torque, y-axis RPM as a downward line. Power is a parabola peaking in the middle (~half stall torque). Efficiency peaks toward the fast/low-torque side. Key teaching point: you want to design mechanisms to run near peak EFFICIENCY, not peak power, so motors stay cool and last the match.
A gearbox moves power around. It never makes more.
Power = torque × speed. Gear down for torque, gear up for speed — but the motor's max power is a hard ceiling.
Two Motor Families
- CIM, MiniCIM, 775pro, BAG
- Needs Talon SRX / Victor SPX
- Heavier, runs hotter, wears brushes
- Cheap, simple, still legal
- NEO, NEO Vortex, Falcon 500, Kraken
- Built-in encoder, smoother control
- Lighter, cooler, more efficient
- Falcon/Kraken: controller built in
Brushed motors have carbon brushes that physically rub and wear out; brushless use electronics to switch — no wear, less heat. Almost every competitive 2024+ robot is fully brushless. Mention that brushless motors give you a free built-in encoder for closed-loop control, which is huge for swerve and arms.
Motor Controllers
The controller is the throttle between battery and motor
- NEO → Spark MAX or Spark Flex
- Falcon 500 → Talon FX (integrated)
- Kraken X60 → Talon FXS (integrated)
- Set CURRENT LIMITS to prevent burnout
The controller takes battery power and meters it to the motor based on code. Stress current limits AGAIN — this is the #1 way teams kill motors and trip breakers. A NEO is typically limited to 40-60A in code. Integrated controllers (Falcon, Kraken) mean fewer wires and one CAN ID per motor — a real packaging win in CAD.
How To Choose
Match the motor's job to its spec strength
- Drivetrain: 4-8 motors, need torque + speed
- Shooter/flywheel: free speed matters most
- Arm/elevator: stall torque + holding power
- Count your motors — battery limits total draw
Real design constraint: the robot has ONE battery and a finite power budget. You cannot run 12 motors at full current. Swerve already uses 8 motors (4 drive + 4 steer). Teach them to budget: drive motors are the heavy hitters, mechanism motors are what's left. This is why motor choice is a system decision, not per-mechanism.
Insert A Real Motor
Always CAD with the real motor model, never a box
- Download STEP/F3D from REV, WCP, or AndyMark
- Insert > Insert Derive or drag F3D into design
- It comes in as its own Component
- Position with Joints, not free Move
Demo live: go to revrobotics.com, grab the NEO CAD (STEP), then in Fusion use Insert > Insert Mesh/Derive or simply drag the F3D in. It arrives as a component. Common mistake: students model a rough box placeholder and their bolt pattern ends up wrong. The real model has the exact 25-tooth pinion mount, bolt circle, and shaft. Use a Rigid Joint to lock it to the gearbox face later.
Your Task
- Insert a real NEO motor F3D into Fusion
- Make it its own named Component
- Add a sketch note listing free speed + stall torque
- Rigid-joint it to a flat plate face
- Fusion: File > Share > Public Link
- Set link to ON, copy the URL
- Paste the link on AltHub
- Include your free speed / torque numbers
Give them 20-25 minutes. Walk the room. Check that the motor is a real downloaded component (not a box) and that it's a separate component in the browser tree, not loose bodies. The sketch note forces them to actually look up the datasheet values. Submission via Fusion Share public link pasted on AltHub — confirm the link is set to public or you won't be able to open it.
Motors Are The Source Gearboxes Come Next
- Free speed = no load; stall torque = no motion
- Power = torque × speed — gearing can't add power
- Current limits keep motors alive; pick motor to job
Your Task
- Model what this lesson covers in Fusion 360.
- Use the AltSkripts tools where they apply.
- Save it with a clear name.
- In Fusion: Share → Public Link → Copy.
- Paste the link below.
- A coach reviews it in AltHub.