How to Make a Miter Joint

Miter joints consist of two cuts made at equal angles and joined together. Picture frames are made in this way, and both pieces in the miter joint of a picture frame are usually attached to each other. On the other hand, miter joints are sometimes used in trim carpentry, and in this case the molding usually gets attached directly to the frame of the house instead. Only occasionally when one is running molding around an abutment will two pieces of molding ever be attached to each other. The emphasis of this article will be on the assemblage of a four-sided frame, where each piece is attached to another.

Difficulty: Moderately Challenging

Instructions

Things You'll Need:

• Miter box or miter saw
• Molding
• 4 corner clamps
• Electric nail gun
• Small nail set
• Small hammer
• Carpenter's glue

1. Choose your stock of wood and cut the wood into four pieces.

2. Cut each end at a perfect 45-degree angle. You can make each piece the same length for a square-shaped final product, or you can cut the wood into paired lengths to form a rectangle. Make sure the paired pieces are of equal length after the angles have been cut. You can use a simple miter box for these cuts, but a power miter box or a miter hand saw on a swivel base are better choices for this project.

3. Sand each end gently and add a small amount of carpenter’s glue to the face of each cut.

4. Find a flat work surface and place the four pieces of wood in corner clamps. Make sure all four corners are snug and wipe away all excess glue. Tighten the clamps a little bit at a time as you move from one corner to the next.

5. Let the glue dry.

6. Nail the corners together. Make sure the clamps are still in place. You can use brads and a small claw hammer, or an electric nail gun that shoots out brad-sized finish nails.

7. Set all nails all fill the holes with a wood putty that matches the color of the wood.

8. Release all the clamps and lightly sand the finished project, which is ready for a light finish or a paint job.

Tips & Warnings

• If a nail breaks through the surface of the wood, pull the nail back out and insert another nail in a different location.
• Double-check to make certain that your stock of wood is not twisted.
• Miter joints are usually made for decoration, not strength.
• Don’t use a compressor-driven nail gun. They are far too powerful.
• Wear safety glasses when using an electric nail gun.