How to Design an FRC Intake: Rollers, Compression, and Motors

The intake is the mechanism that decides whether your robot ever touches a game piece. A brilliant shooter or a fast elevator is worthless if the robot can't reliably pick up the object in the first place, and every season the teams that score in a hurry are usually the ones whose intake is wide, forgiving, and hard to jam. This guide walks through how to actually design one: the major architectures, how compliance and compression really work, how to lay out rollers, and how to pick and current-limit a motor. Wherever a number matters, it's tied to a primary source you can check yourself.

One note before the details: intakes are the single most game-specific mechanism on the robot, because the game piece changes every year. The principles below are evergreen, but the exact dimensions, roller diameter, and compression you land on come from prototyping against this year's actual game piece. Design the process, not the part.

What an intake actually has to do

Strip away the game and an intake has four jobs:

1. Reach the game piece (get a grabbing surface to where the object is).
2. Grip it (transfer enough friction to overcome the object's weight and inertia).
3. Control it (move it to a repeatable, known position — a "seated" pose).
4. Hand it off to the next mechanism (indexer, shooter, elevator) or hold it.

Almost every design decision is a tradeoff between these four plus the constraints of the rules. Keep the list in front of you: when someone proposes a clever geometry, ask which of the four it improves and which it sacrifices.

The rules that bound every intake

Intakes live at the edge of the robot, so the construction rules bite harder here than almost anywhere else. As of the 2026 REBUILT season, the FRC robot rules set these limits (always re-read the current game manual — these numbers do get revised year to year):

• Frame perimeter must be ≤ 110 in, and starting height ≤ 30 in.
• Horizontal extension: the robot may not extend more than 12 in beyond the vertical projection of its frame perimeter.
• Bumpers must not extend more than 4.0 in from the robot perimeter; the hard structure of a bumper may not extend more than 1.25 in.
• The bumper zone is the band 2.5 in to 5.75 in off the floor that bumpers must fill.

Two design consequences fall out of this. First, an intake that reaches out to grab pieces beyond the frame is spending your limited extension budget — plan for it and know how far you can legally reach. Second, because bumpers occupy a fixed 2.5–5.75 in band around the whole robot, any intake that grabs pieces off the floor has to deal with the bumper as an obstacle. That single fact drives the biggest architectural choice you'll make.

Verify the extension and frame numbers against the current manual every season. FIRST changes frame perimeter limits and per-game extension rules, and inspectors check these at every event.

Over-the-bumper vs. under-the-bumper

Because the bumper sticks out and sits in a fixed height band, a ground-pickup intake has to get the game piece past the bumper. There are two ways to do that.

Over-the-bumper (OTB). The intake reaches out over the top of the bumper, grabs the piece, and pulls it up and back into the robot. This is the dominant modern floor-intake architecture. The grabbing rollers start inside or above the frame and swing out over the bumper on an arm — very often a four-bar linkage so the roller stays at a consistent angle through its travel. OTB intakes can be very wide, can pick pieces up flush against a wall, and don't require a gap in your bumpers. The cost is that the mechanism lives outside the frame perimeter, so it's exposed to contact and has to be built robust — this is one of the classic intake "golden rules" from veteran design resources.

Under-the-bumper (UTB). The intake pulls the piece underneath the bumper through a gap. This needs a deliberate bumper gap (the rules permit gaps within limits — a single larger gap is allowed as long as enough perimeter around each corner stays protected), and it limits you to game pieces short enough to fit under the ~2.5 in bumper-bottom clearance. UTB intakes can be extremely low, simple, and fast, and they tuck the mechanism safely inside the frame. They shine for short pieces (discs, low cubes, some balls) and struggle with tall ones.

A quick decision heuristic:

• Game piece taller than the under-bumper gap, or you want to grab pieces flush against a wall → over-the-bumper.
• Game piece short, and you value simplicity/robustness → under-the-bumper.
• Not sure → prototype both against the real piece; it's cheap and answers the question in an afternoon.

There are also fixed intakes that don't deploy at all (the grabbing surface always sticks out) versus deploying intakes that stow inside the frame and pivot or extend out. Fixed intakes are dead simple and can't fail to deploy, but they permanently eat frame-perimeter and extension budget and are exposed the whole match. Deploying intakes protect the mechanism and free up space but add a degree of freedom, a motor or pneumatic actuator, and a failure mode. Most competitive OTB intakes deploy.

Roller vs. wheel: the compliance question

Whatever the architecture, something spinning has to touch the game piece and drag it in. The two families are rollers and wheels, and the real distinction is about how compliance is distributed.

