How do I draw a superellipse?

Experimenter
Experimenter

I need to make a superellipse so I can replicate a pen cap for an idea I am working on. I know there is a way to make an ellipse but the problem is that the dimensions I am putting in aren't really working.

 

I am using Solid Edge Design1, which is a monthly subscription license through Local Motors. 

 

Attached is a picture of the profile I am trying to make. 

5 REPLIES

Re: How do I draw a superellipse?

Esteemed Contributor
Esteemed Contributor

Hi there,

 

I placed geometry over your image to rough it out quickly.....perhaps you could try something like the attached?

[add dimensions & relationships for greater control, if needed]

Sean Cresswell
Design Manager Streetscape Limited
Solid Edge ST10 [MP2] Classic [x2 seats]
Windows 10

Re: How do I draw a superellipse?

MLombard
Retired
I don't know of a CAD program that can create a superellipse directly. Possibly as part of an equation driven curve. Or you could approximate one as Sean mentioned, or using 4 conics (one conic mirrored twice). or even more approximate one spline with tangency controls mirrored to create 8 total sections (mirrored 3 times) around the loop.
Retired Community Manager for Solid Edge. This account is no longer active.

Re: How do I draw a superellipse?

Community Manager Community Manager
Community Manager

So Matt is right -- a true superellipse probably requires an equation. But here is a very handy construct that I use often that might get you very close. Basically you:

 

1. Draw a three point spline.

2. Align the endpoints with the origin.

3. Align the first arm of the spline horizontallly and align the opposite end vertically.

4. Use the mirror command and mirror it about Horizontal axis.

5. Use mirror again to mirror about vertical axis, and again about horizontal to get closure.

 

Voila -- a super well behaved spline that can create any variety of shapes, including something quite close to your superellipse.

 

PS> You could also constrain the arms to be equal length if you were after that degree of symmetry.

 

See here: http://www.youtube.com/watch?v=BmNrF1ZuLYo&feature=youtube_gdata

 

 

Dan Staples
Director, Solid Edge Product Development

Re: How do I draw a superellipse?

Siemens Phenom Siemens Phenom
Siemens Phenom

Well that made for a good evening’s distraction! Thank you for the challenge. I now know more about superellipses than when I woke up this morning Smiley Very Happy

 

Attached is a Solid Edge part file with a Curve by Table generated from an embedded Excel spreadsheet that will allow you to tweak and change your superellipse parameters.

 

screenshot.6.png

 

I think the spreadsheet is self-explanatory but have added a few brief notes for pointers. I also included a chart in the spreadsheet so you can preview the curve before committing to Solid Edge.

 

screenshot.3.png

 

screenshot.4.png

 

For those that want just the standalone Excel spreadsheet to generate the superellipse for other applications, the Excel file can be snagged from GitHub.

Re: How do I draw a superellipse?

MLombard
Retired
Very nice! Thanks for that!
Retired Community Manager for Solid Edge. This account is no longer active.