Great Highland Bagpipe Build Packet

What this is

(section missing in design.md)

The design

The Great Highland Bagpipe is a coupled reed/resonator/reservoir system. The packet intentionally uses different first-order models for different subsystems, then validates the coupled result under pressure.

Chanter

The chanter is a conical bore driven by a double reed. A conical reed pipe behaves closer to an open-open pipe for pitch than a cylindrical stopped pipe, but tone holes, reed compliance, and bore taper dominate the final intonation. The workbook dimensions and measured practice-chanter hole positions are the starting geometry.

```text f_chanter ~= c / (2 * L_eff) L_eff ~= c / (2 * f_target) c = speed of sound in inches per second ```

Worked example from the workbook:

```text Low A = 480 Hz c = 13510 in/s L_eff = 13510 / (2 * 480) = 14.073 in Workbook physical full chanter length = 14.5 in ```

The difference between effective and physical length is expected because the reed seat, conical end behavior, bell flare, and tone-hole network all shift the effective acoustic length. Final tuning must start with undersize holes and open them by measurement.

Drones

The drones are cylindrical single-reed pipes, closed at the reed end and open at the top. They are first-pass stopped pipes with odd-harmonic emphasis.

```text f_drone ~= c / (4 * L_eff) L_eff ~= c / (4 * f_target) ```

Worked examples from the workbook:

```text Tenor drone A3 = 240 Hz L_eff = 13510 / (4 * 240) = 14.073 in

Bass drone A2 = 120 Hz L_eff = 13510 / (4 * 120) = 28.146 in ```

The workbook's physical sections intentionally exceed or subdivide these effective lengths because tuning chambers, hemped slides, reed seats, and cap geometry move the acoustic endpoint.

