Router (tool)
For the device used in computer networks, see router
A router is a power tool that spins a cutting bit, at very high speed, from a flat base with a motor above it. The bit rotates at much higher speed than the bit in most drills, as the purpose of the router is not principally for cutting holes, but rather for cutting grooves or complex shapes in surfaces, or for smoothing or shaping the edges of a sheet of material. Routers primarily are used on wood or plastic.
Standard, plunge and edge
The first power routers allowed adjustment of the depth of cut, but, if their base was parallel to the work, the bit made contact. A newer type, the plunge router, allows the base to be put parallel to the work, and then the bit gradually lowered, as with a drill press. Yet another variant of the tool is the edge router, which tends to be smaller and often can be manipulated with one hand; its bit primarily cuts with its side, and is used for such purposes as trimming laminate coverings glued to countertops.
Table routers
While hand routers usually are used above the work, the router also may be temporarily or permanently mounted to a table, with the bit pointing upwards. The table may be placed on a workbench, or, for some applications, it can be very convenient to have under one of the side wings of a table saw, so the work can slide from being cut to being shaped. Appropriate guards are especially appropriate here, as it is a dangerous tool when not used with care.
Shaper
The shaper is a larger woodworking tool, but essentially a floor-mounted table router. Some permanent routers also may have complex floor mounts, rather like a drill press, which allow the cutting angle to be varied, and perhaps the bit to be moved radially across the work.
Bits
So that different grooves and patterns can be cut, there is a very large variety of bit shapes. Some may be custom-made. To make certain other patterns, it may be appropriate to make multiple passes with differently shaped bits with different depths of cut. For relatively light duty, tool steel is adequate, but tungsten carbide is often preferred; the stress on a router bit is often greater than on most drill bits.