3D Printing the 2600 Whistle


Perhaps the most legendary piece of plastic in the hacker community is the humble "Cap'n Crunch" whistle. The free-in-cereal whistle was able to emit a piercing shriek at 2600Hz - the exact tone required to unlock the US phone network.

So, because it's all I seem to do these days, I turned my my trusty RepRapPro and decided to see whether it was possible to 3D print a whistle which could produce the same frequency.

I found a customisable whistle on Thingiverse and customised it to include the Over The Air hashtag.

Rather than do any funky customisations with radius or length, I simply scaled the whistle in Slic3r.

3D Printed Whistles

I made them at 75%, 85%, 100%, and 100%.

The print wasn't without issues. Because of the large opening, the top layer didn't seal properly - even on the smallest print.
Whistle Holes
The logo printed reasonably well - and the holes in the side were easily sealed with my fingers. But I might adjust the model for a thicker top layer.

The models come with an integrated "pea". The little ball in printed inside the barrel - a hard poke with a sharp stick set the ball free.

So, how did it sound?

Not bad! We broke out a tonal analyser on a smartphone and, on the smallest whistle, I managed to just about hit 2600Hz!
All 4 3D Printed Whistles

The 3D print is rather rough and was quite harsh on the lips - so it's worth sanding the final print down or rubbing some acetone on it before blowing.

Now, obviously, this doesn't look exactly like the original whistle. There are no 3D models I could find - although there are several rather detailed photos.
Cap'n Crunch Bosun Whistle

For my next step I can go one of two ways. Either refine the existing whistle so it reliably produces the 2600Hz tone - or try to make a replica of the bo'sun whistle and then get that pitch perfect. Thoughts?

Oh, and the tone is really loud and annoying for anyone nearby!

2 thoughts on “3D Printing the 2600 Whistle

  1. You need the original to make a mold of. If you ever used the actual whistle you would know you needed to cover the holes to produce 2400hz as well as some trunk required both tones.

What do you reckon?

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