Bag Pressure And Reeds

The bag is a pressure reservoir, not just a container. The reed only oscillates inside a stable pressure window. Pressure changes can sharpen or destabilize the chanter and drones, so every tuning row in `validation.csv` includes environment and pressure notes.

```text cents_error = 1200 * log2(measured_hz / target_hz) pressure_target = 18-25 inH2O for first prototype testing ```

Empirical Correction Guard

No Native American flute K2 correction is applied here. This packet uses first-order conical/stopped-pipe estimates plus measured GHB-specific validation rows. Any future correction must be derived from measured chanter, drone, reed, and pressure data from this family.

The build

Great Highland Bagpipe Assembly Manual

Shop Principle

Do not build the ornate final set first. Bagpipes are a pressure-coupled reed system; a beautiful bore that cannot be tuned with the chosen reeds is scrap. Retire reed, pressure, and leakage risk before committing expensive blackwood.

Tools And Fixtures

• Lathe with chuck/collet support, tailstock drill chuck, live center, and
• Step-drill set, long bits, reamers, bore gauges, and a purpose-made chanter
• V-block or indexed drill fixture for chanter tone holes.
• Manometer for bag pressure.
• Calipers, small bore gauges, tuner, tape, beeswax, waxed hemp, and leak-test
• Reed-seat and tenon/socket gauges turned from stable offcuts.

Phase 0 - Buy The Coupling Parts

1. Buy at least three commercial chanter reeds before finalizing the reed seat. 2. Buy a synthetic drone reed set. 3. Buy or borrow a synthetic zipper bag and a blowpipe valve. 4. Measure reed body/staple diameters and update `validation.csv`.

Phase 1 - Prototype Chanter

1. Rough-turn the blank oversized and leave holding allowance at both ends. 2. Establish the bore datum from the reed seat end. 3. Step-drill conservatively, then ream to the planned taper. 4. Turn the exterior only after the bore is confirmed straight enough. 5. Drill tone holes undersize using the datum plan in `drawing-brief.md`. 6. Fit a commercial reed and check Low A at stable pressure. 7. Use tape and incremental enlargement to bring the scale into range.

Phase 2 - Tenor Drone Proof

1. Build one tenor drone bottom and top. 2. Bore the bottom and top to the workbook dimensions. 3. Turn the tuning slide with planned hemp clearance. 4. Fit a tenor drone reed and find the slide range for A3. 5. Log reed setting, pressure, temperature, and cents error. 6. Duplicate the validated tenor.

Phase 3 - Bass Drone

1. Build the bass bottom, middle, and top as separate sections. 2. Use a steady rest and center-drill strategy for the long middle section. 3. Bore slightly conservatively where reaming or sanding is planned. 4. Fit the bass drone reed and confirm A2 with usable tuning travel.

Phase 4 - Stocks, Bag, And Blowpipe

1. Batch-turn five stocks with tie-in grooves. 2. Turn the blowpipe body and fit the one-way valve. 3. Tie the stocks into the synthetic bag. 4. Leak-test each stock before inserting reeds or drones. 5. Assemble all pipes with hemped joints and repeat the leak test.

Phase 5 - Tuning And Balancing

1. Tune both tenors together at stable pressure. 2. Add the bass drone and tune it against the tenors. 3. Add the chanter and tune Low A against the drone reference. 4. Work upward through the chanter notes, changing one variable at a time. 5. If pressure changes shift multiple notes together, correct pressure/reed behavior before changing hole geometry.

Maintenance Loop

• Before each session: inspect reeds, check hemped joints, confirm blowpipe
• After each session: dry moisture from blowpipe and stocks, inspect reed
• Weekly during prototype: repeat drone tuning and bag leak validation.
• After 24 hours: recheck pitch because hemp compression can change slide

Stop Conditions

Stop and redesign or rebuild the affected part if any of these occur:

• Chanter bore wander is visible or pitch errors cannot be corrected with hole
• A stock tie-in leaks after two attempts.
• A tuning slide binds before reaching target pitch.
• A reed only speaks outside the expected pressure range.
• Any crack appears around a bore, stock groove, or slide socket.

No process photos in images/. Add at least one to populate this section.

The numbers

BOM

Cut list

Tuning & validation

Known risks

Risks - Great Highland Bagpipe

Acoustic Chanter Bore And Reed Do Not Agree

**Symptom:** Low A speaks, but the chanter scale cannot be brought into tune by normal tape and hole enlargement.

**Mechanism:** The conical bore, reed compliance, tone-hole network, and bag pressure form a coupled system. A first-order `c/(2L)` estimate does not capture the full behavior.

**Test:** Build the prototype chanter in low-cost material, record every note at stable pressure, and compare cents error against `validation.csv`.

**Mitigation:** Keep holes undersize, test with multiple commercial reeds, and adjust bore/hole plan before using blackwood.

**Severity:** High - human decision required before final-material chanter.

Structural Long Bore Wanders Or Cracks

**Symptom:** Chanter or bass middle section shows off-center bore, thin wall, or cracking during reaming/turning.

**Mechanism:** Long small-diameter bores in dense wood create heat, tool wander, and hoop stress. Blackwood is hard and expensive but not forgiving.

**Test:** Bore and ream a prototype blank, then measure wall thickness at both ends and inspect for heat checking.

**Mitigation:** Use headstock-supported drilling, clear chips often, prototype in Delrin/ipe/cherry first, and reject blanks with runout or checks.

**Severity:** High - human decision required before final-material bore work.

Ergonomic Pressure And Reach Fatigue

**Symptom:** The set can be tuned on the bench but is tiring or unstable during real playing.

**Mechanism:** Bag size, blowpipe length, stock placement, chanter hand spacing, and reed strength interact with player posture and arm pressure.

**Test:** Run a timed 10-minute playing simulation with manometer readings and note any hand stretch, neck/arm fatigue, or pressure instability.

**Mitigation:** Start with a known synthetic bag size, use medium reeds, keep the practice chanter step, and adjust blowpipe/stock ergonomics before final decoration.

**Severity:** Medium.

Supply Reed Or Bag Substitution Changes The Whole System

**Symptom:** A substitute reed or bag part fits mechanically but changes pitch, pressure threshold, or stock layout.

**Mechanism:** Reed body/staple dimensions and bag stock-hole positions are not universal across makers. The acoustic and mechanical interface can shift.

**Test:** Measure purchased reed bodies, staple OD, bag stock layout, and valve fit before cutting reed seats or tying in stocks.

**Mitigation:** Buy coupling parts first, update drawings from measured parts, and keep supplier substitutions out of final dimensions until measured.

**Severity:** Medium.

Fit/Finish Decorative Mounts Lock In Before Tuning Is Stable

**Symptom:** Ferrules, imitation ivory mounts, or engraving prevent later slide, stock, or bore corrections.

**Mechanism:** Decorative parts can hide joints, limit slide travel, or make a prototype feel "finished" before acoustic validation is done.

**Test:** Assemble and tune the plain prototype for 24 hours before installing permanent decorative parts.

**Mitigation:** Make mounts removable in prototype, omit engraving until the validation report is clean, and keep slide access visible.

**Severity:** Low.

Family overview

• GHB-CHANTER — Low A
• GHB-TENOR-1 — A3
• GHB-TENOR-2 — A3
• GHB-BASS — A2
• GHB-BLOWPIPE — pressure supply
• GHB-STOCKS — airtight fit

Resources

• Project README
• Capstone deck (.pptx)
• Printable shop packet (.pdf)
• Tony's GitHub