What is a cam, and what does it do?

A bumpy wheel that lifts a follower up and down. A cam is a wheel that is not round — it has a bump. As it spins, the bump lifts whatever rests on it, then lets it drop. The bump shape decides the movement: tap, lift, or wiggle.

Try Woodpecker Automaton for free

Mechanical Wonders booklet pack: 30 PDF booklets for $5.99. Instructions only; individual booklets remain free.

Explore the printable pack

Try it yourself

Put two bumps on the cam instead of one. How many taps per turn now?

Build it: 2 builds that teach cams

  • 🐦 Woodpecker Automaton: Turn the handle and the woodpecker pecks: tok-tok-tok-tok! (level 2 of 5, about 20 minutes, 16 steps)
  • 🥁 Cam Drummer: Crank the handle and two drumsticks play a beat all by themselves. (level 3 of 5, about 30 minutes, 18 steps)

In the classroom

Common engineering questions

How can I try cams at home?

Put two bumps on the cam instead of one. How many taps per turn now?

Which builds teach cams?

2 MightyCog builds teach it: Woodpecker Automaton and Cam Drummer. Start with Woodpecker Automaton: 16 steps, about 20 minutes.

Ideas that go with it