The sambuca is Tony Koop's reinterpretation of the Sumerian boat-shaped arched harp recovered from the Royal Tombs at Ur (British Museum object 121198, c. 2600 BC). The pattern is 4500-year-old visual fingerprint — boat hull, curved cantilever neck, gold-flared cap, multi-strip lapis seam band, row of bulb tuning pegs with cord wraps, bow-end inlay panel, integral stern stub feet — and full design freedom on every dimension underneath.
Five planned variants (SAM-13 through SAM-25), all from one SolidWorks MasterLayout part. SAM-13-ROOT is the prototype build target; the other four are documented as Pack-and-Go siblings.
Body length
650 mmSAM-13-ROOT
Strings
13G3 → E5 diatonic
Total tension
65–80 kgfcalibrated
Wood pairing
Walnut + cedar + sapelehull / soundboard / neck
Soundhole
Single oval keel port80 × 50 mm, fwd-tilt 15°
Playing position
Seated symmetriclong axis between thighs
Capstone window
Fall 2026~Oct–Nov
License
DualCERN-OHL-W-2.0 (design) + CC-BY-4.0 (content)
Cultural provenance
Inspired-by, not a reproduction. The pattern itself is unambiguously public domain (4500 years). Only the surviving gold tuning pegs and lapis lazuli decorations from BM 121198 are original Sumerian material; the wood is a 1971–72 reconstruction. Full provenance language locked in design.md pending the cultural-advisor review gate. reverse-engineering.md documents BM 121198 + the Royal Cemetery cylinder seal (Penn Museum B16728).
Four documents form the design foundation. Read them in order if you're new to this repo; they're each several pages so they live in dedicated files rather than embedded here.
▶reverse-engineering.mdMDAnalysis of BM 121198 + Royal Cemetery cylinder seal — taxonomy locked, dimension anchors measuredOpen
Reverse-engineered observation pass on BM 121198 (the British Museum boat-shaped arched harp from the Royal Cemetery at Ur). Taxonomy is locked: boat-shaped arched harp / sambuca, not a lyre — confirmed by the BM curator card. Dimension anchors measured: body length 650 mm, width 150 mm, instrument height 810 mm, 13 strings. Surviving original Sumerian material: gold tuning pegs and lapis lazuli decoration only — the wood is a 1971–72 reconstruction.
The full document contains observed facts (BM display photo + Herbology Manchester profile + second photo set), inferred facts with confidence ratings, assumptions, unknowns assigned to next-phase work, mechanism hypothesis, dimension anchors locked into SolidWorks parameters, material/process notes, and three queued next-handoffs (SolidWorks MasterLayout build, Wolfram Cloud acoustic study, instrument-maker-v4 build packet). Open the full file →
The design canon. Covers family (5 variants, all from one MasterLayout), soundhole strategy (single oval keel port — modern functional improvement, projects forward toward listener), quiet-instrument mitigations, variable-string-count tuning peg positions, string termination (no separate bridge bar — standard arched-harp practice), neck-to-body joint candidate trade study, stand joinery, playing position and harness, materials slate, tuner choice (zither pegs locked 2026-05-16, switched from gold-bulb-capped geared tuners), finial options, inlay program (Broinwood-style multi-strip lapis + bow-end pale panel + new hull-side inlay program), SAM-25-CONCERT chang-lineage variant, acoustic study program. Open the full file →
▶family-spec.csvCSV5-variant family table — drives the SolidWorks design-table configurationsOpen raw
▶risks.mdMDRed-team risk register with verification tests — 21 risks across structural / acoustic / supply / safety / culturalOpen
The sambuca is a single parametric SolidWorks part (MasterLayout) driven by a global-equations block. All five family variants resolve as configurations in one design table. Drawings, BOM linkage, and purchased-parts list flow from the same model.
Driving columns: body_length_mm, body_width_mm, body_depth_mm, string_count, f_min_hz, f_max_hz, string_len_max_mm, string_len_min_mm. Strings 14–25 features are always-defined and suppressed below the string count for the active config.
▶cad/SW-MIGRATION-CHECKLIST.mdMD8-step manual SW UI work after Pack-and-Go — 3–6 hrs estimatedOpen
Drawings (status: deferred until rebuild)
22-sheet manufacturing drawing package, generated as SVGs from the SolidWorks model once the MasterLayout rebuild clears. Spec lives in drawing-brief.md. Current state: placeholders only at drawings/README.md.
