Project: Shakuhachi (SHK-D4-P1)
Date: 2026-05-07
Driver: Tony Koop
Skill: instrument-maker-v4
A single-instrument build packet for SHK-D4-P1 — a 1.8-shaku D4 solid-cherry shakuhachi prototype. Open-pipe acoustics; bore drilled with the headstock-driven deep-bore drilling technique on the lathe. Hand-cut utaguchi. Five tone holes (4 front + 1 thumb), tuned to Kinko-ryū intervals.
| Step | Operation | Time | Page |
|---|---|---|---|
| 1 | Mill blanks (1×1×24 cherry) | 30 min | §B |
| 2 | Build tailstock vise (1-time) | 90 min | §C |
| 3 | Pine-scrap validation pass | 45 min | §D |
| 4 | Production deep-bore | 90 min | §D |
| 5 | Outside turn between centers | 60 min | §E |
| 6 | Tone-hole layout + drill 7 mm | 45 min | §F |
| 7 | Cut + file utaguchi | 60 min | §G |
| 8 | Bisque-style tuning | 90 min | §H |
| 9 | Walnut-oil + cure | 5 d | §I |
| 10 | Carnauba wax + final pass | 30 min | §I |
Solid-billet hardwood adaptation of the shakuhachi. Western luthier shop. 1.8-shaku D4 first; sized siblings later. Document the open-pipe acoustic model honestly so the first measurement drives a corrections database update. Not a tradition-faithful reproduction; respectful of Kinko-ryū / Tozan-ryū lineage.
(extract — full table in bom.csv)
| ID | Item | Qty | Cost (USD) |
|---|---|---|---|
| SHK-BOM-001 | Cherry blanks 1×1×24 in | 3 | 28.00 |
| SHK-BOM-003 | 3/8 in pilot brad-point bit | 1 | 16.00 |
| SHK-BOM-004 | Step-up drill set 1/2-3/4 in | 1 | 42.00 |
| SHK-BOM-005 | 20 mm reamer 24 in OAL | 1 | 68.00 |
| SHK-BOM-006 | Tailstock vise (build) | 1 | 35.00 |
| SHK-BOM-007 | Tone-hole drill jig (build) | 1 | 15.00 |
| SHK-BOM-008 | Diamond files round + flat | 1 | 22.00 |
| SHK-BOM-010 | Korg OT-120 chromatic tuner | 1 | 89.00 |
| SHK-BOM-013 | Walnut oil 8 oz | 1 | 14.00 |
| SHK-BOM-014 | Carnauba wax 4 oz | 1 | 11.00 |
Total pictured: ~430 USD excluding optional inlay block.
Primary: Bell Forest Products (cherry), Travers Tool (reamer), Lee Valley (bits + files), Sweetwater (tuner), Tried & True (walnut oil), McMaster-Carr (vise hardware).
Long-lead item: 20 mm reamer (~10 days). Order first.
(full table in cut-list.csv)
| Cut ID | Part | Operation |
|---|---|---|
| SHK-CUT-001 | Cherry blank | Headstock-driven deep-bore + turn between centers |
| SHK-CUT-002 | Foot end face | Lathe parting + sandpaper face |
| SHK-CUT-003 | Utaguchi notch | Bandsaw + chisel + file (32° inner bevel) |
| SHK-CUT-004…008 | Tone holes | Drill press w/ V-cradle jig; 7 mm brad-point undersize |
| Drawing | Shows | Scale |
|---|---|---|
| SHK-D4-P1-overall.svg | Side elevation, full body, hole positions | 1:2 |
| SHK-D4-P1-bore-section.svg | Section A-A through bore axis | 1:2 |
| SHK-D4-P1-utaguchi.svg | Utaguchi notch geometry, 32° bevel | 4:1 |
| SHK-D4-P1-hole-layout.svg | Unwrapped cylinder paper-wrap template | 1:1 |
| SHK-D4-P1-blank.svg | Pre-bore square stock | 1:4 |
| SHK-fixture-vise.svg | Tailstock vise welded fixture | 1:2 |
| SHK-fixture-hole-jig.svg | Tone-hole drill-press V-cradle jig | 1:2 |
See assembly-manual.md for the full 13-step shop manual. The steps are:
1. Read first (design.md, risks.md, instrument-maker#84)
2. Mill blanks
3. Center-mark + cross-mark
4. Build tailstock vise (one-time)
5. Scrap-stock validation pass (mandatory)
6. Production deep-bore (the long one)
7. Outside turn
8. Tone-hole layout + drill undersize
9. Cut utaguchi
10. Bisque-style tuning (post-utaguchi)
11. Per-hole tuning
12. Octave check
13. Finish + record
(blanks for shop notes — see validation.csv for the full row set)
| Stage | Target | Measured | Pass / Fail | Notes |
|---|---|---|---|---|
| Bore wander @ 6 in | < 0.020 in | _____ | □ | |
| Bore wander @ 12 in | < 0.040 in | _____ | □ | |
| Bore wander @ 18 in | < 0.080 in | _____ | □ | |
| Bore ID @ foot | 0.787 ± 0.003 | _____ | □ | |
| Bore ID @ mid | 0.787 ± 0.005 | _____ | □ | |
| Bore ID @ top | 0.787 ± 0.005 | _____ | □ | |
| Wall @ hole-4 station | ≥ 0.150 in (any quadrant) | _____ | □ | |
| Ro fundamental | 293.665 Hz ± 25 ¢ (pre-tune) | _____ | □ | |
| Ro fundamental | 293.665 Hz ± 10 ¢ (post-tune) | _____ | □ | |
| Tsu (F4) | 349.228 Hz ± 10 ¢ | _____ | □ | |
| Re (G4) | 391.995 Hz ± 10 ¢ | _____ | □ | |
| Chi (A4) | 440.000 Hz ± 10 ¢ | _____ | □ | |
| Ri (C5) | 523.251 Hz ± 10 ¢ | _____ | □ | |
| Thumb (D5) | 587.330 Hz ± 10 ¢ | _____ | □ | |
| Octave Ro → Ro′ | 587.330 Hz ± 25 ¢ | _____ | □ | |
| 30-day drift | < 5 cents at 68 °F | _____ | □ |
Environment row (mandatory): Temp ____°F · RH ____% · tuner ____ · player ____
See supplier-rfq.md for the full RFQ. Headlines: 3 quarter-sawn cherry blanks, 20 mm reamer at 24 in OAL, deep-bore drill set, validation hardware, oil + wax finish supplies, hardware for fixtures.
A single-sheet (A3 landscape) plate with hero photo + tooling thumbnails + cost summary. See visual-bom-brief.md for the layout spec.