Mujitsu and Tairaku's Shakuhachi BBQ

we want to 3d print of a shakuhachi with precision measured and copied from ancient very important shakuhachi bore but we want to print the body with internal structures natural or better for bamboo sound vibration . What are the options ? fdm is best

✅ 1. What matters most for shakuhachi sound

A shakuhachi is extremely sensitive to:

Bore diameter changes down to 0.1 mm

Internal wall stiffness and damping

Mass distribution along the tube

Surface texture inside the bore

Node/anti-node behavior influenced by micro-resonant structure of bamboo

A bamboo shakuhachi is not just a smooth tube ? the inner wall has:

natural fibers

tiny ridges

longitudinal grain

varying density
→ These subtly shape the formants and brightness.

A perfect plastic tube with the right shape will play, but won?t sound ?bamboo?.

So the job is:

✔ Copy ancient bore measurements perfectly
✔ Add internal microstructures that mimic bamboo?s acoustic impedance

2. Why FDM is actually excellent for shakuhachi

FDM naturally creates:

layer lines (longitudinal or spiral)

variable wall thickness

anisotropic stiffness

These properties accidentally resemble bamboo.
But they must be controlled, not random.

FDM gives you:

Stiff outer shell

?Fibrous? internal walls

Option for custom infill patterns that behave like bamboo nodes

This makes FDM better than resin for musical instruments.

✅ 3. Local wall structures that mimic bamboo (very important)
A) Natural bamboo ?fiber? imitation (best choice)

Printed along the tube length:

Print upright, single perimeter, spiral vase mode + 100% flow
→ Produces:

continuous helix grain

micro-ridges that behave like bamboo fibers

light but stiff tube

This gives the closest acoustic behavior to bamboo.

B) Artificial bamboo nodes

Add internal ?node rings? every 18?22 cm (depending on the original bamboo), with:

1?2 mm thick rings

1?3 mm high

They introduce:

damping at certain frequencies

harmonic warmth

slight impedance steps (real bamboo has this)

You can tune timbre by making nodes softer or harder.

C) Micro-texture inside bore

Ancient shakuhachi are not mirror smooth.

What you want:

Surface roughness Ra = 0.05?0.15 mm
The best method:

Print the bore with intentional 0.12?0.18 mm layer height
The groove pattern imitates bamboo inner texture and moves air column energy in a way closer to bamboo than resin.

✅ 4. Internal honeycomb for natural vibration

If you print walls 3?6 mm thick, the internal infill pattern matters a lot.

Best infill patterns for shakuhachi:
Infill    Benefits
Gyroid (10?15%)    Most bamboo-like resonance, curved structure spreads modes
Cubic Subdivision    Very stable tone color, slightly brighter
Lines (aligned with tube)    Very warm, ?fiber-like?, extremely bamboo-like

Gyroid inside + spiral vase outside is incredibly effective.

✅ 5. Material choices
Best FDM materials for shakuhachi
✔ PLA+ (best for pure sound & stability)

Very stiff

Very predictable

Best pitch stability

Tone: warm, stable, close to lacquered bamboo.

✔ PETG (brighter, more bamboo-like damping)

Slight flex = natural bamboo damping

Very smooth bore possible

Tone: brighter, more lively.

✔ Polycarbonate or Nylon (professional level)

Strong but too flexible unless wall is thick

Great overtones

Tone: resonant, but may be too ?alive?.

❌ Not recommended

Resin printers → too dense, too smooth, too glassy (sounds like a recorder, not shakuhachi)

Flexible filaments → kill harmonics

Metal printing → too heavy; modes move into unwanted ranges

✅ 6. Hybrid method (best of all)

Use FDM to print the bamboo-like structure, then coat the bore with Japanese urushi-style lacquer alternative.

Steps:

FDM print, textured inside

Apply very thin layers of:

polyurethane varnish, or

casein glue, or

acrylic lacquer

Purpose:
✔ smooth micro-ridges (but not fully)
✔ give reflective surface like real shakuhachi
✔ seal moisture

This improves pitch stability dramatically.

✅ 7. Bore measurement copying

If you have the ancient shakuhachi:

Methods:

CT scan (best; 0.05?0.1 mm resolution)

Photogrammetry + internal stitching

3-point bore gauge every 1 mm

Digital caliper on a long rod

For professional work:
Export a radius vs length CSV, fit it to a spline, and revolve in CAD.

⭐ Final Recommended Build (most bamboo-like)
Print settings

FDM, PLA+

Orientation: printed upright

Layer height: 0.12?0.18 mm

Wall: 1 perimeter (spiral mode) + varnish

Infill: gyroid 12%

Bore: exact spline from ancient shakuhachi

Internal bamboo simulation

2?3 bamboo node rings

Light inner micro texture

Variable wall thickness (slightly thicker near utaguchi)

Result

✔ Warm bamboo timbre
✔ Ancient bore accuracy
✔ Stable pitch
✔ Strong harmonic behavior
✔ Extremely playable
If you want, I can:

▸ Generate a complete Fusion 360 model ready for printing
▸ Produce a parametric shakuhachi generator
▸ Offer node tuning for specific tone colors
▸ Produce a bore CSV → DXF → STL pipeline

Just tell me your bore measurements or what key (D, E, F, G, 1.8, 2.0, 2.4 etc.) you want.