Purchased parts (BOM linkage)
The off-the-shelf items in the SolidWorks model link to BOM rows in the Bill of Materials section below. Key purchased items:
BOM-009 Brass collar (60 mm tall, 0.8–1.2 mm wall) — McMaster brass tube or Online Metals sheet
BOM-017 Geared tuners (compact-housing, 13 ea) — Stewart-MacDonald classical / Allied Lutherie small-format harp tuners — mock-fit before bulk order (R-X-04)
3D assets pending. Once the SolidWorks MasterLayout rebuild completes (per cad/SW-MIGRATION-CHECKLIST.md), this section will host:
Spin GIF (model/sambuca-spin.gif) — 4-second turnaround of SAM-13-ROOT for quick orientation
3D PDF (model/sambuca-3d.pdf) — interactive U3D-embedded PDF for review on any machine without SolidWorks
glTF/GLB (model/sambuca.glb) — web-renderable model for embed in the public site once the build clears the cultural-advisor gate
Export commands documented in the bake-into-skill follow-up — SolidWorks → Save As 3D PDF for the PDF, Save As STL + Blender export for glTF, screen-capture loop for the spin GIF.
Pre-bench checklist for the SAM-13-ROOT build at Maker Nexus (planned primary makerspace). Print this section + assembly-manual.md + cnc/cnc-plan.md as a single packet before stepping into the shop.
CNC inlay pocket — multi-strip lapis band + bow panel
3 mm cedar soundboard
cnc/sambuca-neck-sweep.nc
CNC sweep along neck curve, 3-axis + rotary index
laminated sapele blank
laser/sambuca-hull-inlay-master.svg
Laser-cut inlay tiles for hull-side panels (CNC pockets, laser tiles drop in)
brass + shell + dyed veneer
Raw materials summary
Full BOM lives in section 6; full sourcing list in section 7. Key shop-floor pulls:
Walnut FAS QSWO 8/4 — one billet for CNC-from-block (200×650×200 mm) or ~10 staves for stave-laminated option (BOM-001 · Bell Forest Products / Owl Hardwood, 2–4 wk lead)
Western red cedar quartersawn 3 mm — soundboard panel, 200×650 mm (BOM-004 · LMI / Stewart-MacDonald, 1–3 wk lead). Order both 2.5 and 3.0 mm thicknesses for Wolfram sweep validation.
Sapele quartersawn 8/4 — neck stock, ripped to three 12 mm laminates (BOM-008 · Bell Forest / Owl Hardwood / LMI, 2–4 wk lead)
Lapis-look dyed veneer set — 5 strips × 1.5 mm + holly/maple spacers (BOM-011 · Certainly Wood / Veneer Supplies, 2–4 wk lead). Two-supplier sample compare per R-X-01.
Mother-of-pearl / shell composite panel — 100×60 mm for bow-end inlay (BOM-007 · Stewart-MacDonald / LMI / Maples Inlays, 1–3 wk lead). Three-candidate sample compare per R-X-02.
Brass collar stock — 60 mm tall, 0.8–1.2 mm wall tube or sheet (BOM-009 · McMaster-Carr / Online Metals, 1 wk lead)
Geared tuners + PVD bulb caps — 13 each (BOM-017 / BOM-018 · highest-risk supply items, place orders first)
08 · Cut listRough → final dimensions · both hull options
Hull option flag: A_block = CNC-from-block (single billet, wasteful, single-setup, cleaner for capstone schedule) · B_staves = stave-laminated (10 staves around a buck, less wood total, +2–3 days glue-up). Family-scaling deltas in CUT-101 through CUT-106.
▶cut-list.csvCSV28 main rows + 6 family-scaling deltas + 5 fixtures/jigs/templates · both hull optionsOpen raw
40 verification checks across 8 categories. The gate_block column flags the four checks that gate public release. Each row links back to a row in the risk register (linked_risk).
The CNC operation plan is a pre-CAM document: it specifies setups, workholding, tool selection, feeds and speeds, and the sequence of operations per part, but does not generate G-code. CAM (Fusion 360 / VCarve) handles that downstream from the SolidWorks rebuild.
