Slip-Cast Ceramic Ocarina (OCA-001) — v3.1 smoke test Print Packet

Generated: 2026-05-02

Packet folder: `C:\Users\Tony\Documents\GitHub\ocarina`

File Map

design.md

Project intent, catalog metadata, assumptions, and validation plan.

Ocarina Build Packet

Source

• Design table: `docs/Ocarina.xlsx`
• Sheet: `Ocarina`
• Inspected range: `A1:H141`
• Workbook content observed: design inputs, size library, Helmholtz calculator, 12-hole fingering chart, ceramic workflow, BOM, design notes, and Wolfram notebook notes.

Design Intent

Build a slip-cast ceramic Alto C 12-hole ocarina using a 3D-printed master and plaster mold workflow. The current table is focused on the standard "sweet potato" vessel-flute form, but the same model can be used as the baseline for sculptural vessel flutes.

Governing Model

Ocarinas behave primarily as Helmholtz resonators:

f = c/(2*pi) * sqrt(A_open/(V_chamber * L_eff))

Unlike a transverse flute or Native American style flute, pitch is driven by chamber volume and total open-hole area, not tone-hole distance along a bore. Hole position is still important for ergonomics, grip, and fingering logic.

Current Workbook Inputs

Critical Design Features

• Chamber volume is the master tuning input. Measure it by water fill after CAD, master print, greenware, bisque, and glaze fire.
• Voicing window area sets the all-closed low-note behavior along with volume and effective neck length.
• Fipple geometry is the playability bottleneck: windway gap, labium angle, channel smoothness, and edge sharpness should be treated as first-class dimensions.
• Finger holes should start undersized. Enlarge to sharpen; flattening after over-enlarging is possible but slower and less clean.
• Exterior-only glazing is preferred for tuning stability and acoustic response. Mask the fipple, holes, and chamber interior.

Workbook Improvement Notes

During inspection, rows 39-42 of the 12-hole fingering chart contain formulas for hole area, cumulative open area, and calculated frequency. Rows 43-51 currently show placeholder `=` cells instead of filled formulas. Recommended next workbook cleanup:

1. Copy the area formula pattern from `D40:D42` through `D51`.

2. Copy the cumulative area pattern from `E40:E42` through `E51`.

3. Copy the frequency formula pattern from `F40:F42` through `F51`.

4. Add measured frequency, cents error, and tuning action columns.

5. Add a note that hole combinations can be cross-fingered if total open area is equivalent.

6. Verify the size-library `Length (in)` column. Inspection showed serial-like values such as `46180`, so those cells may have been formatted or entered incorrectly.

Mold Strategy

Use a 2-piece plaster mold for the main body. The first prototype can use a press-molded body to speed iteration, but production should move toward slip casting once the fipple and chamber volume are stable.

Recommended mold/CAD features:

• Split line around the widest body perimeter.
• Positive registration keys that do not trap clay.
• Pour/drain path or assembly opening appropriate to the chosen casting workflow.
• Removable or cleanable fipple detail. If the fipple is too delicate for the mold, cast a blank and hand-cut the voicing at leather-hard stage.
• Master scale factor: `1/(1 - shrinkage)`; for 12 percent shrinkage this is about `1.136`.

Prototype Ladder

Open Assumptions

• Pricing in the workbook is an estimate and has not been date-checked.
• Clay shrinkage must be measured for Tony's actual slip, not assumed from supplier average.
• The fipple may need empirical iteration beyond the Helmholtz model.
• Exact ergonomics depend on hand span and final sculptural body shape.

bom.csv

Starter bill of materials with part categories, quantities, drawing refs, and notes.

sourcing.csv

Supplier/search tracker with specs, price/date fields, lead time, substitutes, and risks.

cut-list.csv

Rough/final stock sizes, material, grain/orientation, operations, yield, and offcuts.

drawing-brief.md

Manufacturing drawing and technical product sketch brief.

Ocarina Drawing Brief

Required Views

• Top view with body outline, hole layout, hand assignment, and centerline.
• Side view with mouthpiece axis, windway height, labium angle, body thickness, and split line.
• Section through fipple showing windway, labium, window, and chamber connection.
• Section through body showing chamber volume reference, target wall thickness, and mold split.
• Detail view for hole diameters and post-fire tuning allowance.
• Mold view showing plaster parting line, registration keys, pour/drain plan, and cottle clearance.

Critical Dimensions

Notes For CAD

• Store chamber volume as a named parameter.
• Store shrinkage factor as a named parameter.
• Separate final fired dimensions from master dimensions.
• Mark fipple geometry as prototype-sensitive; do not freeze it until test pieces speak reliably.
• Include a versioned body ID so castings can be tied back to the CAD master.

assembly-manual.md

Shop-facing sequence, tools, fixtures, safety, tuning, finishing, and maintenance notes.

