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How to Cut a Miter Joint

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How to Cut a Miter Joint


If you want to hide the end grain of a board, a miter joint is the joint to make. Miter joints are used for picture frames, door and window trim, and around openings. Miter joints are weak joints--probably weaker than butt joints. Miter joints are a form of butt joints, with the angle at the corner halved between the two pieces being joined.


Choose your method. For best results, use a power saw. The second best way is with a quality miter box and backsaw-or a combination saw that has 8 or more teeth to the inch. The most common miter joints are cut at a 45-degree angle and joined for a 90-degree corner. However, you can vary the angle to any degree you want (especially with a power saw and miter gauge) to fit the project. Example: a hexagon that requires 30-degree cuts. NOTE: For most interior molding situations such as baseboard and crown, etc., you should not miter the inside corners. It won't fit right and miters tend to separate in these situations. For inside corners, you should learn a technique called "coping." This is not difficult (do a search for instructions).


Select the angles. Set the miter box at the angle at which you want to cut the wood. The instructions that come with an adjustable miter box will show you how to set the angles. In a regular miter box, you may be limited to 45-and 90-degree cuts.


Set the piece of molding that will mate to an adjoining surface firmly in the box and then cut off an inch or two. The reason for this is to get a clean, finished end with which to work. Take the piece of wood and set it in position on the item on which you are working, at a point where you want the end of the molding to fall.


Mark the cut-off point onto the wood. Position the wood in the miter box so that when you make your second and final cut the saw will just follow and obliterate the mark. When marking your boards, there is no need to draw a line across it. You simply need to make a "v" mark. The tip of the "v" represents your cut point. Then before cutting, bring the blade down to the wood and line up the mark.


If you cut the miter too long you can trim it. It is better to cut the stock too long because if you cut too short you have to start over again.


Cut and fasten the mating pieces. Cut the other mating pieces the same way as the first one. When all the pieces are cut, fit them together and nail them in place on your cabinet or bookcase, or glue and nail them together to make a picture frame. A good tool for nailing the pieces is a pneumatic brad nailer.


If the brads do not set below the wood surface, set them with a nail set. Then fill the holes with wood putty and stain or paint the putty to match the wood.