Glashütte Trash Clock – A 30-minute pendulum clock made from trash

A maker’s project from a residency in Glashütte: a fully functioning 30-minute pendulum clock assembled almost entirely from found trash and salvage. It uses a roughly one‑meter seconds pendulum and a homemade escapement whose wheel is built from paperclip teeth and chosen to have 30 teeth so one full rotation equals one minute (half a tooth per swing). Energy comes from a paint‑can weight driving a cardboard barrel and a simple block‑and‑tackle to double runtime; a second small weight (a rubber boot) powers an independent gong. Instead of precision-cut gears the minute reduction uses easy-to-cut friction discs and axles that can be lifted to set the minute hand. The project also playfully posits a new time scale, GTC, with this device as a reference clock.

Mechanical details include a two‑stage gong trigger: a cam lifts a lever to give a slow “warning,” then a sharp drop releases a pinned drum so a hammer strikes a glass bottle; a fly made from plastic‑bag flags controls strike speed. A final “random complication” is a wheel of fortune labeled NOW/NEVER released by the descending main weight just before power runs out. Video tracking of a marker on the pendulum shows the clock’s average “second” is 1.004 s (±0.001 s), about 0.4% error, demonstrating surprisingly good isochronism for a trash-built timepiece.