Why 31.6 degrees for crown molding?
31.6° is the miter setting for 52/38 crown in a 90° corner, cut flat.
What is 33.9 on a miter saw?
33.9° is the matching bevel setting for 52/38 crown in a 90° corner.
What do 52/38 and 45/45 mean?
The two angles the crown makes with the wall and the ceiling. The chart has columns for each.
Do outside corners need different settings?
No. Same two numbers; only the direction of each cut changes. Your saw’s crown guide shows which way.
What if the corner isn’t 90°?
Measure it with an angle finder and use its row. For 52/38 crown, a 95° corner takes a 29.4° miter and 32.2° bevel; an 85° corner takes 33.9° and 35.5°; a 135° corner takes 14.3° and 17.6°.