In the attached file, the red was created using planar surfaces at the top, bottom and sides, a loft towards the end and a networksrf at the right. They were all joined together and shelled.
The purple surface is a loft and planar surfaces at the top and bottom. The surface at the top of the purple and the bottom of the red were created from the same curves (prior to shelling).
Yet boolean union fails on these. I can use extractsrf at the matching points join, and cap to union but I was wondering why this causes Boolean Union so much trouble?Problem Union.3dm (4.3 MB)