Hi,
I'm having trouble creating a construction plane at an edge.
I loaded a .dxf file and need a perpendicular plane at the indicated line. 
1. The first reference is the right plane.
2. The second reference is the edge through which the perpendicular plane should go.
However, I cannot set angles smaller than 28° and -28°. 

Settings between 27° and -27° produce an error message.

Grüße