Routers: key characteristics
The collet tightens to grip the shank of the bit being mounted in the router. Many mid-size routers come with both 1/4" and 1/2" collets, so they can work with both 1/4"- and 1/2"-shank bits.
Fixed: The standard base, with knobs on either side for holding and guiding the router. It also can easily be mounted to a router table.
Plunge: The base mechanism allows the rotating bit to be lowered a set distance into the stock to make stopped grooves and dadoes, as well as mortises.
D-handle: Instead of two knobs, as on the standard base, there's a knob and a D-shaped handle that provides pistol-grip control and a locking on/off trigger power switch.
Some routers are equipped with variable-speed adjustment features, which means that the speed at which the spindle rotates can be adjusted to work safely with bits of different diameters. (Larger bits need to be run at a slower speed than smaller bits.)
Laminate/trim routers: These machines, which typically have smaller motors and 1/4" collets, are easy to control and ideal for small jobs such as trimming or finishing laminate edges.
Compact routers: They're smaller than their mid-size cousins, but with 1 to 1-1/4 hp, compact routers have more power than trim routers. They provide great control and enough power for many workshop tasks, including edge forming, mortising and freehand routing. They usually have 1/4" collets.
Mid-size routers: They typically have 1-3/4 hp to 2-1/4 hp motors and come with 1/4" and 1/2" collets. Their power and versatility make them a workshop staple, as they can be used both for handheld and table-mounted routing.
Large routers: Typically equipped with 3 hp to 3-1/4 hp motors, these routers are built to handle heavy-duty routing work.