A little more about creating an elliptical plan
Several folks wrote and said that they were having some difficulty getting their heads around this method. Well don’t despair. When I first read about this method, it took me a couple of days for it to sink in. And, if you don’t have much experience with projective drawing, it’ll take a bit of cogitation. Of course, at my age, everything takes a long time to sink in. But it doesn’t necessarily stay “sunk in” for long.
But here’s a little more graphic information that might help. First off, I elongated the major axis to make the model a little more easily understood. So remember, A-B is the Minor axis, A-C is the Major axis. I’ve divided the A-B line into equal segments (with a couple of little “cheater” segments at the ends).
Again, I extend the segments at right angles to the diagonal line and transfer the line measurements from the semi-circle.
I join the dots to create the elliptical line. If I add this elliptical line to the diagonal line running from A to C, I’ve got a 1/2 plan. I could use a flexible drawing spline to “fair” the line. Or if I was working with a wooden plan, I’d simply fair the edge with a fine rasp.
If I want to see a full plan of the ellipse, I simply extend the angled lines and transfer the measurement to the other side. Again I connect the dots and I see the ellipse in full view. This is very helpful if I working in scale on a table, as I can quickly determine the appropriate rectangular measurements for the base.
Hope this helps.
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