Just a heads up I've come up with the formula for cutting crown molding on a compound miter saw.
I've eradicated any 'not square' issues by knocking out the plaster in the tri-corners which is the source
of misery. Another source of misery is trying to cope the wood to fit, which is a beautiful art only the most
experienced (and costly) trim carpenter can achieve.
For those that would like to add crown to their houses for a more vintage feel, Owl Lumber has a beautiful
coved crown that shouldn't be more than $2-ish per linear foot in red oak..
It goes like this:
For 90 degree corners with a 45 degree crown molding set your saw bevel left at 30 degrees and the miter angle (left or right) at 35.3 degrees.
Right piece / Left edge = Top edge toward you, Knob swung to left.
Left piece / Right edge = Top edge away from you, Knob swung to right.
(bevel angle always tilts left, crown always lays flat facing up)