How to Cut Odd Angles for Crown Molding Using a Compound Miter Saw
Written by Milan Jara on 22nd Aug 2022
Cutting awkward crown molding angles isn’t easy, especially for beginners. Here’s how to cut odd angles for crown moldings using a compound miter saw.
Let's face it: cutting odd crown molding angles isn't the most straightforward job. Each crown molding corner requires you to cut two compound angles—a miter angle across the molding’s face and a bevel angle across the molding’s edge or end.
The edges of the two cuts meet to form the joint of the crown molding at that corner, and you must do both angle cuts correctly for the joint to be smooth and fully closed.
The angles are called compound angles because you must cut them simultaneously to complete each joint for a smooth crown molding installation.
Since it isn't always easy, especially for beginners, we prepared this handy guide on how to cut odd angles for crown molding using a compound miter saw.
What You'll Need to Cut Odd Crown Molding Angles
- Crown moldings. To be double sure that you are doing the right thing, you can buy some sample crown moldings to try out first.
- Compound miter saw that cuts both miter angles and bevel angles. You must always use the correct settings on the power miter saw to achieve tight-fitting joints.
- Compound cut conversion table.
- Analog protractor or digital protractor, if available.
- Small flat surface, like a piece of wood several inches long.
- Scraps of wood. These are optional and valuable if you don't have a protractor.
- Bevel gauge.
Steps for Cutting Weird Crown Molding Angles
Follow the steps below to make accurate crown molding cuts for awkward angles.
1. Determine the Spring Angle
The spring angle is the angle between the wall and the crown molding.
To obtain the spring angle, place the bottom edge of the crown molding on a flat surface and use a bevel gauge to measure the angle formed between the flat surface and the edge of the molding.
Place the bevel gauge against a protractor and read the angle. Most crown moldings on the market have a 38° spring angle, while some have 45° and 52°. For this post, we will use a 38° spring angle.
Alternatively, you can use a trial and error method to determine the spring angle.
Cut several triangular pieces of wood to function as test blocks to see which one blends seamlessly with crown molding. The one that fits seamlessly is the one that matches the spring angle.
2. Determine the Wall Angle
To determine the wall angle, lay the bevel gauge into the corner and read the angle on the protractor. To obtain the miter cut, subtract the wall angle from 180° (angle of a straight line) and divide the result by two.
For example, if the wall angle is 88°, the miter cut will be (180° - 88°)/2 = 46°.
3. Determine the Miter Angle
Use the compound conversion table to find the miter angle. The table shows values used for cutting crown moldings as they lay flat on the miter saw.
Find the miter cut column and scroll down to the miter cut obtained above (46°). Go to the correct spring angle column (38°as selected earlier) and scroll down to where it corresponds with the miter cut (46°).
In our case, the miter angle will be 32.5°.
4. Set the Miter Saw to Match
Once you have obtained the miter angle, set the miter saw to match this angle.
5. Determine the Corresponding Bevel Angle
Using the compound conversion table and following the same process as the miter angle, determine the bevel angle.
The miter cut and spring angle will remain the same. In our case, the bevel angle will be 34.5°.
6. Set the Miter Saw Bevel
Set the bevel of the miter saw to match the bevel angle you have obtained above (34.5°).
Quick notes:
- If you have a purpose of a baseboard (which doubles as a digital protractor), you can quickly obtain the spring angle directly from the crown molding. Rest the bottom of the molding on a flat surface and read the angle that displays on the screen when you place the miter gauge against the setup. The spring angle saves into the memory of the miter gauge.
- Use the miter gauge to read the wall angle by placing the gauge into the corner.
- The miter gauge will help you calculate the miter angle, so you can set the saw to match.
- Use the miter gauge to calculate the bevel angle, then set the miter saw to match.
