⏱️ Pendulum Metronome: step-by-step build

Give it a nudge: tick… tock… tick. Move the wheel to another hole and count again!

A pendulum is a weight that swings back and forth below a pivot, and clocks have used pendulums to keep time for hundreds of years. You are going to build your own swinging timer. The yellow beam hangs on a short axle with a half bush on each end, and the heavy yellow wheel at the bottom is the bob. Give it a nudge and say tick each time it reaches an end: out and back again is one full swing, so two ticks make one swing. Then move the wheel up to another hole and count again.

Level 1 of 5 (super easy)
About 10 minutes
9 steps, 27 parts
Powered by: Gravity
Series: Mechanical Wonders

What you will learn

Pendulum: A swinging weight keeps steady time.
Frames: A frame is a ready-made strong rectangle.
Pins: Grippy or Smooth: Pins join beams together — some hold tight, some let things swing.
Centre of Gravity: Keep the heavy stuff low and in the middle and your model won't tip.
Triangles Are Strong: A triangle cannot be squished — a square can.

Parts you need

1 × Open frame 5×7
8 × Black pin (grippy)
2 × Cross block
2 × Long pin-axle block
1 × Axle 7
2 × Beam 11
2 × Beam 7
3 × Half bush
1 × Axle 3
1 × Axle 5
1 × Bush
1 × Yellow-hub wheel
2 × Blue long pin

Steps

Lay the 5×7 frame flat on the table. This is the stand's foot.
Push a black pin up into the two corner holes of the back row. Put a cross block on each pin, its cross hole pointing sideways behind the frame.
Hold a long pin-axle block upright at each end and slide the 7-long axle through both of them and both cross blocks.
Push two black pins backwards into each upright block.
Stand an 11-hole beam behind each block and press its 1st and 3rd holes onto the pins.
Push a black pin into the top hole of each post and join the posts with a 7-hole beam.
Put a half bush on one end of a 3-long axle and push the axle through the middle hole of the red beam from behind. Hang a 7-hole beam on the axle by its top hole, then push a second half bush on the front end.
Push a 5-long axle through the bottom hole of the swinging beam. Put a half bush on the back end, then a bush and the yellow wheel on the front end.
Push a blue long pin into the 9th hole of each post, sticking out to the front, as swing stoppers.

Play time

Nudge the pendulum gently and count full swings (out and back) for 10 seconds. Now move the wheel with its axle and bushes up two holes and count again: faster or slower? Try a big swing and a small swing: do they take the same time? Count them and see.

Real-world inspiration

Galileo's pendulum and the musician's metronome — https://en.wikipedia.org/wiki/Metronome