# Bowed Frame Drum Status: L2 V5 build-packet candidate - organized for prototype/shop review, but not L3/build-ready. CAD/DXF outputs are planned placeholders, acoustic targets are unmeasured predictions, and fabrication authority remains `pending_measurement` until physical validation and reviewed CAD/DXF exist. **Family**: Membranophone — frame drum **Archetype**: Irish bodhran **Target tuning**: C3 fundamental (130.8 Hz), A3 first overtone (219 Hz) **Ergonomic envelope**: 450 mm OD × 90 mm deep, ~900 g ## Design Thesis A bodhran-scale frame drum with a rolled 1.0 mm cold-rolled steel cylinder frame instead of the traditional laminated wood hoop. Inside the frame, a flat CR-steel tone bar (400 × 25 × 1 mm) is suspended on two neoprene grommets and vibrates sympathetically when the head is struck, adding an overtone shimmer near C4 (257 Hz). An optional rosined brass wheel on a cantilevered arm produces a sustained bowed drone in the 80–400 Hz range — transforming a percussion instrument into a hybrid membranophone/bowed instrument. ## Quick Stats | | | |---|---| | Frame OD | 450 mm | | Frame depth | 90 mm | | Frame material | 1.0 mm CR steel, ASTM A1008, butt-TIG seam | | Head | Remo Skyndeep 18" or goatskin, 430 mm playing OD | | Tone bar | 400 × 25 × 1 mm CR flat bar, grommet-suspended | | Tone bar pitch | ~257 Hz (C4 − 27¢), trim-tunable | | Bowing | Optional: 50 mm brass rosined wheel on pivot arm | | Est. build cost | ~$107 USD (materials + bought head) | ## Repository Structure ``` design.md parametric design + geometry narrative parameters.csv all dimensions with units and confidence bowed-frame-drum-starter.wl acoustic model: Bessel membrane + Euler-Bernoulli bar modes bom.csv full bill of materials sourcing.csv supplier SKUs and URLs hardware.csv fasteners and bought hardware cut-list.csv blank sizes and nesting notes bend-table.csv 3 bends with allowance calculations flat-pattern-checklist.md DXF layers, naming, nesting solidworks-plan.md SolidWorks feature tree and global variables fabrication-plan.md 14-step build sequence (Maker Nexus tools) assembly-manual.md final assembly steps + adjustment reference validation.csv target metrics with predicted values tuning-notes.md Bessel physics, screw-to-pitch mapping, bar trimming risks.md safety, manufacturability, acoustic, ergonomic risks photo-shotlist.md 20 required shots for capstone deck visual-bom-brief.md brief for visual BOM illustration visual-output-register.csv V5 visual/CAD/DXF authority ledger cad/mcp-session-log.md V5 MCP/external-tool provenance stub supplier-rfq.md quote-ready RFQ text for sheet stock + head explorer.html interactive packet browser (Heifer Zephyr design language) agent-record.md session log: queries, assumptions, unknowns drawings/ DXF flat patterns (stubs — populate with CAD) cad/ SolidWorks parts + assembly (stubs) cnc/ plasma/laser nesting plan (stubs) learn-to-play/ bodhran technique stub ``` ## License - Hardware (CAD, DXF, BOM, fabrication plans): **CERN-OHL-W v2.0** — see LICENSE-HARDWARE.md - Documentation (markdown, images): **CC BY 4.0** — see LICENSE-DOCS.md --- *Round 5 Percussion — Lane 05 · Heifer Zephyr Instrument Series · v0.1.0-blueprint*