HOW DO YOU CUT A INSIDE CORNER ON CROWN MOLDING USING A POWER MITER SAW ?

If you know that the intersection is a true 90 degrees, then Dragonfire's answer is right, however, if the intersection is something else, you will need two wood blanks (1"x2"x8" is a good size).

Hold the first wood blank to the left wall & push it to the corner you want to determine. Hold the second wood blank under the first, against the adjoining wall & have someone scribe a line to the bottom of the first piece, along the edge of the second piece. You now have a cut pattern for the left piece of crown molding...simply set your saw to the pattern.

For the cut pattern for the right piece, erase or scratch out the previous line & use the same procedure, however, place the right block first & the left block under it, marking the right block.

You can determine whether the walls are at right angles to each other by placing a speedy square in the corners you want to check.

Good luck...

If you have a compound miter saw, set two 45s. If not, place the molding against the fence at a 45, set the saw to cut a 45 with the longest part being toward you. The main thing to remember is that the bottom of the molding is going to be longer than the top for ALL inside corners. You will have to change the saw to the opposite 45 for the adjoining piece. For example, if the corner is going to be to your right as you face it, cut the piece to the left of the corner longer on the right, and vice versa. I sometimes use a couple of short pieces to start, just to be sure when I haven't done it for awhile..

if you want to lay the crown flat on the saw then the miter and bevel angles should be at 32.4 degrees to start. you'll have to adjust a little to get it perfect. i've never had much luck this way because it's hard to determine which angle needs to be corrected. dragonflies method is easier. if you clamp a straight edge to the bed of the saw the angle that you hold the crown to the fence is constant and you'll only have to adjust the miter to get it perfect.

most crown molding guys cut and cope

that is one run is cut straight corner to corner

the other is then cut at 45 degrees and then coped saw to fit tight

beats inside mitering every single time as you are assured tight joints

otherwise make a jig to hold the crown ( cut upside down BTW ) at 45 degrees to the fence, the compound cut is set to zero, the mite set to 45 degrees, few pros cut the crown flat with a compound saw

Measure the angle with an adjustable protractor and divide by 2 to get the angle for the cuts.Measure the angle because most houses are surprisingly out of square-don't assume that a corner is 90 degrees.

great tips and video here

http://www.ehow.com/video_4417863_cut-crown-moldin...

Good luck !