Replies

1. 
   snap pea | Oct 28, 2008 04:26am | #1

   If you happen to have access to Fine homebuilding #162 (May 2004) an article by gary Katz that addresses the situation you are asking about is on page 140. Or you could try searching for it on Finehomebuilding.com. The title is "Crown Molding around a cathedral ceiling" If I understand you're question, that article might help.

2. 
   AitchKay | Oct 28, 2008 04:31am | #2

   Yeah, a bunch of posts exist on this concept. I'll let the e-pros link you to them.

   But unless you want to mill custom molding for the rake (sloping) sections, cut a small, triangular transition piece.

   That's because you can't miter in two planes at once and keep the same profile. So you break the operation up into two adjacent steps:

   One end of the transition piece is mitered horizontally to the level trim. The other end is mitered to the slope.

   Working from a level run and going up, this transition piece comes to a point at its top edge, so everything fits tight to the ceiling.

   The level, transition, and rake pieces all meet at this same point, and their profiles all match up.

   Working from the top horizontal run of a shed roof, and going down, the transition piece comes to a point at its bottom edge.

   Once again, the level, transition, and rake pieces all meet at this same point, and their profiles all match up.

   AitchKay

3. 
   FatRoman | Oct 28, 2008 05:41am | #3

   This post has a couple of pics that might help you out.

   http://forums.taunton.com/tp-breaktime/messages?msg=93559.36

   'Man who say it cannot be done should not interrupt man doing it' ~ Chinese proverb

   View Image

1. 
   AitchKay | Oct 28, 2008 04:50pm | #5

   Bingo, FR,That's the transition block I was talking about. Thanks for the link to the pic.AitchKay

4. 
   JoeBartok | Oct 28, 2008 03:18pm | #4

   Spike, here are some links to the theory on how to intersect the crown at rake walls or vaulted ceilings without a transition piece:

   Thread at JLC Forums ... Polygon Rafter Tables

   My web page detailing the theory resulting from the discussion. I made bristol board models to test the math ... Compound Rake or Prow Roof Crown Molding Angles

   Web page by Sim Ayers. There are links to calculators and he also tested the math by making models using crown molding ... Crown Molding Angles by SBE Builders

    

   Joe Bartok
1. 
   AitchKay | Oct 28, 2008 05:05pm | #6

   Hey, Joe,All of that goes right over my head! Can you add some narrative text to explain what you are trying to accomplish? From one of the pics it looks as though you are changing the spring angle of the level runs to accommodate the rake runs. That can work with very low slopes, but the look starts to deteriorate at about 2/12, IMO.In other pics, I couldn't really tell what was going on... A lot about various different polygons...The traditional way is to grind custom knives and make a stretched-out profile for the rake sections. But that usually isn't worth the expense.AitchKay