The siku (Aymara: siku') is a panpipe from the Andean Altiplano, with documented use among Aymara and Quechua peoples of Bolivia and Peru. Archaeological specimens found at Tiwanaku and Nazca sites date the instrument to at least 1500 BCE. It remains a living instrument in Aymara communities today.
What makes the siku distinctive is yanantin — the Aymara philosophy of complementary pairing. A siku is not played alone. The instrument is split into two interlocking ranks: arka (the leader, seven tubes) and ira (the follower, six tubes). Together they form a complete Mixolydian scale, but neither rank contains it alone. Two players interlock their notes in call-and-response, weaving a single melody from two halves. The music enacts a cultural value — a whole that neither part can express alone.
Four size classes follow the traditional Andean ensemble hierarchy — bass (Toyo), tenor (Zanka), alto (Malta), soprano (Chili). Each is a complete interlocking siku. The primary build target in this packet is the Zanka (key of C, bore ⌀0.625").
The 13 Zanka tubes span G3–E5 in a Mixolydian scale. Arka rank (7 tubes) carries the odd-numbered positions; Ira rank (6 tubes) carries the even-numbered positions.
| Tube ID | Rank | Note | Hz | L_calc (in) | L_cut (in) |
|---|---|---|---|---|---|
| Z-A1 | Arka | G3 | 196.00 | 16.961 | 17.148 |
| Z-I1 | Ira | A3 | 220.00 | 15.076 | 15.264 |
| Z-A2 | Arka | B3 | 246.94 | 13.395 | 13.582 |
| Z-I2 | Ira | C4 | 261.63 | 12.620 | 12.807 |
| Z-A3 | Arka | D4 | 293.66 | 11.157 | 11.344 |
| Z-I3 | Ira | E4 | 329.63 | 9.878 | 10.065 |
| Z-A4 | Arka | F4 | 349.23 | 9.292 | 9.479 |
| Z-I4 | Ira | G4 | 392.00 | 8.231 | 8.418 |
| Z-A5 | Arka | A4 | 440.00 | 7.188 | 7.375 |
| Z-I5 | Ira | B4 | 493.88 | 6.447 | 6.635 |
| Z-A6 | Arka | C5 | 523.25 | 6.060 | 6.247 |
| Z-I6 | Ira | D5 | 587.33 | 5.328 | 5.516 |
| Z-A7 | Arka | E5 | 659.26 | 4.627 | 4.814 |
Formula: L_calc = 13552 / (4 × f_hz) − 0.82 × 0.625 · L_cut = L_calc + 3/16" trim allowance · Stopped pipe; odd harmonics only.
The siku is a stopped cylindrical pipe: one end open (the blow end), one end closed (beeswax plug or natural bamboo node). Stopped pipes produce only odd harmonics — 1f, 3f, 5f — giving the siku its characteristic hollow, fundamental-rich timbre.
| Parameter | Value | Notes |
|---|---|---|
| Speed of sound | 13,552 in/s | At 68°F shop standard (c = 1129.3 ft/s) |
| End correction coefficient | 0.82 × bore_ID | Empirical; bundles embouchure effects. Standard physics value is 0.3×d. |
| Tube length formula | L = c/(4f) − 0.82×d | Physical length for target frequency f (Hz) |
| Trim allowance | +3/16" (0.1875") | All L_cut values include this margin for pitch adjustment |
| Harmonic series | 1f, 3f, 5f… | Odd harmonics only (stopped pipe) |
| Tuning target | A4 = 440 Hz | Equal temperament |
validation.csv (VAL-BORE rows)cnc/setup-sheet.md §6cut-list.csvrisks.md AC-04cnc/setup-sheet.md §5validation.csvcnc/setup-sheet.md §1cnc/setup-sheet.md §7validation.csvphoto-shotlist.mdFull BOM in bom.csv · Sourcing guide in sourcing.csv
| Category | Item | Qty | Est. Cost | Primary Source |
|---|---|---|---|---|
| Tubes | Bamboo cañahueca, ⌀0.821" OD × 18" sticks | 16 sticks | $18–30 | Etsy / bamboo flute suppliers |
| Tubes (alt) | PVC Sch40 conduit, 1/2" nominal | 8 ft | $6–8 | Home Depot / local hardware |
| Frame | Cherry S4S, 3/4" × 1-1/2" × 14" | 4 pcs | $12–16 | Local hardwood dealer |
| Sealing | Beeswax block, raw | 4 oz | $4–8 | Beekeeping supply / Amazon |
| Binding | Waxed linen cord, 1mm | 50 ft | $4–6 | Bookbinding supply |
| Finish | Danish oil, 1 pint | 1 | $10–14 | Woodcraft / local |
| Tools | Chromatic tuner (clip or app) | 1 | $12–30 | Guitar Center / GuitarTuna app (free) |
Photos pending. See photo-shotlist.md for the full 36-shot list. Shoot on neutral grey or linen background; include ruler for scale in at least one shot per group.
| Drawing | File | Description |
|---|---|---|
| Tube Cross-Section | siku-tube-section.svg | All 4 bore/OD/wall profiles side by side |
| Zanka Elevation | siku-zanka-elevation.svg | 13-tube elevation with arka/ira split, lengths, Hz |
| Family Overview | siku-family-overview.svg | 4-member side-by-side silhouette comparison |
| Toyo Elevation | siku-toyo-elevation.svg | Bass member, 13 tubes |
| Malta Elevation | siku-malta-elevation.svg | Alto member, 13 tubes |
| Chili Elevation | siku-chili-elevation.svg | Soprano member, 13 tubes |
| Frame Rail Detail | siku-frame-rail-detail.svg | Pocket dimensions and spacing (Zanka) |
| Sealing Stand | siku-sealing-stand.svg | Plywood stand drill pattern |
| Wax Plug Detail | siku-wax-plug-detail.svg | Plug depth, stopped-end cross-section |
| Story Stick | siku-story-stick.svg | Zanka story stick layout with all 13 marks |
| File | Type | Description |
|---|---|---|
| design.md | Design | Governing model, provenance, tube length tables, physics |
| family-spec.csv | Data | 4-row table with all tube parameters per member |
| bom.csv | Data | Full bill of materials — all 4 members + shared items |
| sourcing.csv | Data | Supplier options with substitute risk notes |
| cut-list.csv | Data | 52 tube cuts + 4 rail cuts with notes |
| validation.csv | Data | Per-tube validation with target Hz, tolerance |
| assembly-manual.md | Manual | 8-phase build manual with tool list and safety notes |
| risks.md | Risk | 11 structured risks with verification tests |
| jig-decision.md | Decision | Fixture selection for each manufacturing operation |
| cnc/setup-sheet.md | CNC | Machine setup, datums, tooling, release checks |
| cnc/operations.csv | CNC | Machine-readable operation list with all parameters |
| wolfram/instrument-model.wl | Model | Interactive Wolfram tube-length explorer and spectrum analyzer |
| resources.md | Reference | Acoustic, ethnomusicological, and maker references |
| photo-shotlist.md | Photo | 36-shot photo list for build log and portfolio |
| supplier-rfq.md | Sourcing | RFQ templates for bamboo, PVC, cherry, cord/wax |
| siku-zampona-design-table.xlsx | Spreadsheet | Master design table — all 4 members, all parameters |
