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  Cutting Crown Transitions for Cathedral Ceilings  
One of the things I enjoy most about my craft is that I'm constantly learning new carpentry techniques. I used to shy away from installing crown on cathedral ceilings, in fact, I'd just tell clients that it looked terrible so I wouldn't have to hassle with doing the job. But during a JLC LIVE dinner at a show not long ago, several of us were talking about intalling crown on a cathedral ceiling. Mike Sloggatt said there was a way to cut a transition for the corner but it had been so long since he'd last done it that he couldn't remember the steps. Jed Dixon said something about one side being cut one way and the other the opposite way. Whatever that meant, the idea stuck in my head. Timing is everything. Just a few weeks before, I'd learned from Joe Fusco how to use two different sizes of crown for running cathedral ceilings (a smaller size for the gable rake), and he also told me to cut the gable pieces RIGHT-SIDE UP in my miter saw, but more on that in a minute. It wasn't long before another cathedral ceiling reared it's head, and this time, instead of talking the people out of crown molding, I was eager to work on the problem.
The pie-shaped transition piece changes the direction of the crown molding from horizontal to slope, and it also changes the plane of the molding. The cut on the right side of this transition is a normal 45° inside corner cut. But finding the angle for the left side, which is an outside corner, requires a little math.
Start by measuring the slope of the ceiling.
Because the transition has a normal inside-corner cut on one end, subract 90 degrees from the slope of the ceiling.
Because the angle finder was placed against the ceiling and not upside-down on the bottom line of the crown molding (the line that the crown follows), you must also subtract 180 degrees from the result on the angle-finder.
Math isn't my best friend, so here's how I double-checked to be sure I understood the problem. Using two short pieces of 1x, I marked a long level line out of the corner, then made another line parallel to the ceiling so I could hold the angle finder on the real line of the crown molding.
If you've ever installed crown on a tray ceiling, you know that the top edge of the crown must be ripped to follow the slope of the ceiling.



That's the first step. You can use a portable plane to take off the back edge of the crown, but for a large room, a table saw works better.

Don't be stupid and attempt to
free-hand this cut.


Build a sled and attach it to the fence on your saw.
Keep your hands away from the blade, and never push HARD from any direction toward the blade. Let the saw do the work.
When the cut is nearly complete, use a push stick to keep your hands away from the blade.
Cutting the miters on the tranistion is the easy part. The insider corner is a normal 45° cut--so make that cut first, with the crown molding upside down in the saw (the ogee profile on this Windsor One crown should be positioned at the ceiling--so in this picture the molding is upside down in the saw, as it should be for the inside corner cut). Remember, when you cut an inside corner, the LONG POINT is always against the fence (see Mastering the Mitersaw, Part I).


Next, cut the outside corner for the transition, but remember to TURN THE CROWN RIGHT-SIDE UP!! (whenever you cut crown going up a gable or rake, the material must be placed in the saw right-side up). That miter is half the angle of the ceiling. And when you cut an outside corner, the SHORT POINT is always against the fence (see Mastering the Miteraw, Part I) Keep your hand at the back of the fence so you can creep the material up to the blade.
Cut the piece about 1/8 in. short (take the tip off the top of the miter) so the transition won't interfere with the horizontal and gable-rake pieces meeting each other.
Here's a mock-up example. Notice how the tip of the transition is a little short, which allows the joint to close up tighter.
For outside corners, I haven't figured out a better alternative than using a pendant. If someone out there knows a better way, please let me know!
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