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).

001

Again, I extend the segments at right angles to the diagonal line and transfer the line measurements from the semi-circle.

002

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.

003

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.

004

Hope this helps.

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6 Comments on “A little more about creating an elliptical plan”

  1. Sylvain Says:

    It is interesting to see that an ellipse is a circle stretched in one direction.


  2. Now I see and understand it. The smaller A/B circle is just to draw the ellipsis and I can see where having more cheater lines would help to fair the ellipsis at the top and bottom.

  3. wrduffield Says:

    A minor point, but one that might be important to someone in the future searching the web for this technique. The geometric figure you are drawing is an ellipse, not an ellipsis.

    An ellipsis is a punctuation mark that looks like three periods in a row. In MacOS (and iOS devices with a real keyboard connected), you type it with the double key stroke, option-semicolon. In HTML you represent it with the character string … In Windows, you press and hold the alt key while you type 0133.

    • D.B. Laney Says:

      Thanks for keeping me straight. Believe me, an aging brain needs all the help it can get. Corrections are in the works.

  4. Paleotool Says:

    Reblogged this on Paleotool's Weblog and commented:
    Following up on the ellipse.


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