Using a Miter Box

Anyone that has been faced with the need to create a good joint either into or around a corner, knows that just having one piece of material butting up against another does not produce a neat job. Instead you need to cut angles into the material, so that both pieces adopt the shape of the interior or exterior angle forming the corner; requiring you to cut 45 degree angles through the material.

Using a miter box makes cutting these angles a lot easier. Miter boxes are most commonly associated with cutting timber, but they are also regularly used to cut plastic pipes, conduits and coving of all materials; as well as metals.

What is a Miter Box

A miter box, or block, can best be described as an open-ended rectangular box without a top; or, in other words, a rectangular base with two sides to it. The sides have channels cut into them, typically at 45 and 135 degrees on each side; there will also be a channel on both sides cut at 90 degrees.

The channels are usually designed to accommodate the width of a tenon backsaw; although you can also buy ones suitable for hacksaw blades. The shapes of the cuts they create are referred to as miters.

Square, Rectangular or Round Stock

To cut a material in a miter box it is essential to measure where to make the cut accurately; and if it is rectangular in its cross-section that you have it the correct way up. Then, by placing it in a miter block and aligning the tenon saw in a 45 degree angle on one side and a 135 degree angles on the other - simply saw through the material.

Take the other length of material and insert it into the miter block in the opposite direction, align the saw blade as before and cut through the material. You will then have two lengths of the material with correctly angled cuts that can create an internal or external angle. If you need to make a straight cut at 90 degrees through a material, using the 90 degree guides in a miter box will help you get a perfectly ‘square’ cut through it.

Miter Box Tips

If the material you’re working with is narrower than the width of the miter box, wedge it into place with an off-cut of wood. If the underneath of the material has a beveled underside, pack it underneath so that it can be cut evenly.

Trying to grip a miter box and a heavy piece of timber can be difficult, so securing the miter box in a vice will allow you to just concentrate on holding the piece of timber.

Cutting Coving

Cutting corners into coving is not just a question of measuring and aligning the coving in the miter box. Coving is invariably concave in shape, occasionally convex and hardly ever perfectly round or ‘square’. Subsequently you can’t just measure and cut it. If you put a piece of coving into a miter block you’ll quickly realize there are different ways you could position it.

Each position will produce a different cut that will align into or around a corner differently, but usually not correctly. To correctly cut coving to produce a perfect corner in a miter box you must make sure that the coving sits in the miter box with its back edge flush against the miter box.