Can't Make Ellipse Roof by Extrusion

[ctc]

Revit returns the error "can't make extrusion" when I attempt to create and elliptical roof shape by extrusion.

My open loop sketch includes the top half of an ellipse and no matter which "rafter cut" I select I receive the same error.

[roy.70844]

There is some relationship that links the size of the major and minor axes. If the minor reaches some minimum point the roof can not be made.
Have a look at the images in the first, the roof works. In the second it fails and is fixed by reducing the length of the ellipse by pulling the sketch-line handles (third image).

I think you need to avoid too tight a curve at the end of the ellipse, it probably causes some kind of self-intersection of the solid.

Roy

[lev.lipkin]

I wonder if the curvature of ellipse at the end does not allow roof thickness to fit.

[nole]

Hi there!
One of my very first posts were about constructing ellipse, but I cannot find it. So, here it again.
Ellipse can be constructed this way (http://forums.augi.com/attachment.php?attachmentid=20966&stc=1) but You cannot use it to make extruded roof (Revit error message - Factory?).
Because of that, You should construct extruded roof in parts, then Join Geometry (see pict. (http://forums.augi.com/attachment.php?attachmentid=20967&stc=1)).