How to Build a Conveyor Belt with Circuit Cubes

Quick answer

Build a Circuit Cubes conveyor belt by making a sturdy frame with two axles, wrapping a rubber band or tread loop around them, and driving one axle with the Cubit Motor Cube. The motor's planetary gears reduce speed to about 160 RPM, which is slow enough to grip the belt instead of flinging it off. Aim for a snug but not stretched belt; that single adjustment decides whether your build runs or stalls.

A conveyor belt is one of the most satisfying Circuit Cubes mechanical projects because it turns a spinning motor into visible, useful motion. You can load it with bricks, cereal, or tiny toys and watch them travel from one end to the other. The trick is not the electronics; it is getting the frame square and the belt tension right.

This guide walks through the build in order, from planning the frame to testing loads. Each step includes the mistake that most often derails it, so you can catch problems before they turn into a rebuild.

What you need before you start

Gather your Circuit Cubes Bluetooth Cube or battery, a Cubit Motor Cube, and a few structural bricks from your existing collection. For the belt itself, a wide rubber band or a loop of non-slip material works best. You will also want two axles or dowels that spin freely in your frame.

Check that your motor spins before you build around it. If it does not turn, fix that first; troubleshooting a dead motor inside a finished conveyor is far more frustrating than testing it loose on the table.

• Test the motor and battery separately before assembling anything.
• Choose a belt material with grip, not a slick plastic strip.

Build a frame that stays square

The frame is the backbone of your conveyor, and it must hold both axles parallel. If one axle sits higher or closer than the other, the belt will drift sideways and rub the frame. Build two identical side rails, then connect them with cross beams at the same height.

Press every brick firmly. A frame that flexes under belt tension will twist as soon as the motor starts, and you will chase alignment problems that are really structural ones.

• Lay both side rails side by side and compare them before joining.
• Add a cross brace in the middle if the frame feels springy.

Mount the axles and belt loop

Slide each axle through its mounting points so it spins freely with no wobble. Then loop your belt material around both axles. The belt should sit centered on each axle and touch the surface evenly across its width.

A belt that is too loose slips and never moves the load. A belt that is too tight squeezes the axles and makes the motor strain. Adjust the distance between axles in small steps until the belt holds its shape but still flexes slightly when you press it.

• Spin the belt by hand first; it should move smoothly with light resistance.
• If the belt walks to one side, check axle parallelism before adjusting tension.

Connect the motor and drive one axle

Mount the Cubit Motor Cube so its output turns one axle, either directly or through a simple gear or pulley connection. Then connect the motor to your Bluetooth Cube or battery using the supplied wiring. The motor's three ports give you flexibility in how you route the wires, so choose the port that keeps the cable clear of the moving belt.

Keep the wire path away from the belt loop. A cable that brushes the belt will snag, and the first symptom is usually a belt that suddenly jumps or stops.

• Leave a little slack in the wire so it does not pull on the motor.
• Route wires under or behind the frame, not across the belt surface.

Test, load, and tune

Run the conveyor empty for a few seconds. Listen for grinding and watch for belt drift. If it runs clean, place a light object at one end and let the belt carry it. Start with something small and light before trying heavier loads.

If the belt stalls under load, reduce tension slightly or lighten the load. The motor is geared for torque at about 160 RPM, so it pulls steadily rather than fast. A conveyor that moves slowly and reliably is working correctly.

• Run empty first, then add weight gradually.
• A slow, steady belt is normal; speed is not the goal here.

Conveyor build steps at a glance

1. Test the motor loose: Spin the Cubit Motor Cube with your battery or Bluetooth Cube before building around it. If it does not turn now, it will not turn inside the frame.
2. Build two matching side rails: Compare the rails side by side and press every brick firmly before joining them. A flexing frame will twist once belt tension is applied.
3. Mount axles parallel: Slide both axles through their mounts and check that they sit at the same height and distance apart. Uneven axles are the top cause of belt drift.
4. Fit the belt with light tension: Loop the belt around both axles and adjust axle spacing until it flexes slightly when pressed. Too loose slips; too tight strains the motor.
5. Drive one axle with the motor: Connect the Cubit Motor Cube to one axle and wire it to your power source, keeping cables clear of the belt. A snagged wire stops the belt without warning.
6. Run empty, then load: Test the empty belt for drift and noise, then add light objects and work up. Slow and steady at about 160 RPM means it is working.

Parts that make this build work

• Cubit Motor Cube: Cubit Geared Motors are compact and powerful, with tiny planetary gears that reduce the high-speed motor to about 160 RPMs to provide torque to gears, wheels, and similar mechanisms. Three ports around the Motor allow maximum versatility to connect the wires from the Bluetooth Cube. The geared output gives you the torque a loaded belt needs, and the three ports let you route wiring away from the moving loop.
• Plug-to-Clip Wire - 4 Inch / 10 cm: This wire connects your Bluetooth Battery to your LED, Geared Motor, or High Speed Motor. A spare wire keeps your conveyor running if the original connection loosens or gets damaged during play.
• Wheel Rim - 30 x 14 - #56904: Wheel Rim, 30 x 14, #56904, quantity 1. A rim can serve as a pulley or belt guide at the end of your conveyor, helping the belt track straight.

A working conveyor belt comes down to a square frame, parallel axles, and a belt that grips without squeezing. Build it in that order, test as you go, and you will have a mechanical project that actually carries a load.