Extrude Cut Creates Uneven Geometry/Not Working

Hi Folks,

  First, thank you for your time and your advice! I've been using Solidworks for several years now, but this error has me stumped.

What the goal is:

1. Extrude a curve of an airfoil to make a wing

2. Cut-extrude through the tips of the wing at an angle to allow wingtips to be mated at an angle to create a tip dihedral in an assembly later (please see image).

I'll attach a link to a video of me trying this process and the errors I get. I've also tried creating a solid body extruded through the wing (with the "merge" option deselected) in such a way that when I use Insert -> Feature -> Combine -> Subtract I'll get the angle at the ends of the wings, but the wing tips become strange polyhedrons with a thin skin wrapped around them. I can upload a video of that too, but I'd rather do this with a good old cut-extrude method like I'm used to.

  Thank you again!

       James

10dihedral.jpg.

2016-10-13_20-36-08.mp4 - Google Drive

SolidworksParts And Features