Tapered Half Moon Groove

Hello and greetings to all…

I make Native American Flutes and are having trouble making a tapered hollow sound chamber inside, so decided to have a go with SketchUp and hopfully finally using a CNC machine… but this is my problem… drawing it:


This is my first post and I don’t see my image, only an upload path (Hopefully it will appear when posted?)

I’m using 50mm wide, 500mm long, 25mm deep strips of wood.

I’d like to make a tapered chamber, say 25mm wide at one end and 20mm wide and the other. The length of the chamber will be approx. 300mm - 500mm. Once I have two identical halves, they are glued together to form the body of the flute. hopefully giving me a 25mm bore at one end and 20mm at the other.

I’ve tried many different methods with no success. Can you help or have I got the wrong package?

John Long

Here are some suggestions with basic tools in SketchUp. With such a small item, you may want to scale it up to work on it, and then scale down for output (or look up the “Dave Method”). I am sorry if the example may look crude and exaggerated. I am not totally sure about your process, but this is regarding making shapes in SketchUp


Thank you pbacot, I kinda know where you are coming from and will certainly give it a try, I thank you again.

John Long

You’re welcome! Good luck! In my distant past I leaned to make Lakota tipis covers from canvas, and stayed in one for a summer. Though I am not a native American, it changed my life.

Instead of making two shapes you can also draw the block shape based on the finished cylinder, when you get to that point, and you may find alignment easier that way. But this way isn’t hard either when you have some practice moving and aligning shapes in SketchUp.