eganders wrote:

What about if the ceiling is not a perfect 90 degrees? How do you
compensate for the miter angle. Do you measure the inside angle and
compensate?

I use a long protractor that determines the angle. If it's a 88 degree you
set the miter to 44 degrees. There are tables in good crown molding books
that give you the bevel angle according to the spring angle of the
particular crown your using, usually 38* 45* or 52* You cut it flat on your
miter, no need to do the upside down and think backwards routine, and angle
it on your fence and have a stop to hold it. This is great since most
miters have a hard time with 6" or wider crown against the fence.

It also helps to have a couple of templates of the cuts specially inside
ones that you label inside left, inside right so you can use them to setup
the right side of the crown to cut. When you install as much crown as I do
you don't need to do this.