Comments on: Elliptical Shapes Using Simple Geometry – video

By: Steve Shanesy

Steve Shanesy — Wed, 06 Jun 2012 13:28:37 +0000

Hi, Larry,

Yes, there seem to be limitations of the false ellipse with regard to the ratio of major to minor axis. While elongated shapes or fatter elliptical shapes may be useful for some applications, I’ve found the sweet spot for pleasing false ellipse shapes has the length of the minor axis somewhere between 55% and 75% of the major axis.

Steve

By: larrydwilliams

larrydwilliams — Wed, 06 Jun 2012 02:16:02 +0000

You will find that as the difference between minor and major axis becomes larger, so does the variation between an oval (what is being produces here) and a true ellipse. Most of the time, the oval generation is good enough for woodworking. However, if I am doing something like a Stickley style bracket, I prefer to use a hyperbolic curve generation so that the curve radius constantly changes.

By: McDara

McDara — Tue, 05 Jun 2012 15:56:11 +0000

Steve,
It has been more years than I would like to admit that I have done the exersize you have shown (7th grade drafting class, I’m now 60). Just for my morbid sense of curiosity I duplicated your instructions using a CAD program. Then I used the Ellipse function to draw over the “false ellipse” in a different color. The difference is increadably minor.
If you draw a line from the center of your right or left arc at a 45 degree angle crossing the false ellipse and an actual ellipse you will see about 1/16″ departure at the 45 degree line.
Yes I know I am a geek.

By: hutchjo

hutchjo — Mon, 04 Jun 2012 02:31:09 +0000

Rats. Busted. The first thing I was going to do after my last reply was throw out my laptop. “IT” decides when to send things before I get a chance to proof-read or finish what I was starting to say. “IT” decided that “wewe” was funny when I was trying to say “were.” Reading it once again, however, makes me wonder if “IT” was right. The thought of making wire legs DID make me want to wewe (or weewee or whatever).
Lastly, before “IT” deciced to send, I wanted to say that the Egypoid legs seem to capture the basic look and proportions of the original Superellipse Table legs without getting into the realm of bent wire. Mockett uses metal plate but I’m wondering if they could be fabricated from Baltic Birch plywood?
And that’s all I have to say about that.
Nice chatting with you again, Steve. I miss it.
John
Disclaimer: I swear that any mistakes in the above text will remain uncorrected.

By: Steve Shanesy

Steve Shanesy — Mon, 04 Jun 2012 01:25:32 +0000

Hey, Keith, now you are making me feel old!:). When I was went to night trade school for cabinetmaking, we learned how to do this geometric work for false ellipse, gothic headers, French headers and more. When I went to work for a custom furniture company in Los Angeles, we used the false ellipse geometry to make some remarkable conference tables, some being up to 40 feet long.
Thanks for your comment, and yes, your math degrees are showing. Heck, one of the main reasons I elected journalism as a major was there was no math requirement.
Steve

By: Steve Shanesy

Steve Shanesy — Mon, 04 Jun 2012 01:16:01 +0000

I thought that was probably you, John. Hello! Long time, etc. Yes we made a very good team on the Tornado Table project. It was truly a collaborative effort that produced excellent results. I still have (and cherish) the two I built.
I’m still uncertain where I’m heading for the dining room (space) table, but the superellipse is very interesting and something I want to look into more. Thanks for introducing the idea. Perhaps another collaboration is in the cards.
Steve

By: hutchjo

hutchjo — Sun, 03 Jun 2012 23:41:35 +0000

Steve,
I don’t want to turn this into a superellipse promotion but I was thinking about building one a few years ago. The only thing (only thing?) that stopped me wewe the wire-rod legs. When I looked for a sourced leg, I hit the wall until I saw the Egypoid Leg on the Doug Mockett website. It’s not wire but rather “intersecting planes of inverted triangles.”

By: hutchjo

hutchjo — Sun, 03 Jun 2012 21:05:35 +0000

“Sure” wish I could type.

By: hutchjo

hutchjo — Sun, 03 Jun 2012 20:54:17 +0000

Steve,
Fritz Hansen, a furniture manufacturer in Denmark, is still making the Superellipse Table in various configurations. Unfortunately, they only seem to be offering them with a white laminate top. We had two in our conference rooms in Columbus with teak tops and pencil edges. They do give you the feeling that there is no “head of the table.”
If you’d like to pursue the notion of a superellipse table any time in the future, I’d be more than happy to be your go-to guy for some full-scale drawings. I thing we made a good team on the Tornado Table and I’m aure we could do it again. Think of the great sidebars!
John Hutchinson

By: keithm

keithm — Sun, 03 Jun 2012 17:08:49 +0000

Yes, technically not an ellipse (the set of all points the sum of whose distance from two points (the foci) is equal) [cf. circle, the set of all points whose distance from a single point (center) is equal (the radius)]

x^2/a + y^2/b = c (an ellipse)

x^2 + y^2 = r (a circle)

What Steve has constructed is often called a draftsman’s oval and is really close, but not exact, to an ellipse. A good article on this (see the diagrams) at http://en.wikipedia.org/wiki/Oval

But I really love compass and straightedge constructions. Many of which quit being used after my grandfather’s generation.

Are my two math degrees showing?