Ocarina Assembly Manual

Scope

This manual covers a slip-cast or press-molded ceramic ocarina based on `docs/Ocarina.xlsx`. It is written for prototype builds where the first goal is repeatable tone and validated tuning, not decorative finish.

Tools

• CAD package for master design.
• 3D printer and sanding/sealing supplies.
• Cottle boards, plaster mixing bucket, scale, mold soap, and clamps.
• Stoneware slip or workable clay body.
• Small hole cutters, drill bits, needle tools, loop tools, ribs, sponge, and fettling knife.
• Chromatic tuner, microphone, calipers, graduated syringe or water-fill vessel.
• Diamond needle files or fine diamond burrs.
• Wax resist, glaze, and kiln access.

Process

1. **Set design inputs**

- Confirm target ocarina size, chamber volume, voicing window, wall thickness, clay body, and shrinkage.

- Create a build ID before CAD begins.

2. **Model the master**

- Model the body as a controlled-volume vessel.

- Include split-line planning, registration features, and a fipple strategy.

- Scale the master by `1/(1 - measured_shrinkage)`.

3. **Print and finish the master**

- Print the master with enough wall strength to survive mold making.

- Sand layer lines and seal the surface.

- Mark datums: centerline, mouthpiece axis, split plane, and hole reference side.

4. **Make the mold**

- Apply release to the sealed master and cottle surfaces.

- Pour plaster with at least 1.5 inches around the master where practical.

- Add registration keys and dry the mold fully before casting.

5. **Cast or press the body**

- For slip casting, pour slip, wait for target wall buildup, drain, and demold at leather-hard stage.

- For press molding, press even clay slabs into both mold halves and join with scored slip.

- Measure sample wall thickness at a noncritical trimmed area.

6. **Cut fipple and holes**

- Establish the windway first.

- Cut the labium cleanly and test blow before the body fully dries.

- Cut finger holes undersized.

7. **Dry slowly**

- Dry under plastic until moisture equalizes.

- Watch the mouthpiece and seam areas for cracks.

8. **Bisque fire**

- Bisque to the clay body's recommended schedule.

- Measure mass, volume, hole diameters, and frequencies.

9. **Tune after bisque**

- Enlarge holes to raise pitch.

- Refine the fipple only in small steps.

- Record measured frequency and cents error after each change.

10. **Glaze**

- Wax resist the windway, labium, holes, and any interior opening.

- Keep glaze away from the acoustic edges.

11. **Final fire and validation**

- Fire to the chosen glaze schedule.

- Re-measure all tuning points.

- Save final dimensions and tuning data back into the validation log.

Failure Modes To Watch

• Weak or no tone: windway too tall, labium too blunt, air jet missing edge.
• Pitch too flat: chamber too large, open area too small, or neck length too long.
• Pitch too sharp: chamber too small, open area too large, or over-filed holes.
• Warped mouthpiece: uneven drying or thin unsupported fipple geometry.
• Glaze-choked note: glaze reduced hole or windway opening.

validation.csv

Target/measured values, tolerance, environment, result, and tuning/build action log.

supplier-rfq.md

Supplier email/request-for-quote starter.

Supplier RFQ — Slip-Cast Ceramic Ocarina (OCA-001 family)

> Use this as a template for outreach to ceramic-supply, plaster, mold-making, and finishing suppliers. Customize the Subject and address fields per recipient.

**Subject:** RFQ — slip-cast ceramic ocarina prototype materials and consumables

Hello,

I'm a mechanical R&D engineer prototyping a small family of slip-cast ceramic ocarinas (vessel flutes, ~3-4 in long, ~0.16 in / 4 mm wall) and need quotes for the following. The first build is an Alto C 12-hole prototype based on the parametric Helmholtz design table at [tonykoop/ocarina](https://github.com/tonykoop/ocarina).

Items

|---|---|---|---|

What we need in your quote

• **Unit price** and any volume breaks
• **Minimum order quantity**
• **Current stock status** and **lead time**
• **Shipping estimate** to 94566 (Pleasanton, CA) — or local pickup option
• **Material safety data sheet (MSDS)** and **technical data sheet** for items 1, 2, 4, 5
• **Recommended substitutions** for thin-walled (~4 mm) musical instrument bodies
• For item 1: most recent **shrinkage test data** for your batch (we will re-measure on our side, but a baseline matters)

Acceptance criteria

The prototypes are measured for X/Y/Z shrinkage, bore/cavity volume after firing, wall-thickness consistency, and acoustic tuning (chromatic tuner, ±25 cents target post-bisque). Slip with unknown or wildly variable shrinkage invalidates the master scale factor (currently `1/(1-0.12) = 1.136`), so reproducibility data is more valuable than headline price.

The repo is a private R&D portfolio repo; we do not need any IP-restricted documents. Public-domain MSDS and supplier spec sheets are sufficient.

