Carpentry and Woodworking - Crown Molding issue -- wall angle of 225 degrees

All-

I've got a problem -- I am putting crown molding into a room that along one wall has a wall shaped like this:

.......2
XXXX_____
____/
.....1
(.'s are just to get spacing of wall correct)

My issue is with cutting the outside and inside miter for this section in the middle. I've measured them with an angle finder, and found that one is ~ 225 degrees (1, outside) and the inside miter is 135 (2, inside).

I've looked up the formulas and some spreadsheets on how to calculate the miter angle and bevel angle, but they give results that don't make sense.

Here are the formulas I've got:

B = bevel angle

M = miter angle

C = crown spring angle

W = wall angle (what the protractor says divided by 2)



M = tan-1 [tan(W)*sin(C)]

B = tan-1 [sin(M)/tan(w)]

Using C = 45 degrees and W = 225/2 = 117.5

I get M = -60 degrees...... Is that true? My miter saw only goes to 45 degrees... What am I doing wrong? :wall:

Scott

See if this miter calculator works

http://www.scarletta.net/WoodJoy/compound_miter.html

Scott, did it work out for ya?

Thanks for the responses.

Well, after much pondering and visualizing on my part, I realized that I had made two mistaken assumptions:

1) That my molding was 45 degrees :alarm:
2) That I was installing a 52/38 UPSIDE down, therefore making a 38/52 molding :alarm:

Once I figured that out the miter cuts became a little easier. The project is now finished and I have renewed confidence to move onto another room for crown work.

Glad to hear it Scott. Keep that miter calculator handy.

I've had to cut crown on such a tight inside corner where I had to make a jig to hold the crown outward from the fence and cut the degree angle, because 45 degs wasn't tight enough. "What a pain" and very dangerous.