A scroll saw is an electrical table saw that is operated by a foot pedal. The blade is typically a fine-toothed, narrow, straight blade that is not intended for heavy-duty cutting. It is best suited for intricate pattern work and cutting curves.
There are two basic types of scroll saws: parallel arms and C-arms. A parallel arm scroll saw has two arms, each with their own pivot point. This pivot point is a screw near the back of the arm that allows the arm to bend. The bottom arm hooks to the motor, and the top arm runs parallel to the bottom. The two arms connect at the back, near the motor, and move in tandem with one another.
In contrast, a C-arm scroll saw has a single pivot point, usually on the top arm. The other arm remains rigid. The blade arcs a bit as the motor moves the single arm and attached blade up and down.
The choice between which saw to use depends largely on the user. A parallel arm scroll saw is generally thought to create finer cuts with greater accuracy. A C-arm saw tends to move a bit quicker, but the arcing blade can create noticeable undercuts when using thick pieces of wood. Experienced scroll saw users can develop techniques to minimize the negatives of a C-arm saw, and many prefer it for the speed it can provide.
A scroll saw blade is very narrow, usually only about five inches (12.7 cm) long. The width of the blade varies depending on the project, but is commonly around 1/8-inch (.3175 cm) wide. The blade connects to the saw with either cross-pins or clamps at the end of the saw arm.
There are three basic configurations for scroll saw blades. A skip tooth blade has a tooth, then a space, and then another tooth. A double skip tooth has two teeth, then a gap, and two more teeth. A crown blade, sometimes called a two-way blade, has teeth that face up and others that face down. This configuration allows the blade to cut when it comes up as well as down, and can cut down on splintering on the underside of the project. Spiral blades are twisted so that teeth are on all sides of the blade. In addition to these basic designs, there are also specialty blades that are coated to cut metal or glass.
Scroll saws come in a variety of sizes, usually defined by the throat, or the area between the blade and the motor in the rear of the machine. The larger the throat, the larger a piece of wood it can accept. Most hobbyist saws have a throat about 12 inches (30.48 cm) long, while industrial models can nearly triple that distance.