Three Knobs, Three Joints: The Robotic Gripper Arm Kit

The Gripper Arm Kit with Arduino Uno + Servos (₹1,420) builds a 3-degree-of-freedom robotic arm you control directly with your hands — three potentiometer knobs, one per joint. Twist a knob and the matching shoulder, elbow or wrist servo follows in real time; a fourth servo drives a mechanical gripper that picks up bottle caps, erasers and pencil stubs. It is an Intermediate kit with a 5–6 hour build, and its quiet superpower is that the core motion needs no coding at all: the pre-loaded sketch maps knobs to joints, so the arm responds the moment power is applied — then the real learning starts when you open the code. A dedicated 5V 2A supply is included, because four servos on a USB port is a lesson everyone only needs once.

What's in the box

Arduino Uno R3, three SG90 servos, one MG90S servo, three 10kΩ potentiometers, 10kΩ resistors, 100nF capacitors, a 5V 2A power supply, two PCB prototype boards, and 40 jumper wires (25 male-female, 15 male-male). The kit is offered with an assembly option: a soldering bundle (25W iron, solder, flux, perfboard) for permanent assembly, or a breadboard combo (800-point breadboard plus jumper pack) for solderless prototyping — choose based on whether you want a keeper or an experiment.

What you'll learn

• Analog input, properly — reading three potentiometers through the Arduino's ADC and mapping raw values to servo angles, the fundamental input-to-output pattern of embedded control.
• Multi-servo control — driving four servos at once, which immediately teaches power distribution and why the capacitors in the box matter for noise filtering.
• Forward kinematics, intuitively — with three joints under your fingertips, you physically feel how joint angles compose into an end-effector position, the concept every robot-arm course starts with.
• From breadboard to permanent build — the prototype boards let you graduate the wiring into something that survives being handled.

The build, honestly

The electronics are forgiving — knobs and servos are among the most beginner-tolerant components there are — and the mechanical arm assembly is the more fiddly half: servo horns must be attached at the correct neutral angles, and the classic trip-up is mounting a horn one spline-tooth off so a joint hits its limit before reaching where you want it. Centre every servo (the sketch helps) before screwing horns down and the problem disappears. The second lesson arrives on its own: if the arm twitches when several servos move together, that's power-rail noise, and it's exactly what the included capacitors and dedicated supply are for. Both trip-ups are five-minute fixes and both teach things that scale to every bigger robot you'll build.

Who it's for — and who should skip it

A natural fit for Class 11–12 students building control projects, early engineering undergraduates, tinkering-lab mentors who need a reliable workshop arm, and hackathon or tech-fest teams that want a mechanical demo fast. Because motion works without code, it also suits builders who want the mechanics first and the programming second.

Skip it if you want your machine to act on its own — this arm does what the knobs say and nothing more out of the box. For autonomous behaviour with servos and sensing at a similar price, the Colour Sorting Arm Kit adds a colour sensor and decision logic. For a driving robot instead of a desk arm, our Obstacle Avoiding Robot Kit remains the default first build. Experts wanting many-jointed motion should look straight at the Hexapod Robot Kit.

FAQ

Can I control the arm without writing code?

Yes — the potentiometers provide direct analog control and the pre-loaded sketch is ready to run. You can modify it later to add features.

What can the gripper hold?

Lightweight objects up to about 30 grams: foam balls, small erasers, bottle caps. It's designed for educational pick-and-place tasks.

Can I add more degrees of freedom later?

Yes — the Uno has spare pins and timer capacity for extra servos, such as a rotating base or wrist roll.

The kit arrives pre-loaded in Soldr, our AI build assistant, which generates the wiring, the knob-to-joint firmware and troubleshooting for this exact arm.