# Decision Record ## Decisions - Treat the Cristal Baschet as a glass-rod friction idiophone with a modular rod-to-stem-to-radiator transmission chain. - Promote the packet from L1 concept to L2 planning by adding subsystem shop interfaces, a non-dimensional cut/workpiece list, and explicit measurement gates. - Keep all dimensions, tuning, pressure values, thread specs, resonator coordinates, mass positions, CAD, and DXF work out of this packet. - Make the first physical work a single-rod bench rig before any full sculptural frame. - Treat the whisker radiator as a safety-critical experimental surface rather than a decorative afterthought. - Keep all visual/CAD authority at `concept_only` or `pending_measurement` until measured references or reviewed design tables exist. ## Assumptions - Wet fingers excite glass rods through stick-slip friction. - Vibration is transmitted through metal stems, with threaded hardware and movable masses used as setup variables. - Cone/flap resonators and a whisker radiator are candidate radiation surfaces. - Final pitch, response, sustain, and tuning must come from measurement, not from this concept packet. ## Open Questions - What measured or museum/reference instrument should govern the first L2 parameter set? - Which glass stock and mounting approach can be tested safely in a one-rod rig? - What stem and movable-mass arrangement provides adjustment without rattles? - Which radiator family should be tested first: cone, flap, whisker, or a deliberately minimal reference plate? - How should broken-glass, fiber, edge, moisture, and transport risks be controlled before any public demo? ## L2 Promotion Gates - Select a real rod stock and document the source before cutting or mounting. - Define a rod support and stem-coupling test that can be inspected after each play session. - Prepare a mass-sweep log that records setup labels and observations without publishing final tuning coordinates. - Compare cone, flap, and neutral radiator coupons from the same rod/stem rig before designing a full frame. - Complete whisker handling and containment review before making it a public performance surface. - Keep future CAD/DXF blocked until the cut-list categories have measured dimensions and authority owners. ## Next Work - Select reference evidence for rod/stem/radiator architecture. - Build a one-rod excitation and transmission test rig. - Log mass sweep behavior without publishing final tuning claims. - Compare one modular cone/flap radiator and one whisker-safe mockup. - Record safety observations before upgrading readiness.