“I believe don’t start if you’re gonna quit”~Eric Church
I became inspired after building the Mini-14 Street Organ to learn about making wooden whistles for musical gizmos. I figured a good place to start was to build an old fashioned wooden train whistle toy. Ya know, the kind of thing kids buy at a gift shop to drive everyone around them crazy for days. A quick internet search revealed plans for the project on The Woodcrafter Page.
The Woodcrafter whistle required drilling four 7/16″ holes into a block of wood: at lengths 4 1/4″, 4 3/4″, 6 1/4″ and 7 1/4″ and and plugging up the whistle end with 1/2″ length of dowel. Well, I don’t own a 7/16″ drill bit that’s 7 1/4″ long – and I don’t feel like buying one. I also didn’t feel like rigging something up to drill a straight hole to that length. I turned my attention to figuring out a way to convert that design to something that can be made with a table saw. I started by calculating the spacial volume of each whistle.
|7/16" Hole Length||My Volume Calculation||Correct Volume|
|3.75"||.52 inch^3||.56 inch^3|
|4.25"||.59 inch^3||.64 inch^3|
|5.75"||.82 inch^3||.86 inch^3|
|6.75"||.97 inch^3||1.01 inch^3|
The length of the hole in the table above has subtracted 1/2″ from each depth because of the inserted whistle dowel plug. For starters, my calculations are incorrect because I subtracted 3/4″ from the length, plus I made a few extra errors. For my train whistle I used my volume calculations.
The first whistle design fixed the length of the whistle to 2″ and height to .5″. The width varied based on matching the spacial volume. Fun fact: Confirmed in hindsight, the length sets the pitch of the whistle. In the case of this whistle there are four whistles and each one simultaneously sings out a D6 note, or 1174.66 Hz. You can hear this whistle by playing the sound below.
So the first whistle wasn’t so great. I learned the length of the whistle determines the pitch. The second whistle I built fixed the height and width to .5″ and the length was adjusted to maintain my spacial volume calculations. The lengths are as follows: 2.08″ 2.36″, 3.28″, 3.88″. This whistle sounds more like a train whistle clearly making three frequencies (show in image at top).
Since I was in the zone I also built a third version fixing the height and width to .5″ and the lengths provided from the Woodcrafter Page. This whistle basically sounds two frequencies, but mostly sounds like one low note. Listen to whistles #2 and #3 here:
What did I learn? This lesson taught me I have a lot to learn about whistles. The Woodcrafter design suggests there should be four frequencies produced, in pairs of two close frequencies. I know why the first whistle only sounds one note – because all for whistles are the same depth. The second whistle may actually produce four frequencies, the two lower frequencies close to each other. I’m uncertain why the fourth one appears to only sound two frequencies. At least two of the whistles constitute the strong lower frequency because it’s wide and strong.
I have more ideas to explore when I revisit the project. And I think I’m going to consult with Charlie, my engineering and math magician friend, before diving in.