Thank you,

Tony Koop

Mechanical R&D Engineer

tonykoop@gmail.com

github.com/tonykoop/ocarina (private; access on request)

visual-bom-brief.md

Art direction for an image-forward visual BOM.

Ocarina Visual BOM Brief

Goal

Create a one-page visual BOM that helps a builder understand the ceramic ocarina workflow from digital master to tuned fired instrument.

Layout

• Header: "Slip-Cast Ceramic Ocarina - Alto C Prototype".
• Hero image: finished ocarina or clean CAD render.
• Process strip: CAD master, 3D print, plaster mold, greenware, bisque, tuning, glaze fire.
• BOM table: item number, part/material, quantity, spec, estimated cost, make/buy, image.
• Callout inset: fipple section with windway, labium, and voicing window labels.
• Validation inset: chamber volume, all-closed note, highest tested note, cents error.

Image Requirements

Use real shop photos when available. Generated or rendered placeholders should be labeled as placeholders until replaced with:

• Master print photo.
• Plaster mold photo.
• Greenware body photo.
• Fipple close-up.
• Final fired instrument.
• Tuning tool/photo of measurement setup.

wolfram-starter.wl

Wolfram starter for physics, optimization, visualization, and validation.

(* Ocarina Helmholtz notebook starter *)

ClearAll["Global`*"];

c = 34300; (* cm/s at about 20 C *)
targetA4 = 440;
volumeCm3 = 130;
wallCm = 0.4;
windowWcm = 0.9;
windowHcm = 0.5;

voicingAreaCm2[w_, h_] := w*h;
endCorrectionCm[area_] := 0.6*Sqrt[area/Pi];
helmholtzHz[area_, volume_, neckLength_] :=
  (c/(2*Pi))*Sqrt[area/(volume*neckLength)];
centsError[measured_, target_] := 1200*Log[2, measured/target];

baseArea = voicingAreaCm2[windowWcm, windowHcm];
baseNeck = wallCm + endCorrectionCm[baseArea];
baseFreq = helmholtzHz[baseArea, volumeCm3, baseNeck];

holeDiameterMmToAreaCm2[d_] := Pi*(d/20)^2;
targetFreq[midi_] := 440*2^((midi - 69)/12);
areaForFrequency[f_, volume_, neckLength_] :=
  volume*neckLength*(2*Pi*f/c)^2;

(* Candidate cumulative area table for A4 to A5. *)
notes = {
  {"A4", 69}, {"Bb4", 70}, {"B4", 71}, {"C5", 72},
  {"C#5", 73}, {"D5", 74}, {"D#5", 75}, {"E5", 76},
  {"F5", 77}, {"F#5", 78}, {"G5", 79}, {"G#5", 80}, {"A5", 81}
};

areaTable = Table[
  With[{freq = targetFreq[midi]},
    {name, freq, areaForFrequency[freq, volumeCm3, baseNeck]}
  ],
  { {name, midi}, notes}
];

areaTable // TableForm

README.md

Project artifact.

Ocarina — Slip-Cast Ceramic Vessel-Flute Family

> *Engineering documentation for a 3D-printed-master, plaster-mold, cone-6-stoneware slip-cast ocarina family — from Helmholtz physics through the parametric design table to a manufacturable build packet.*


*AI-generated concept render — replace with photo of first OCA-P1 prototype after firing. Manufacturing dimensions come from the parametric design table, not from this image.*

What this is

Engineering documentation for a small family of slip-cast ceramic ocarinas, built around the Helmholtz vessel-resonator model and a 3D-printed-master / plaster-mold / Cone-6-stoneware production pipeline. The repository combines:

1. **A parametric design table** ([`ocarina-design-table.xlsx`](ocarina-design-table.xlsx)) — chamber volume, voicing-window geometry, wall thickness, shrinkage, and a 12-hole fingering chart with formula-driven hole-area / cumulative-area / frequency columns. Master scale factor `1/(1 - measured_shrinkage)` is parameterized; for a 12% shrinkage assumption, the master scales at ~1.136×.

2. **A full build packet** ([`design.md`](design.md), [`bom.csv`](bom.csv), [`sourcing.csv`](sourcing.csv), [`cut-list.csv`](cut-list.csv), [`validation.csv`](validation.csv), [`assembly-manual.md`](assembly-manual.md), [`supplier-rfq.md`](supplier-rfq.md), [`drawing-brief.md`](drawing-brief.md), [`visual-bom-brief.md`](visual-bom-brief.md), [`wolfram-starter.wl`](wolfram-starter.wl)) — the same scaffold used across the [`tonykoop`](https://github.com/tonykoop) musical-instrument catalogue.

3. **A capstone slide deck and printable shop packet** ([`capstone-deck.pptx`](capstone-deck.pptx), [`print-packet.pdf`](print-packet.pdf)) — recruiter-facing artifacts that show the design is documented well enough that someone else could build it.

