Make a LEGO® PinchBot
Build a LEGO PinchBot that pinches and picks small objects using gears, levers, and rubber bands, learning about simple machines and problem-solving.
About this activity
Build a LEGO PinchBot that pinches and picks small objects using gears, levers, and rubber bands, learning about simple machines and problem-solving.
What you need
Step by step
- 1
Step 1
Gather all the LEGO pieces gears rubber bands and small objects you will use and put them on your workspace.
- 2
Step 2
Build a sturdy rectangular base by snapping plates and bricks together so it will hold your PinchBot steady.
- 3
Step 3
Build two vertical supports on the base and place them about four to six studs apart where the claw will sit.
- 4
Step 4
Slide a long axle through the two supports so it can spin freely left to right.
- 5
Step 5
Attach one lever beam to the axle on one side and attach a second lever beam to the axle on the opposite side so the two beams act as the two halves of a claw.
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Step 6
Hook a rubber band between the outer ends of the two claw beams so the rubber band pulls the beams together to make a pinch.
- 7
Step 7
Fix a small gear onto the claw axle so the gear turns whenever the claw axle turns.
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Step 8
Build a crank axle behind the supports and add a larger gear and a small handle or wheel to the crank axle.
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Step 9
Position the crank gear so it meshes with the claw gear and make sure turning the crank makes the claw axle rotate.
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Step 10
Turn the crank to open the claw place a small object between the claw ends then release so the rubber band closes the claw and lifts the object.
- 11
Step 11
If the grip is too weak move the rubber band one stud closer to the claw tips to increase the pinch strength.
- 12
Step 12
Take a photo or short description of your finished PinchBot and share it on DIY.org
Fun facts
How do you build a LEGO PinchBot that pinches and picks up small objects?
Start by sketching a simple gripper design, then build a sturdy base from LEGO beams and plates. Add axles, gears, and a crank or motor to create rotational motion. Connect a lever arm to the gear train that opens and closes two claw pieces; use rubber bands for return tension. Test with small objects, then tweak gear ratios, lever lengths, and band tension until the pinch action is reliable.
What materials do I need to make a LEGO PinchBot?
Gather LEGO Technic beams, liftarms, and plates for a strong frame, plus axles, connectors, bushings, and gears (spur and bevel as needed). You’ll want two claw pieces or compatible bricks for grippers, several rubber bands for tension, and a motor or hand crank for movement. Add small tools (axle remover), a tray of small objects to pick, and optional stickers for decoration. Keep spare parts for adjustments.
What ages is building a LEGO PinchBot suitable for?
This project suits children roughly aged 6–12, with variations: ages 6–8 can build simple pinchers with adult help, while 9–12 can handle more complex gear trains and independent troubleshooting. Younger children benefit from guided steps and supervision around small pieces. Teens and adults can expand the design with motors, sensors, or programmable bricks for advanced STEM learning.
What are the benefits and safety tips for making a LEGO PinchBot?
Building a PinchBot develops fine motor skills, spatial reasoning, and understanding of simple machines like gears and levers while fostering creative problem-solving. Safety tips: supervise children under 8, keep tiny parts away from toddlers to prevent choking, avoid overstretching rubber bands, and disconnect motors before hand adjustments. Work on a clear surface and store loose pieces in containers to prevent trips and lost parts.
Watch & Learn
Need help?
What can we use if we don't have the exact LEGO gears, axles, or rubber bands listed?
If you can't find the specified small gear, larger crank gear, or Technic axle, substitute any similar-sized Technic gears or a 2x2 turntable plate for the gear, a long Technic axle or a wooden skewer through the supports, and small hair elastics in place of the rubber band hooked between the claw beams.
The crank turns but the claw doesn't move — what should we check?
Check that the crank gear is positioned so it meshes with the claw gear and that the claw axle spins freely through the vertical supports (loosen tight bricks or re-seat the axle) so turning the crank rotates the claw axle as instructed.
How can we adapt the build for younger or older children?
For younger builders, pre-build the sturdy rectangular base, vertical supports, and crank axle and let them attach the claw beams and rubber band, while older kids can swap lever beams for longer liftarms and add extra gears to experiment with gear ratios and lift heavier objects.
How can we improve or personalize our PinchBot after it's working?
Add a second larger gear to change speed and torque, move the rubber band one stud closer to the claw tips to increase pinch strength as suggested, swap in different lever beams for new claw shapes, and decorate the base with colored plates before taking a photo for DIY.org.