🦀 Lazy-Tongs Grabber: step-by-step build

Squeeze the handles and the criss-cross arms shoot out to grab things far away!

Lazy tongs are a grabber for people who don't want to get up from the sofa. They are made of X shapes joined in a chain. When you close the first X a little, every X closes a little too — and all those little moves add up to one BIG reach. Engineers call beams joined by pins a linkage. Build four X's, add handles and a pair of claws, and go sock hunting!

  • Level 2 of 5 (easy)
  • About 20 minutes
  • 11 steps, 32 parts
  • Powered by: Hand-crank
  • Series: Mechanical Wonders

What you will learn

Build these first

  • ⚖️ Balance See-Saw: A see-saw that is also a scale. Can one gear beat two? (level 1 of 5, about 12 minutes, 10 steps)

Parts you need

  • 8 × Beam 7
  • 16 × Grey pin (smooth)
  • 2 × Beam 9
  • 2 × Boomerang beam 3×7
  • 2 × Red axle-pin
  • 2 × Bush

Steps

  1. Lay a 7-hole beam on the table at a slant. Push a grey pin in its middle and cross a red 7-hole beam over it.
  2. Push grey pins into the two front ends. Add the next slanted beam and its middle pin.
  3. Cross the next red beam, then push grey pins into the front ends.
  4. Add the third X: a grey beam, a middle pin and a red beam.
  5. Push in grey pins at the front and build the fourth X.
  6. Finish the fourth X with a middle pin and a red beam.
  7. Handles: push grey pins into the back ends and add a 9-hole handle.
  8. Pin the second handle so the handles cross like scissors.
  9. Claws: push grey pins into the front ends and add the first boomerang claw.
  10. Pin the second claw on top so the claws cross.
  11. Push red axle pins into the claw tips and add bushes as soft grips.

Play time

Squeeze the handles and watch the tongs zoom forward. Try to pick up a sock, a paper cup or a toy car from far away! How much farther do the claws move than your fingers?

Real-world inspiration

Lazy tongs / pantograph linkage — https://en.wikipedia.org/wiki/Lazy_tongs

Build next

  • 🌬️ Oscillating Fan: A desk fan that turns its head left and right all by itself! (level 3 of 5, about 40 minutes, 18 steps)