Crown molding
1582810
225900502
2008-07-15T22:48:25Z
Rhvanwinkle
3603172
'''Crown molding''' encapsulates a large family of moldings which are designed to gracefully flare out to a finished top edge; generally used for capping walls, [[pilaster]]s, [[cabinet]]s; used extensively in the creation of interior and exterior [[cornice]] assemblies and door and window hoods.
In recent times, crown moldings have generally made their appearance as mostly decorated [[plaster]] or [[wood]]en trim where walls meet [[ceiling]]s.
== Installation ==
Crown molding is typically applied along the seams where ceiling meets wall. Usually it is not placed flush against the wall nor against the ceiling. Instead, when viewed from the molding's end, it, the ceiling, and the wall form a triangle. This adds a difficulty to the installation process, namely the need for complex cuts to form corners where two walls meet.
There are two common ways to fashion inside corners. One is to use a [[miter saw|compound miter saw]] to cut the ends of the corner pieces along two axes simultaneously. The other, called [[Coping (joinery)|coping]], is a two step process, first to cut a simple miter and then to use a [[coping saw]] to undercut the miters.
Another way and the easiest way to install crown molding is by using crown corner blocks. This eliminates the need for miter cuts or coping; the molding is installed with a straight flat cut.
Many different companies now manufacture crown molding in materials such as plastic and foam. These typically are offered with corner blocks, and are popular with [[Do it yourself|DIY]] [[home improvement]] enthusiasts.
== Angle calculations ==
The calculation of the angles to cut crown molding is affected by the angle that the plane of the molding makes with the walls. Crown molding is usually sold in either a 45 degree or 38 degree format, so correct angle determination should be made before attempting to cut the molding.
The formula used to calculate the angle to make the cuts in a spreadsheet is:
* Cell 1 - slope a (in degrees!)
* Cell 2 - A15*PI()/180
* Cell 3 - slope b (in degrees) (note: slopes a and b will be the same when figuring crown molding)
* Cell 4 - C15*PI()/180
* Cell 5 - wall angle (in degrees)
* Cell 6 - E15*PI()/180
* Cell 7 - ATAN((COS(B15)*TAN(D15)+SIN(B15)*COS(F15))/SIN(F15))
* Cell 8 - G15*180/(PI()) = [[Miter joint|Miter]] Angle (in degrees)
* Cell 9 - ATAN((COS(D15)*TAN(B15)+SIN(D15)*COS(G15)/SIN(G15)))
* Cell 10- 90-(I15*180/(PI())) [[Bevel]] Angle in degrees
To simplify the cutting process, [[Computer software|software]] can be used to accelerate the calculation process.
== External links ==
* [http://www.installcrown.com How to install Crown Moulding], a full site dedicated to installing crown molding with Angle calculator.
* [http://www.issi1.com/corwin/crown.html A Web-based mitre angle calculator]
* [http://www.woodweb.com/knowledge_base/_Spreadsheet_Calculation_Program.html Spreadsheet form] using [[Microsoft Excel]]
[[Category:Woodworking]]
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[[Category:Walls]]