Miter Joints

Miter Joints

Miter joints are used to connect two perpendicular components, most commonly at a 90 degree angle, though they can be applied to joints at varying angles. Miter joints are not particularly strong as they are attached along the end grain, and therefore create a seamless joint that conceals the end grain.  Miter joints are generally used in projects that will not experience a high level of stress, such as frames and moldings, to create a more aesthetic corner. Mitering can be applied to various styles of joinery in which two components are meeting at 90 degrees to hide joinery, or create a more symmetrical corner.

Basic Miter Joint

A basic miter joint is created to join two pieces at 90 degrees, by cutting the end of each component at a 45 degree angle. The two components are then joined using adhesive. Miter joints can be made using hand tools, but it is preferable to use a table saw, compound miter saw, or panel saw to create a cleaner edge for the glue to adhere to. This can be done either by angling the blade on a table or panel saw, or by creating a sled to hold the component at 45 degrees and passing it on a squared blade.

Varieties of Miter Joints:

As a basic miter joint is fairly weak and cannot withstand a great deal of stress, varieties of this joint can be used to strengthen it for application in projects that will experience higher levels of stress.  In addition to using hardware to strengthen a miter joint (eg. Nails or screws), there are a number of different mitered joinery methods that can be applied.

Splined or Biscuited Miter Joint

A miter joint can be strengthened by adding a key or spline. By cutting a groove into the mitered corner and inserting one or more splines (cut to slightly above the size of the groove and subsequently cut, planed or sanded flush with the material), or a biscuit, the corner joint is strengthened and held secure by both adhesive and wood components. Biscuits are a convenient option to add structural integrity to the joint, while splines can be modified to fit the size and shape of the project, or to add decorative elements to the joint.

Mitered Half Lap

The mitered half lap is a combination of basic miter and half lap joints, wherein the half lap is cut at a 45 degree angle, to create a mitered joint on the front face, while maintaining a greater surface area for adhesive.

Locked Miter

Router bits can be used to create an edge profile that is mitered on one side and has a cope and stick locking mechanism on the interior edge. This maintains a 90 degree joint but adds stability.