Harmonograph

A harmonograph is a Victorian drawing machine: two or three pendulums swing, and a pen traces their combined motion until the swing dies out. This toy draws an idealized one.

• Draws an idealized harmonograph straight from the textbook formula for small, damped swings, so no numerical error builds up.
• 9 presets, from a slow 1:1 spiral to dense 5:4 webs and three-pendulum table roses
• Randomize for endless new drawings
• Set frequency, phase, amplitude and damping for each pendulum, plus detune and line weight
• Watch the pen draw, then download it: SVG (vector, ready for a pen plotter, laser or Cricut) or a 2400×2400 PNG
• Print-friendly page
• Fullscreen mode (button or F key)
• Runs in your browser and works offline: download, unzip, open index.html.

Print one for a card or poster: every drawing exports as SVG (sized in millimetres) or a 2400×2400 PNG.

The math is shown under the drawing if you want to know why a 2:3 ratio makes those bands.

Workbench Toys by Spring Pass Co