Drawing An Ellipse With String
Drawing an Ellipse: The String Method
Step-by-step instructions for drawing an ellipse with the string method—a complimentary Quick Reference Guide to TiC full-length articles, The Elegant Ellipse and Finding the Right Angle. 
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Drawing An Ellipse With String
Source: https://www.thisiscarpentry.com/2013/09/06/drawing-an-ellipse-the-string-method/
Posted by: scalfsooder69.blogspot.com
7 Responses to "Drawing an Ellipse: The String Method"
What a great set of simple instructions. After watching dozens of videos with exhaustive instructions it is a breath of fresh air to see this laid out this way. I am doing this ellipse on a 4×8 ft steel sheet and welding the rods to it. I am using wire instead of string and then taking my plasma cutter to it. I am excited to see the results. Thank you again.
Simply elegant as all good things should be.
So clear and so practical. Like David, I just watched 30 minutes worth of videos and this is the most straightforward explanation I have seen. My fire pit cover will be more refined thanks to you!
This works great, but it's not clear how to establish point C here. The center peak (point C) should be 1/6 of the overall width. So for a 60″ wide cased opening, the center would be 10″ above the major axis or spring line. For a 48″ wide opening, the center would be 8″ above the spring line and so on. In other words a 6:1 ratio for the rise relative to the overall length.
This method covers drawing an ellipse with known dimensions.
For an opening with a semi-elliptical head, point C is located at the desired rise above the midpoint of the spring line (major axis).
As far as a fixed relationship between height and width, I've seen countless examples in both classically inspired and modern architecture that fall outside the 6:1 ratio.
Sweet! Thanks for this explanation!
Very helpful. I was trying to find the proper ellipse to fair the line from my wingtip nosepiece to the tip, if you can imagine 1/4 of an ellipse. It worked beautifully, once I understood it. My semi-major axis was 8" and my semi-minor axis was 4.5". Thank you.