Reverse Engineer a Whistle with Fusion 360

Here's a fun project that combines Fusion 360, 3D printing, and some aerodynamics. It will make for a great weekend project or classroom project.

I started with a real injection molded plastic whistle that I bought from Dick's Sporting Goods. I wanted to recreate the whistle but rather than following someone else's tutorial or looking for schematics on the internals of a whistle, I decided to saw the whistle in half and take a look inside. You know, it's like when you were a kid and took apart stuff just to see how they work. And just like the old times, we won't be able to put this one back together. But that's ok because we're going to recreate it.

The workflow I'm going to follow is a powerful one that I use often in recreating a part. After cutting the whistle in half, I now have access to the internal geometry. I can then take a picture of it and import it into Fusion 360 by going to Insert - Canvas.

Unfortunately, when you bring in an image, Fusion doesn't know what the correct size is, so you'll have to give it that information. This is easily done by using the Calibrate function to resize the image. Simply right click on the image within the browser section and select Calibrate. The Calibrate tool works by simply clicking on two points in the image and entering what the distance is between those two points.

Now that the image has been resized, we can simply create a sketch and trace the internals. This design is simple enough that all we need are a couple circles, a rectangle, a few lines, and an arc.

The next step is where all the magic happens. We use the Extrude tool to turn our 2D sketch into 3D geometry. We apply a few Fillets and voila! We have a 3D model of a whistle to send to our 3D printer. The print is straight forward and does not require any supports or extra post processing.

To make this a real whistle, we'll next add the little cork ball that bounces around in chamber to give it that extra loud trill. An option is to print the ball in place and then use a thin screwdriver to pry it loose. But I wanted to keep the design simple while also trying to reproduce a whistle that is as close to the original as possible. Real whistles actually use a cork ball inside. Because cork is pliable, you can insert a ball that's bigger than the opening. And once you insert it, you can be sure that it will stay in the chamber.

To accomplish this, I simply cut off a small piece from a wine cork and then used 60 grit sandpaper to form it into a ball. This worked like a charm. The completed whistle exceeded my expectations. It looks great and is indistinguishable in loudness and sound from the real thing!

My big aha! moment with Fusion 360 happened when I finally understood how to use Constraints. Get my free Fusion 360 Constraint Cheat Sheet and see what I mean.