About the Prusa Mouth Organ
A harmonica you can print, reeds and all. The Prusa Mouth Organ has three parts that clip together with no screws: a comb, a cover and a printed reed plate whose thin plastic tongues are the reeds. The supplied plate is tuned to an A-minor scale from A4 up to A5. This version has blow reeds only, so you won't get the draw notes of a normal harmonica.
The reed plate is the clever and fussy part. Each reed has to swing freely inside its slot while leaving as little gap as possible, because a tighter fit means more sound. That makes the result very sensitive to your printer, filament and slicer settings, especially the first layer. The designer prints the plate on its own and recommends a specific PLA and settings, given below.
Reed plates are swappable, and the designer includes STEP files and a blank comb, so you can experiment with your own note layouts or add text to the comb in your slicer. A print-in-place carry case was added later.
Who it's for. Curious makers, and anyone who enjoys tuning a print by trial and error. If you mainly want to play harmonica, treat it as a fun experiment, not a replacement for a metal-reed instrument.
What you'll need
Printed parts
- Reed plate (print it on its own)
- Comb
- Cover
- Optional: print-in-place carry case
- Optional: blank comb for adding your own text
Bought parts
- Nothing
Tools
- A well-tuned printer with a good first layer (the designer used a Prusa MINI+ on a smooth PEI sheet)
Build overview
- Print the reed plate alone. Give it your best first layer; the reeds must not touch the plate.
- Fit the plate to the comb. Slide it under the rear lip of the comb and press it down flat, as airtight as you can.
- Free the clips. Make sure the side clips on the comb spring back; loosen them if they're stiff.
- Clip on the cover. Push the comb assembly into the cover until it clicks, then play.
Print settings
- Material: PLA; the designer used Polymaker PolyTerra for the reed plate
- Layer height: 0.2 mm for all parts
- Reed plate: 1 bottom layer, 2 top layers, 15% gyroid infill
- Other parts: Your usual settings (PrusaSlicer 0.2 mm Quality defaults)
Video
Play video: The Prusa Mouth Organ, a printable harmonica (loads Vimeo)
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Photos
All photos: Y Ibrahim, from the design page on Printables, licensed CC BY. We resized them and converted them to WebP, and used the first frame of animated images.
3 more photos on Printables ↗