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Perimeter of Ellipse
Patrick O'Hern Jan 23, 2009 12:05 PM (in response to Michael Bourne)Here are a couple of webpages that give calculations on finding the perimeter of an ellipse. Perhaps you can incorporate one of them into a solidworks equation to get what you are looking for...
http://www.mathsisfun.com/geom...llipseperimeter.html
http://home.att.net/~numericana/answer/ellipse.htm 
Perimeter of Ellipse
Roland Schwarz Jan 23, 2009 4:55 PM (in response to Michael Bourne)Modern mathematics has not yet derived a single, finite length, exact formula for the perimeter of an ellipse. The existing formulae are only approximations. Find what works well enough and good luck.
Perimeter of Ellipse
Charles Culp Jan 23, 2009 6:28 PM (in response to Roland Schwarz)Michael,
Consider creating a shape that is not really an ellipse. I have attached a sketch that is 4 arcs, but are all tangent. Note that it looks very much like an ellipse, but is much easier for CNC machines to handle, as it is really 4 arcs. It is also simple to calculate the perimeter.
NotQuiteEllipse.zip 41.9 KB

Perimeter of Ellipse
Patrick O'Hern Jan 23, 2009 6:45 PM (in response to Charles Culp)Try this file out. It's not perfect, but it gets pretty close.
The first sketch has a circle to drive your original seal diameter, then you specify the length of one axis on the ellipse. The second axis is driven by an equation.
The second feature (the circle) is just there to compare the perimeter values.
Ellipse.zip 42.0 KB

Perimeter of Ellipse
Michael Bourne Feb 5, 2009 6:25 AM (in response to Patrick O'Hern)Patrick that was just what I was looking for.
Many thanks