Compliant wheels are discrete rubber wheels spaced along a shaft. AndyMark's compliant wheels — a de-facto standard part — come in four hardnesses, color-coded, and the hardness (durometer) is the whole point:

They're offered in 2 in, 2.25 in, 3 in, and 4 in diameters and several hex bores (1/2 in, 3/8 in, 5 mm) plus a nub option. The manufacturer is blunt about their purpose: they are "not intended for moving robots, but moving objects" — they "give way to allow rigid objects to be manipulated easily." For intakes, the standard advice is lower durometer for more grip and more give, because a soft wheel conforms around the object and maximizes contact patch. A row of compliant wheels on one driven shaft forms an effective "roller" that tolerates variation in the object's size and shape.

Rollers are continuous cylinders — a polycarbonate or aluminum tube, a 3D-printed sleeve, or a tube wrapped in a grippy material like surgical tubing or urethane. Compared with spaced wheels, a full-length roller gives more consistent compression across the whole width of the game piece and tends to be cheaper, lighter, and easy to mount on a dead axle (more on that below). The tradeoff: a rigid roller has less "give," so with a hard object you rely on the grippy surface material rather than the roller deforming.

This leads to the most useful single rule in intake design, straight from veteran design guidance:

If the object is squishy, make your rollers rigid. If the object is hard, make your rollers compliant/squishy. You need deformation somewhere in the system to create a contact patch — either the object gives or the roller gives.

So a soft foam ball wants a hard roller; a rigid plastic cube or a hard hollow ball wants soft compliant wheels or a tubing-wrapped roller. Match the pair.

Surgical tubing intakes deserve a mention as a third option: latex tubing spun at high RPM (often 800–1000+ rpm) is extremely grippy, conforms to almost any shape, and can grab several pieces at once. The cost is control — tubing intakes are less precise about where the piece ends up and wear faster. They're a great choice for "just get it in the robot" designs and a poor one when the piece must land in an exact seated position.

Compression and wrap: where grip actually comes from

Two geometry parameters do most of the work in a roller intake: compression and wrap.

Compression is how much closer the roller centerline sits to the opposing surface (a wall, a floor, a second roller, or a polycarbonate guide) than the game piece's free dimension. If a ball is 5.0 in across and you set the roller-to-wall gap to 4.6 in, you have 0.4 in of compression. That squeeze is what generates the normal force, and normal force times the coefficient of friction is your grip. Too little compression and the piece slips; too much and the motor has to fight to turn the roller and the piece can bind or get chewed up.

You don't compute the ideal compression — you prototype it. A common starting point for compliant-wheel and roller intakes is on the order of ¼ in to ½ in of compression, then adjust: veteran build blogs describe tuning flywheel and feeder compression in exactly this range and finding that even a half-inch change "drastically" alters behavior. The important design principle: prefer a grippier roller surface over cranking up compression. More compression means more required torque and more wear; a better surface material gets you grip for free. Set compression by moving the roller center-to-center distance (shims, adjustable mounting slots, or an idler you can reposition) and lock it in once prototyping settles.

Wrap is how much of the game piece's surface the roller (or belt) contacts — think of the arc of contact. More wrap means more contact area and more chances to grab, which is why so many intakes route a belt or a second roller around the piece to increase the wrapped angle rather than relying on a single tangent point. Curved polycarbonate guides opposite the roller are a cheap way to increase effective wrap and funnel the piece toward its seated position.

Roller layout: dead axle, live axle, and driving both sides

Dead axle vs. live axle. On a live axle the shaft itself spins and the rollers are keyed to it. On a dead axle the shaft is fixed and the rollers spin on bearings around it. Dead axles are a favorite for intakes because the fixed shaft doubles as a structural standoff tying the two intake side plates together — you get a rigid assembly and free-spinning rollers at once. It's often cheaper and lighter, too. Use a live axle when you need to drive the roller directly through the shaft or transmit torque down its length.

Power both sides. A wide roller driven from only one end can wind up and deflect. For anything but the shortest rollers, drive from both ends or use a stiff shaft; better yet, put the drive at the roller and keep the transmission short.

Surface speed, not RPM. The number that matters isn't roller RPM, it's the surface speed of the roller where it touches the piece (roller circumference × RPM). The classic golden rule: the roller's surface speed should be at least about double the robot's maximum drive speed. The intuition is that the piece is entering the robot's frame as the robot drives forward; if the roller surface isn't moving inward faster than the robot is moving toward the piece, the piece gets pushed away or plowed rather than pulled in. Size your gear ratio so a 2–4 in roller hits that surface speed at your motor's loaded RPM.

