Walls and Ceilings - crown molding

i'm having trouble with the outside corners. i figured they'd be 45degree angles to meet at the corner and that seems fine, but at what angle to i cut from top to bottom? does that make any sense?

If you can stand the crown up to cut it, the angle is 45 degrees.

Yeah, crown molding can be tricky. Basically, you want to stand the molding upright as you cut it, with the flat part that will go against the wall being flat against your mitre saw or mitre box. That means, the whol back of the molding will not be against your mitre saw or mitre box--JUST the actual part that will lay flat against the wall. It can be difficult to hold like that (especially if you are cutting by hand), but don't worry if it doesn't match up 100% exact at any corner (it never does). A tiny bit of wood filler and about 20 seconds with some fine sand paper will fill any gap quite easily so that you can't even see where the seam was.

TO get the proper degree, do this.

Take 2 straight flat boards (1x4 or 1x6) and put one on either side of the corner against the ceiling so that they are overlapping. (Kinda like a cross) Now make the line on the bottom board where the top board covers it on both sides.

Take the bottom board down and draw a straight line from one corner to the next (from the wall out). The lines will look like an 'N'. Set up the saw using this angle and then cut, you should have a near perfect angle cut.