A 2013 acoustic study of stave-built didgeridoos across 25 musical keys, plus the engineering documentation, CAD work, and design brainstorming that has accumulated around it since.
Didgeridoo blanks and rough-bored bodies on the shop bench — the physical side of the stave-built wind-instrument problem before the acoustic-length math turns into a finished bore.
Engineering documentation for the stave-built didgeridoo — a long Australian Aboriginal wind instrument that is traditionally made from a single eucalyptus branch hollowed by termites, but that I have been studying as a precision stave-construction problem since 2013.
The repository combines three threads:
- A 2013 acoustic study I conducted in my engineering notebook covering 25 musical keys (C1–C3, with build lengths from ~27" at C3 up to ~107" at C1), with frequency, wavelength, build length, and stave-width calculations for each key.
- CAD geometry for stave-built didgeridoo bodies derived from that table.
- Brainstorming and design work on internal-surface treatments — smooth, ribbed, concentric-ringed — that shape the instrument's harmonic content.
Sister project to djembe, dundun, and ashiko-drum-workshop.
The didgeridoo (also yiḏaki, mago, and many regional names) is a wind instrument with origins in the cultures of the Aboriginal peoples of northern Australia, with continuous documented use for at least 1,500 years and likely much longer. Traditional didgeridoos are made by finding a eucalyptus or bamboo branch hollowed naturally by termites, then trimming and shaping it for sound — a process that yields a unique instrument every time but offers no precise control over pitch or tone.
A stave-built didgeridoo is a Western maker's adaptation: rather than relying on termite excavation, the bore is built up from precisely-cut wooden staves glued in a parallel bundle. This trades the natural variability of the traditional instrument for the ability to target a specific key, length, and bore profile by design. It also makes locally-sourced North American hardwoods viable — oak, maple, cherry, padauk, and so on — instead of depending on Australian eucalyptus.
A didgeridoo's fundamental frequency is set by the acoustic length of the bore and modified by mouthpiece, bell, and bore taper. The basic relationship for a closed-pipe (lip-blown) instrument is:
f ≈ c / (4 × L)
where f is fundamental frequency, c is speed of sound at the playing temperature (~37 °C for warm exhaled breath = ~351.8 m/s), and L is the effective acoustic length.
In my 2013 notebook study I calculated build dimensions for 25 keys from C1 (32.7 Hz, ~107" long) to C3 (130.8 Hz, ~27" long), with stave widths and inner diameters tabulated across three length-to-diameter aspect ratios: 22:1, 24:1, and 26:1. The L:D ratio governs the slenderness of the instrument — at a given length, a narrower bore (higher L:D) produces a darker tone with stronger upper harmonics; a fatter bore yields a brighter, more open sound.
The engineering interest of stave construction is precision: cutting 6, 8, or 12 staves with the right width, taper, and bevel angle to assemble into a target bore is much more controllable than excavating a branch. The stave geometry depends on the target bore diameter and stave count — calculable from the 2013 table.
The primary source for this repository is a 2013 lab-notebook entry (witnessed/signed/dated), pictured below:
The notebook spread: Figure 8-a Key Length & Diameter Table (25 chromatic keys C1–C3), Didgeridoo Diameters bar chart, Figure 8-b Key Dimensions Table, plus brainstorming on stave count, wood species, production paths, and design characteristics. Witnessed and dated.
Contents of that entry:
- Figure 8-a — Key Length & Diameter Table. 25 rows, one per chromatic key from C1 to C3, with fundamental frequency, wavelength at 37 °C, build length, ID at 26:1 / 24:1 / 22:1 aspect ratios, build ID, and actual aspect ratio.
- Didgeridoo Diameters bar chart — visual comparison of inner diameters across all 25 keys.
- Figure 8-b — Key Dimensions Table. Nominal total length, nominal diameter, outer/inner radius, drone length, stave widths (inner and outer), bevel widths, and minimum/maximum widths per key.
- Brainstorming notes on stave count (n = 1 through 8+), wood types (oak, mahogany, cherry, jatoba, maple, lacewood, padauk, etc.), production paths (CNC, community woodshop, Morgan's woodshop, membership shop), and design characteristics (interior surface variants, exterior finishes, bore aspect ratios).
- Research questions noted for follow-up: file types accepted by CNC shops, costs of various hardwoods, lathe sourcing, internal-rib practice cuts, mouthpiece ergonomics and acoustic effects.
The notebook page is the closest thing this repository has to a primary source. The entire CAD and jig design effort is downstream of that table.
(Forthcoming — actively in progress.)
Repository structure is laid out for:
/CAD/bore-profile/— the target inner-bore geometry for one or more keys, parametric in length and aspect ratio./CAD/stave/— stave geometry derived from the bore profile, varying with stave countnand target key./CAD/jigs/— the cutting fixtures. Likely one for the bevel angle (similar to the ashiko sled) and one for the optional internal-rib feature (a router fixture or lathe template).
(Forthcoming — pulling whatever physical builds and prototype photos exist into
/images/.)
In the shop with a peeled didgeridoo log — early stage of a stave-built (or hybrid) build before the bore is established.
- The acoustic question — calibrating the table against measured pitch from physical builds. Does a stave-built didgeridoo built to the calculated dimensions actually play in tune?
- The fabrication question — which combination of stave count, wood selection, and aspect ratio produces the easiest-to-build, best-sounding instrument?
- The portfolio frame — for engineers and recruiters: this repository documents an analytical engineering practice (parametric design tables, bore acoustics, stave fabrication math) that I have been refining since 2013, in parallel with my professional engineering career.
Released under CC-BY 4.0 — use freely with attribution. The didgeridoo as an instrument originates with Aboriginal Australian cultures and has continuous traditional use; the stave-construction methodology, acoustic calculations, CAD work, and analysis in this repository are my own work, free to reuse and adapt with credit.
didgeridoo/
├── README.md ← you are here
├── LICENSE ← CC-BY 4.0
├── .gitignore
├── research/ ← 2013 notebook entry + acoustic refs
├── analysis/ ← parametric calculations, FFT plots (forthcoming)
├── CAD/
│ ├── bore-profile/ ← target inner geometry, by key
│ ├── stave/ ← stave geometry by key and stave count
│ └── jigs/ ← bevel sled + optional internal-rib jig
├── drawings/ ← PDF exports
├── images/ ← finished-build photos + figures
└── reference/ ← any reference documents
| Section | Status |
|---|---|
| Repo description, license, gitignore | ✓ done |
| 2013 notebook entry (primary source) | ✓ photographed and committed |
| Hero photo | forthcoming |
| CAD — bore profile geometry | not started |
| CAD — stave geometry | not started |
| CAD — jig designs | not started |
| Physical builds | searching personal archives |
Living document — the primary-source acoustics table is already in place; CAD geometry and recovered physical-build documentation are the main remaining additions.