A few more layout rules of thumb worth internalizing:

• Maximize width. A wide intake makes both autonomous and teleop pickups vastly more forgiving — you don't have to aim precisely. Width is the cheapest reliability you can buy.
• Funnel toward a seated position. Use angled side plates and guides so the piece self-centers to one repeatable spot. A known seated position is what lets the next mechanism (indexer/shooter) be simple.
• Add a sensor. A beam-break or the motor controller's current spike tells software a piece is captured, so autonomous routines and driver feedback can react. This is on every serious team's golden-rules list.
• Build it to survive contact. OTB intakes live outside the frame and will get hit. Use robust standoffs, avoid fragile 3D-printed structural parts in the impact path, and make rollers easy to swap.

Choosing and current-limiting the motor

Intakes are, mechanically, a low-continuous-load job punctuated by brief stalls (when a piece jams or is first grabbed). That profile points to a small, responsive brushless motor with good thermal behavior, geared down enough to produce torque at the roller. Here are the common FRC-legal options with manufacturer-published specs:

(Free-speed figures vary slightly between the manufacturer datasheet and dyno testing; use the vendor's published number for your specific controller and firmware.)

For most intakes the NEO 550 or Kraken X44 is the sweet spot: enough power, small package, and the X44's integrated controller saves wiring and space. Reserve the big drivetrain motors (Kraken X60, full-size NEO/Vortex) for cases where you genuinely need the torque, such as a heavily geared intake that also has to power an indexer.

Gearing. Take the motor's loaded RPM (well below free speed) and a chosen roller diameter, and pick a reduction that lands your surface speed at ~2× robot speed with headroom. A single stage of 3:1 to 5:1 into a 2–4 in roller is a typical ballpark; confirm with a calculator against your real numbers.

Current limiting is not optional. Intakes stall regularly — that's normal operation, not a fault. At stall a NEO 550 will try to pull 100 A and a Kraken X44 far more; left unlimited, that cooks the motor, pops breakers, and browns out the robot. Every modern smart controller can cap phase current:

• REV SPARK MAX / SPARK Flex have a configurable Smart Current Limit that trims duty cycle to hold phase current at your set point.
• CTRE Talon FX (Kraken/Falcon) exposes stator and supply current limits.

Set an intake current limit well below stall — teams commonly run intakes in roughly the 20–40 A range, tuned so the roller grips and stalls gently without tripping the ~40 A main breakers on that circuit or overheating the motor during a long hold. Start conservative, watch motor temperature and behavior, and raise it only if the roller can't grab under limit. The NEO 550 in particular has lower thermal mass than bigger motors, so it heats quickly under a sustained stall — respect the limit.

A sane design process

Pulling it together, here's the order of operations that keeps you out of trouble:

1. Study the game piece. Weigh it, measure it, feel how squishy it is, note where it needs to end up. Every later choice depends on this.
2. Pick the architecture — OTB vs UTB, fixed vs deploying — from the piece height and where it sits on the field.
3. Prototype the grabbing surface. Cardboard-aided and hot-glue prototypes are fine. Try compliant wheels of a couple durometers and a tubing-wrapped roller. Match rigid-to-squishy per the golden rule.
4. Tune compression and wrap on the prototype with the real piece, starting near ¼–½ in and adjusting. Prefer better grip material over more squeeze.
5. Set the geometry — width as wide as legal/practical, funneling guides, four-bar or pivot for deployment, roller center distances lockable.
6. Choose the motor and gear for surface speed ≥ ~2× robot speed, then set a conservative current limit and add a piece-detection sensor.
7. Build it robust, test it hundreds of times, and make rollers and surfaces easy to swap when they wear.

Do those in order, prototype against the actual game piece, and verify each rule number against the current game manual, and you'll have an intake that quietly does its job all season — which is exactly what a great intake is supposed to do.

Frequently asked questions

Should my rollers be soft or hard? Match the object. Hard/rigid game piece → soft compliant wheels (35A/40A). Squishy game piece → rigid rollers. You need give somewhere to form a contact patch.

How much compression should I use? Start around ¼–½ in and prototype from there. If the piece slips, add grippier surface material before adding compression — more compression costs torque and wear.

Over-the-bumper or under-the-bumper? Tall pieces or wall pickups → over-the-bumper. Short pieces where you want simplicity and protection → under-the-bumper. Prototype both if unsure.

What motor is best for an intake? For most teams the NEO 550 or Kraken X44 — small, responsive, and (for the 550) explicitly designed for intakes. Always current-limit it, because intakes stall as part of normal operation.

How fast should the roller spin? Fast enough that its surface speed is at least about twice the robot's max drive speed, so it pulls pieces in faster than the robot drives toward them.