Full CNC plan document at cnc/cnc-plan.md. Operations sequenced as: (1) Hull billet rough — 1/4″ upcut, full-billet stock removal, vacuum chuck + machinable fixture. (2) Hull hollow — 1/8″ finishing pass, wall thickness from hull_wall_mm = 6. (3) Hull-side inlay pockets — same setup as hull rough; 3-axis with rotary indexing for the two longitudinal panels. (4) Neck sweep — laminated blank in custom curved fixture; 3-axis with rotary. (5) Soundboard inlay — separate setup, rule-bar fence, 0.8–1.0 mm end mill for multi-strip lapis band + 100×60 mm bow panel pocket + Heifer Zephyr wordmark pocket if Option A locks. Brass collar work happens after neck-body joint cures.
Four-stage coupled acoustic model in Wolfram Language. Each stage is modeled separately; the combined response is the key output that voices the family.
Stage 1 · String
f = (1/2L)·√(T/μ)Per-string tension and length at G-major tuning
Stage 2 · Cavity
~143 Hz keel portHelmholtz prediction for SAM-13-ROOT geometry
Stage 3 · Plate
Cantilever / ChladniFirst plate mode in lower-middle string range
Section 11 — Sensitivity analysis (which parameters move which output the most)
Open in Wolfram Cloud or Mathematica desktop. Sweep plan: soundboard species × thickness × keel-port geometry across the three family variants. Validation: confirm the 143 Hz keel-port Helmholtz prediction with a measured impulse-response on the SAM-13-MULE (per V-A-04).
Run it — Wolfram Cloud embed
Once wolfram-cloud-sync uploads this notebook and sets public-execute permission, this block renders an interactive embed where you can change parameters (soundboard species, port geometry, family variant) and see the coupled-response plots update live — no Mathematica install required.
How the embed gets activated
Run wolfram-cloud-sync's upload pass — pushes sambuca-acoustics-starter.wl to CloudObject["GitHub-Inbox/sambuca__wolfram__sambuca-acoustics-starter.wl"]
In a Wolfram Cloud notebook, run SetPermissions[CloudObject["GitHub-Inbox/sambuca__wolfram__sambuca-acoustics-starter.wl"], "Public" -> "Execute"] to allow anonymous viewers to interact with the notebook
Run EmbedCode[CloudObject["GitHub-Inbox/sambuca__wolfram__sambuca-acoustics-starter.wl"]] to get the official embed snippet — copy the iframe URL it produces
Paste that URL into the data-cloud-url attribute above (and into engineering.wolfram.cloud_url in capstone-manifest.json once that schema field lands in the instrument-maker-v4 bake-in step)
Note: this is the one section that breaks "offline-first" — the iframe loads from wolframcloud.com. When the URL is PENDING the embed stays dormant and no external request is made, so the explorer is still fully offline-capable for the static content.
12 · Risk register21 risks · 3 release-blocking
Red-team pass on the SAM-13-ROOT build target and the four sibling variants. Every risk has a verification test attached (linked to validation.csv). Public-release-blocking: R-S-01 (neck cantilever) · R-S-05 (SAM-25 harness eyebolt) · R-C-01 (cultural-advisor review).
▶risks.mdMDStructural · acoustic · ergonomic · supply · fit/finish · safety · cultural — full registerOpen
13 · Capstone deliverablesDeck · print packet · explorer
Three primary deliverables for the Fall 2026 capstone window plus this explorer.
Pending tuning lock on SAM-13-MULE. The learn-to-play/ folder is populated by the sheet-music skill once the MULE voicing pass locks G-major (G3 → E5) on the build target. Once unlocked, this section will host:
Woolley, C. L. (1934).Ur Excavations, Vol. II: The Royal Cemetery. British Museum / University of Pennsylvania Museum joint publication
Kora MasterLayout parametric template — Tony Koop, prior work at GitHub/kora
License
Dual-license by content type. Design files (cad/, drawings/, cnc/, harness/, BOM/sourcing/cut-list/validation/family-spec CSVs, wolfram .wl) under CERN-OHL-W-2.0. Written content and media (.md docs, capstone deck, print-packet.*, site/, images/, learn-to-play/) under CC-BY-4.0. See LICENSE for the overview.
