Transition From Rectangle to Circle In SketchUp

Way back when I was in design school (board drafting with T-square and pencil) one of my teachers mentioned that people who work with sheet metal duct work know more about practical geometry than anyone in the world. I was reminded of that earlier today during an online SketchUp class session.

I was working with a few students who had taken my last live class, and toward the end of the session one of them posed the problem of making an object in SketchUp like the one in the image at right. It transitions from a 24″-diameter circle at the top to an 18″ x 36″ rectangle at the bottom. With the top circle larger than the rectangle below, lines on the perimeter of the circle crossed the lines of the rectangle and that made things a bit messy. As the class was winding down, I couldn’t come up with a simple, elegant solution.

You know you have a good student when he sends an email 45 minutes after the end of class describing his attempts. He did pretty well as long as the circle fit within the rectangle. It occurred to me that use of the scale tool on the circle, after the basic shape was established made sense. So off to the computer I went. It’s a little tricky as four triangular planes connect with four triangular curved surfaces.

The video below walks through the steps to create this wacky shape:

If you want to learn SketchUp, the easiest way is to work with someone who knows how to use the program, and how to solve problems like this one. If you try to teach yourself via random YouTube videos it will take a long time and you just might pick up someone else’s bad habits or inefficient techniques. Click Here for information on SketchUp classes in general.  I’m planning on more classes this year, both live and online. You can help plan my next class if you:

Click my signature below to send me an email if you’re interesting in having me teach a class tailored to your group or organization, or if you are interested in online SketchUp tutoring.

— Bob Lang