Cope Joint at 45 Degrees.

[Richard Gillespie]

I know how to cope a joint when it is an inside corner at approximately 90*. I'm installing crown molding and have to deal with two 45* inside corners. My mind tells me to use the same procedure but the mating piece has to be cut at a angle sharper than 45*. Anybody care to comment?

[Dave Crabbs]

Richard,
I would think that if you cope the crown molding like you would for a 90* inside corner it should work for any angle. The only difference would be that the piece you are butting the cope joint to (the piece with the square cut on the end) would have to be cut at the wall angle. I would try a couple of test cuts on some short pieces of crown molding and see if it works first.

Just my 2 cents
Dave

[Jim Becker]

I'm with Dave, at least from mental visualization. You may need to back-cut it farther to bring things together cleanly, but the profile, I believe, would be the same. The the only reason you do the angle cut, to get the profile visual for coping. But I could be totally whacked out on this!

[Steve Clardy]

Cut one side 45, then the other side about 46 or 47. This will let the back of the cut not interfere with the front of the cut. Do a test cut with scraps first.
Steve

[Richard Gillespie]

Guys, I found that when the angle is at 45 degrees, coping would be very difficult. The best solution ended up being a mitered joint.

[Nathan Hoffman]

Maybe I'm not picturing this correctly, but shouldn't you always bisect the joint angle? Most of the time it is 90, hence the 45 degree cuts, so shouldn't this be just half of the angle between the walls? So you basically miter one side, and that gives yo the profile you need, right? Regardless, Richard, I'm glad you were able to get it work.

[Jason Roehl]

I think Nathan's right here...matching the profile at 90* is very different from matching that same molding profile at 45*. I would think that if the two pieces meet at a 45* angle, you would have to make a 67.5* (most saws, 0* crosscut) miter to reveal the coping profile. To visualize, cope a piece like you would for a 90* joint. Hold it up to its neighbor at 90*, then close the angle to 45*. You'll see that the cope no longer matches the profile and opens up the joint.

[James Mudler]

I was cutting crown this past weekend. I found this to be very useful.

http://www.dewalt.com/us/articles/ar...odworking&ID=2