🐦 Woodpecker Automaton: step-by-step build

Turn the handle and the woodpecker pecks: tok-tok-tok-tok!

An automaton is a machine that pretends to be alive. Hundreds of years ago clockmakers built singing birds and writing dolls that amazed kings and queens. The secret inside most of them is a cam: a bumpy wheel. As the cam turns, each bump lifts whatever rests on it. Our cam has four bumps, so every turn of the handle lifts the bird's tail four times — and its beak pecks four times. What brings the tail back down? A heavy tail: the bird is weighted so gravity always pulls its tail onto the cam. Tok-tok-tok-tok!

Level 2 of 5 (easy)
About 20 minutes
16 steps, 50 parts
Powered by: Hand-crank
Series: Mechanical Wonders

What you will learn

Cams: A bumpy wheel that lifts a follower up and down.
Levers: A bar on a pivot multiplies your push.
Centre of Gravity: Keep the heavy stuff low and in the middle and your model won't tip.
Pins: Grippy or Smooth: Pins join beams together — some hold tight, some let things swing.
Axles: An axle is a cross-shaped rod — anything on it turns together.
Frames: A frame is a ready-made strong rectangle.
Triangles Are Strong: A triangle cannot be squished — a square can.

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

1 × Open frame 5×11
12 × Black pin (grippy)
7 × Split pin block
7 × Red axle-pin
1 × L-beam 3×5
1 × Axle 9
3 × Half bush
3 × Bush
1 × Knob wheel
5 × Blue long pin
3 × Beam 5
1 × Hand crank
1 × Axle 4
1 × Beam 9
1 × L-beam 2×4
1 × Beam 7
1 × Beam 13

Steps

Lay the 5×11 frame flat, long side facing you.
Push black pins up into the 2nd and 4th holes of the back side, press a split pin block onto them and push a red axle pin into its middle, pointing out the back.
The same in the 5th and 7th holes: two black pins, a split pin block and a red axle pin.
Press the big L-beam onto both red pins, its short arm standing up at the left. Push a 9-long axle through the arm's middle hole with a half bush behind and a bush in front.
Slide a second bush and the knob wheel onto the axle.
Front: push black pins up into the 2nd and 4th holes of the front side, add a split pin block and a red axle pin pointing out to the front.
Push blue long pins up into the 5th and 7th holes of the front side and press two split pin blocks onto them, one on top of the other.
Push two red axle pins into these blocks, pointing forward, and press a 5-hole beam onto them: the bird's post.
Press a second 5-hole post onto the left red pin, sliding the cam axle into its 2nd hole. Join the tops of both posts with a 5-hole beam and two black pins.
Put the red crank on the front end of the cam axle.
Push a 4-long axle through the 4th hole of the bird's post with a half bush in front and a bush behind. Hang the 9-hole bird on it by its middle hole: its tail rests on the cam.
Lock the bird on with a half bush behind it. Pin the black L-beam to the bird's head as its beak.
Pin a 7-hole beam behind the bird's last two tail holes, pointing away from the head: a heavy tail.
At the back, right in front of the beak: push blue long pins up into the 9th and 11th holes and press two split pin blocks onto them, one on top of the other.
Push two red axle pins into the blocks, pointing out the back, and stand the tall 13-hole tree on them.
Push a blue long pin into the tree as a branch just behind the beak.

Play time

Turn the handle slowly, then fast. Count the pecks in one turn. Cam challenge: swap the knob wheel for a 24-tooth gear with one red axle pin sticking out — now how many pecks per turn?

Real-world inspiration

Cam-driven automata; Kto6Science LEGO cam build — https://kto6science.blogspot.com/2018/01/lego-technic-build-page-142-build-182.html

Build next

⏯️ Geneva Step Counter: Turn the handle smoothly — the pointer moves in jumps: click… wait… click! (level 3 of 5, about 30 minutes, 9 steps)