A pin router is a benchtop power tool that's designed to give a woodworkers a high degree of accuracy and control in pattern and template routing jobs. The cutting blade of the router, called the bit, is cylindrical in shape, usually no more than three inches (7.6 cm) in diameter, and is usually plunged into the face of the workpiece. A template is fastened to the back of the workpiece and a guide pin is used to control the movement of the workpiece so the bit cutting into the workpiece's face replicates the pattern on the template.
There are two basic types of pin router. The first positions the router above the tabletop, much like a drill press, and the bit is lowered into the workpiece. The position of the router is carefully adjusted so the rotating bit will center perfectly on the guide pin, which is secured to the tabletop. The second type of pin router positions the router below the surface of the table, from where the bit can be raised through a hole in the table and into the workpiece. In these routers, the pin is secured to an overhead arm and positioned directly over the bit's center. The best way to control the movement of the bit into the workpiece, in both machines, is to use a foot treadle, so both hands are free to control the workpiece.
A pin router is most commonly be used to cut shapes into the face of a piece of wood stock, and the process is virtually identical, regardless of the type of pin router used, except for the orientation of the workpiece. Where the pin is secured in the table top and the router is plunged down into the workpiece, the workpiece is placed on the table face-up. Where the guide pin is secured to an overarm attachment and the router bit extends upward from a hole in the table, the workpiece is placed on the table face-down.
The template can be a simple outline or an elaborate design, usually designed to accommodate a specific size and shape router bit. Once it's secured to the back of the workpiece, usually with carpenter's double-sided tape, the operator places the workpiece on the table so the guide pin is in contact with the template. The router bit is then raised or lowered into the workpiece the proper distance and the operator begins moving the workpiece at a steady speed, always moving against the rotation of the bit, and keeping the edge of the template in contact with the guide pin.
Dedicated pin routers have been manufactured for that purpose, and at six horsepower (HP) and greater, they are generally more powerful than hand-held routers, which generally are no more powerful than 2.5 - three HP. This is so because dedicated pin routers generally must remove much more stock, often with bits up to three3 inches (7.6 cm) in diameter. Hand-held routers, by contrast, are designed for cutting moldings and other applications where a much smaller amount of wood is removed from the workpiece using bits generally no larger than 1.5 inches (3.8 cm) in diameter. In those cases where woodworkers have set up makeshift pin routers using a pin router jig or a pin router attachment, the tool employed is usually a hand-held router mounted on the underside of a router table, and care must be exercised not to place too great a strain on the router to avoid burning out its motor.