Traditionally the larger metal squares, like the rafter square, were thought of as carpenter's tools. In contrast, smaller wooden or metal ones were more likely to be found in the joiner's or cabinetmaker's tool kit. However, that line was blurred many years ago and today the well-equipped woodworker of almost any stripe finds many uses for both large and small squares.
Hand squares have been used for most of recorded history. Many handmade squares survive from earlier eras and, in a sense, the handwork ethic is still honored; even today hand squares are more likely to be crafted of expensive woods and admired as much for their ornamental appeal as their practicality.
I've included several distinct varieties under the heading of hand squares, including the try square, the speed square, and the combination square.
Try Square. A fixed ninety-degree angle is formed by the thin steel blade and the thicket stock, which is often made of wood. The try square is used for checking (that is, “trying, thus the name), for establishing that a cut or joint is true or square. It's also used to mark cutoff lines or as a straightedge to determine whether a board has warped or “cupped.”
Try squares come in a range of sizes, with blade lengths varying from two to twenty-four inches, depending upon the age of the tool and the purpose it was intended to serve. Machinist's or engineer's try squares are made entirely of metal and are smaller in scale.
The try square is typically put to use in this way. Lay the tongue flat upon the workpiece, then slide the stock flush to the edge of the wood. Thanks to its thinness, the tongue can then be used to scribe an accurate line on the piece to be cut or shaped. Try squares, both new and old, are often tools of great beauty, with blades of fine steel, iron, or brass, with stocks of rosewood, ebony, or other hardwoods. The blade and stock are sometimes fastened together with decorative rivets.