A penny whistle (or Irish whistle, etc.) uses a vibrating stream of air that resonates inside of a tube of a given length to produce sound waves at a given pitch. In this Instructable, we'll show you how to design and build your own penny whistle using a 3D printed mouthpiece and a PVC tubing body.

This instrument was designed as part of the WAVES program, which is exploring the common ground between the STEM disciplines and the Arts

Explore the model in Fusion360.

Step 1: Background: the Fipple

The distinguishing feature of a penny whistles as compared to other types of flutes is that it uses what is called a fipple to produce the vibrations. A fipple is a type of mouthpiece where a stream of air is blown through a channel and cut by a blade, which allows a thin sheet of air to pass beneath the blade. The fipple makes it easy for the player to set up the vibrations, but gives the player less control over shaping the note, as compared to say, a flute. The animation above air vibrations from a fipple is from Air Vibrations in a Recorder (in Dutch).

Step 2: Designing the Mouthpiece With Sketchup

The PDF file below has step-by-step instructions for designing your own mouthpiece using the free 3D drawing tool Sketchup. The video shows the details on the most critical step in the design, getting the spacing between the fipple blade and the airway right!

Sketchup Whistle Instructions.pdf
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Step 3: 3D Printing Tips

Depending on your 3D printer, you may have to play around with mouthpiece before you can get it to make a sound. Note that you won't hear anything unless you attach the mouthpiece to a tube (which you need to produce the resonant standing waves that you hear)! A tube length of around 6" should be a good start. If you don't hear anything, the first thing to check is the space under the fipple blade. Make sure that it is not obstructed. If there is any wax or other support material, clean it out. On some printers, we've also sometimes seen a small blob of plastic on the underside of the blade, which we needed to sand off using an emory board.

Step 4: Preparing the Tube

The pitch or frequency of the note produced by a whistle depends on the tube length, where the shorter the tube, the higher the frequency, or more specifically, the frequency is proportional to 1/(tube length). By cutting holes into the whistle tube, you effectively shorten the tube, raising the pitch. By carefully placing the holes and covering them with your fingers, you can create an instrument that can play the notes of a scale. A traditional Irish Penny Whistle has 6 holes tuned to play a D major scale; fingerings for these notes are illustrated above.

Start with a tube cut to 240 mm (9 7/16 inches). Note that you must use 1/2" schedule 40 PVC tubing or you will be out of tune.
Attach the mouthpiece and using a tuner (such as Track Tuner for an iPhone) verify that it plays a D. If the note is flat, sand off a bit of the end of the tube and if it is sharp pull the mouthpiece out a little (if it is very sharp you'll need a longer tube).
Print out a copy of the hole placement drilling guide PDF file above. Remove the mouthpiece and wrap the drilling guide around the tube. Drill small pilot holes (no more than 1/8") at each of the markings.
Reattach the mouthpiece, cover all the holes and blow. You should still get a D.
Cover all but the bottom hole with your fingers and blow. You should get a note somewhat flatter than an E as indicated by a tuner. Using the point of a pair of scissors, widen the hole slightly and play. The tuner (and your ears) should indicate the note getting sharper, closer to an E. Keep working the hole with the scissors point until the E is in tune.
Cover all but the bottom two holes with your fingers and repeat the process with the second hole from the bottom until you get an F# in tune.
Repeat the process for the remaining holes, using the fingering chart as shown above.