Ellipse problem

[franck.gressier]

It seems that trimming off a part of an ellipse is "complicated".

In the file joined, I just cannot split it (break function or trim).

I was able in another sketch to do that but then, If I want to make a loft using 1/4 of ellipse and the line as rail, it says it is not G1... But I cannot specify a tangent constraint (overconstrainted...).

If I use a circle instead, the tangent constraint appears by itself and I can break or trim it as I want...

[jeff_strater]

you can trim an ellipse.  Sometimes, Trim is confused by trim curves that don't have a "clean" intersection with the target.  In this case, if you over-draw the trim curves, you can trim the ellipse.  And, afterward, you can make that line tangent.

However, it is worth pointing out that ellipses, and even more so trimmed ellipses, are not supported as well in Fusion as other curves, unfortunately.  I've seen cases where the ellipse can "flip" due to some constraint, etc.  So, be aware of this as you try to use them.

Second, you say that you want to use the quarter ellipse as a profile for a loft, and the line as a rail.  Can you be more specific about what you are trying to do with loft here?  You cannot have profiles and rails that are all co-planar in loft.

screencast:  https://knowledge.autodesk.com/community/screencast/f3bda236-fec8-44c3-9108-81399d667a18 

[franck.gressier]

Thanks for the reply.

I have found time to look at it again and the trimming and splitting seems to work now . (???)

However, for the loft problem , I had to waste 3h on it not to understand what was happening...

I came up with another ellipse issue. When you specify a tangency to an ellipse the axes go wild ...

In my initial drawing the ellipse was very slightly sideways (I don't know why ...) And so I made a new file exaggerating that. When I specify the tangency, the minor axis of the ellipse goes vertical and doesn't match the center of the ellipse annylonger...