How it works
- A chain wound in coils on a horizontal stick. A winding motor turns the stick; a tilt motor tips the whole assembly forward. When the stick tips, the coils slide off the free end together and free-fall onto the target as one dense crash. Tilting back and rewinding resets it.
- The drop is as fast as gravity, because nothing has to unwind. Tilting is the trigger and rewinding is the reset.
- Chain end is anchored at the motor end of the stick, so the chain never leaves the unit. After a drop it hangs from the anchor over the tip; rewinding lifts it back off the target, which makes its own scraping sound.
Building the stick
- Getting the coils to slide off: slick stick (polished rod or PTFE sleeve), slight taper toward the tip.
- Winding evenly: feed the chain on near the motor end so new coils push earlier ones toward the tip, like a capstan.
- Tilt angles: wind level or tipped slightly back; drop at a steep forward angle. Find both by testing.
- Link chain coils and slides better than ball chain for this design.
Sensing
- Sensing for unattended reset: limit switch at each tilt position, a count of winding turns, stall detection on the winding motor.
Timing
- Free fall takes about 0.32 s from 0.5 m and 0.45 s from 1 m, plus slide-off time. A fixed lead time per unit lets the crash land on the beat.
- Several units on one bar take turns: one drops while the others rewind, so patterns can run faster than one unit’s rewind time. Different chains, drop lengths, and targets per unit make the bar a small kit.
Targets
- Targets: cymbal, sheet metal, and especially snare drum, where the snare wires add buzz.
Brush mode
- Leave the chain uncoiled, hanging over the tip with its tail resting on the drum head. Slow partial turns of the stick pull the chain up over the tip and let it back down, dragging the tail across the head for a brush-like sound. An anchor set off the stick’s axis would add a circular swirl.