Hi Jon, the arc from center point command does have an "Elliptical" checkbox option that you can enable to help with that:



When that option is enabled, you will draw an ellipse segment between the start and end point rather than it just taking the angle between those 2 points.


If you have a full ellipse that you want to cut up into sections, you can use the Edit > Trim tool to do that - that's the tool for cutting curves up into pieces.

You can either draw in some lines to use for the cutting objects, or you can click the "Add trim points" button inside of the Trim command to pick some points on the curve for where you want to cut it.

See the help file here for more info on Trim:
http://moi3d.com/2.0/docs/moi_command_reference4.htm#trim

- Michael