Sister repos: [`gemshorn`](https://github.com/tonykoop/gemshorn) (where slip-cast horn-flute mold workflow was established and is the closest comparable build packet), [`transverse-flute`](https://github.com/tonykoop/transverse-flute) (slip-cast workflow at larger scale), [`flutes`](https://github.com/tonykoop/flutes) (the NAF / open-pipe family with empirical K2 bore corrections), and [`instrument-maker`](https://github.com/tonykoop/instrument-maker) (the agent skill that generated this packet).

Background — what makes an ocarina different

The ocarina (Italian *little goose*) is a closed-cavity vessel flute. Unlike a transverse flute or a Native American style flute, **pitch is set by chamber volume and total open-hole area, not by tone-hole position along a bore**. The governing model is the Helmholtz resonator:

f = c/(2π) · √( A_open / (V_chamber · L_eff) )

where `A_open` is the cumulative open hole area, `V_chamber` is the closed cavity volume, and `L_eff = wall_thickness + 0.6·√(A_open/π)` is the effective neck length with a flanged-port end correction. The full physics treatment is in [`design.md`](design.md) (Governing Model section) and in [`wolfram-starter.wl`](wolfram-starter.wl).

The practical consequence is that ocarina hole positions are an **ergonomic** problem (where the fingers reach), not an acoustic one (where the standing wave wants the holes). This makes the ocarina an unusually clean parametric-design target — change the chamber volume, the whole register transposes; change the cumulative area, the fingering chart re-tunes — but it puts an unusually heavy burden on **fipple/voicing geometry**, which the Helmholtz model says nothing about and which has to be tuned empirically.

Family targets

The first prototype is the magazine-standard **Alto C 12-hole** (target low note A4 = 440 Hz, target high note F6 ≈ 1397 Hz, chamber volume 130 cm³ per the design table). The same parametric model can drive a Soprano C / Bass C extension once the Alto C voicing geometry is stable — see the prototype ladder in [`design.md`](design.md).

|---|---|---|

Hardware alignment — Bambu printer + ceramic kiln

This repo is one of the **slip-casting targets** for the in-flight Bambu printer + kiln pipeline. The build chain is:

1. Parametric design table sets fired-body dimensions.

2. Master scale factor `1/(1 - measured_shrinkage)` scales the master STL.

3. Bambu print masters in PLA (or sealable resin); sand layer lines and seal.

4. Two-piece plaster mother mold around the sealed master.

5. Slip-cast Cone 6 stoneware → demold leather-hard → cut voicing window and finger holes undersized → bisque → tune → glaze → final fire.

6. Validate against [`validation.csv`](validation.csv); fold corrections back into the design table.

The same pipeline serves the [`udu`](https://github.com/tonykoop/udu), [`gemshorn`](https://github.com/tonykoop/gemshorn), and [`transverse-flute`](https://github.com/tonykoop/transverse-flute) repos.

Repository structure

ocarina/
├── README.md                       ← you are here
├── LICENSE                         ← CC-BY 4.0
│
├── design.md                       ← Helmholtz model, design intent, prototype ladder
├── ocarina-design-table.xlsx       ← parametric spreadsheet (formulas, blue inputs)
│
├── bom.csv                         ← bill of materials
├── sourcing.csv                    ← supplier/search tracker
├── cut-list.csv                    ← rough/finished dimensions, tolerances
├── validation.csv                  ← target/measured tuning + cents-error log
├── supplier-rfq.md                 ← RFQ template for slip / plaster / consumables
│
├── assembly-manual.md              ← shop-floor build sequence
├── drawing-brief.md                ← required views + critical dimensions for CAD
├── visual-bom-brief.md             ← visual-BOM art-direction brief
├── wolfram-starter.wl              ← Helmholtz physics starter notebook
│
├── capstone-deck.{md,pptx}         ← capstone slide deck (12 slides)
├── print-packet.{md,html,pdf}      ← combined print-ready shop packet (18 pp)
├── capstone-manifest.json          ← orientation manifest
│
├── cad/                            ← parametric body OpenSCAD starter
├── cnc/                            ← (deferred — slip-cast does not need CNC unless turning a wooden master)
├── drawings/                       ← SVG drawings: section, fipple detail, hole layout
└── images/                         ← AI-generated concept renders (placeholders)

Status

|---|---|

Tier 3 production files (.step, validated .stl, .dxf for laser, .gcode for CNC) are **out of scope until the first OCA-P1 prototype validates voicing geometry**. See the README's status table and [`design.md`](design.md) "Open Assumptions" for the deferral reasoning.

License

Released under [CC-BY 4.0](LICENSE) — original written content, design files, photographs, and physics work in this repository are mine, free to reuse and adapt with credit.