A miter box made of wood (usually beech) or plastic is an inexpensive way of making sure the finish cuts you make with your handsaw—both forty-five-degree miter and ninety-degree cuts—are true. Lining them up perfectly without a miter box is tricky, and when it comes to fitting the pieces together, the miter box more than proves its worth.
In the compact workshop, the miter box has one signal advantage over the powerful miter saw that has become the rule for most professional carpenters these days: It weighs only a few ounces, is smaller than a shoe box, and can be set up on your bench, ready to go, in about the time it takes to pull a handkerchief from your back pocket.
The tool has been in use for centuries, in more or less the same configuration – an open ended wooden box, with slots cut into the sides to guide the saw. Elaborate versions are available with infinitely adjustable angles and ball bearings and metal superstructures, and they’re worth the money if you find you use a miter box frequently. For its occasional convenience, however, I’d recommend having a basic model within easy reach. They’re handy for molding work, frame-making, and a multitude of other ad hoc cutting tasks in the workshop. Don’t forget to rest the piece to be cut atop a piece of scrap wood. That will greatly increase your miter box’s life expectancy.
Making a clean right-angle cut doesn’t take the hand of a craftsman, but miter cuts are different. I’ve done them and you probably have, too; if so, you probably agree that even standard 45-degree cuts are difficult to line up perfectly and not worth attempting freehand. Out-of-the-ordinary angles are even trickier, but you needn’t abandon any notions of making such cuts, since there are lots of devices available to assure that forty-five-degree or other angle cuts are true.
The miter box is one such tool. In one or another of its guises, the miter box has been in common use for more than three centuries. At its simplest, it is a trough-like wooden box, open at the ends, with slots in the sides. A handsaw (often a backsaw) fits into the slots which act as guides to keep the saw on line, making miter cuts accurately and quickly.
Metal and plastic miter boxes are available, too, some even adjustable for compound miters (angle cuts that are more or less than 90-degrees from the vertical as well as the horizontal plane of the stock). The simpler wooden boxes have a limited number of guides cut into the sides (forty-five, ninety, and one hundred and thirty-five degrees at a minimum), but more expensive models adjust in quite precise increments, allowing you to cut almost any angle. Top-of-the-line models have bearings for smoother sawing and grips to hold fast the workpiece that is being cut. Many models come with a built-in or matching saw, either a backsaw or a purpose-made frame saw with interchangeable blades.
Miter boxes (or their powerful brethren, miter saws) are invaluable for molding work, frame-making, and other tasks requiring tight angle-cut joints. If you can use a handsaw, you can use a miter box; it’s really that easy.
I see many fewer professionals carrying their miter boxes to the job these days than I used to only a few years ago (thanks to the power miter saw). But many traditional woodworkers, professional and amateur alike, still swear by the feel, control, and even the familiar reassuring sound of the backsaw at work in the miter box.