Wood Routers: Types, Bases, Bits and How They Cut

A router is a motor with a collet on its spindle, mounted in a base that sets how far the bit projects. It cuts with the side and end of a spinning bit as you move it over the work — or, mounted under a table, as you move the work past it. Bosch's manual for its 1617 series lists collets for 1/4 in, 3/8 in, 1/2 in and 8 mm shanks; the bit you fit decides the cut.

• A router table is a table with the router hung upside down beneath it, so the work moves instead of the router: router tables.
• Router bits are the cutters, sold by profile, cutting diameter and shank size: router bits and the bit profile chart.
• A router plane is a hand tool — a blade held in a wooden or metal body for levelling the bottom of a groove — and has no motor: the hand router plane.
• A shaper is a stationary machine with a heavier spindle and cutters that mount on it: the shaper.
• A CNC router moves the cutter by computer control. It is a separate machine and is not covered in this series.

Bosch's 1617EVS is a typical mid-size machine, and its published figures show what a specification sheet covers: a 12 A motor running at 8,000 to 25,000 rpm, a 1-5/8 in fixed-base depth range, a 3-3/4 in base opening and a 2 in sub-base opening, 8.3 lb. The opening matters more than it looks: Bosch requires the cutter to be at least 1/4 in smaller than the opening it passes through. Current and horsepower describe the motor, not the cut; they are not a measure of how well a router routes. What to compare between routers, and what makes a sensible first one, is set out in choosing a router.

• Motor and speed control. Single-speed or variable; the dial settings are the router's own — see router speeds.
• Collet and nut. A slotted sleeve that grips the bit's shank; the shank must match the collet fitted. 1/4 in, 8 mm and 1/2 in are not interchangeable.
• Base and depth adjustment. Sets how far the bit projects below the sub-base; fixed and plunge bases do it differently.
• Sub-base. The plate that rides the work, and the one most template guides fit into — see jigs and templates.

Every bit carries its own maximum speed. Freud and Bosch's Colt manual say never to run a bit faster than that rating; Bosch's 1617 manual is stricter and asks for a bit rated at least as fast as the highest speed marked on the router. Larger bits run slower: Freud rates its 1-3/8 in rabbeting set at 16,000 rpm against 24,000 for many of its smaller bits, and says bits over 1-1/2 in diameter must only be used with the router mounted in a table. The speed chart sets the makers' figures side by side.

Feed direction is the other rule every manual repeats. Seen from above, a handheld router's bit turns clockwise, so the router is fed counterclockwise around an outside edge and clockwise inside an opening. The opposite direction is a climb cut, which Milwaukee and DEWALT warn increases the chance of losing control. Using a router covers setup, feed and passes step by step, and using a router table the same for table work.

A router follows something: a bearing on the bit riding the edge, an edge guide on rods, a straightedge clamped to the work, a template guide in the sub-base following a template, or a fence on a table. Choosing among them, and working out where a template-guided cut lands, is in jigs and templates. Measure from the bit's cutting edge, not its centre, and mark from a reference face as in measuring and marking.

Routers cut many of the joints in this library: the mortises in mortise and tenon work, the pins and tails of dovetails in a jig, the fingers of a box joint on a table, and the rabbets, grooves and dadoes in choosing a joint. Two shop builds are worked out in full: a dado guide and a flattening sled in router projects, and a split fence for a table in router table projects. For holding the work, see clamps and the workbench guide; for planning parts, the cut list optimizer.

• Power off before the bit. Bosch says to unplug the router before installing or removing bits; Milwaukee says to remove the battery first.
• The right shank in the right collet. Bosch's Colt manual warns that a smaller shank can come loose and become a projectile; Milwaukee warns a mismatched collet may break. Never improvise a sleeve or adapter.
• Clamp the work. Bosch and Milwaukee both say holding the work by hand or against your body leaves it unstable.
• Start and stop clear of the work, and hold on. Never start with the bit touching the work; hold the router firmly against start-up torque; never set it down until the bit has stopped.
• Bits within their limits. Sharp and undamaged, no larger than the base opening allows, never run above their rated speed.
• Dust. OSHA treats wood dust as a health hazard. Milwaukee says dust collection can reduce dust-related hazards, and calls for respiratory protection or OSHA-compliant extraction in dusty work: a dust port reduces exposure, it does not end it. Check the bit maker's list of materials before routing MDF or plywood with a bit sold for solid wood.

• Machines: compact routers, plunge routers, router tables, the shaper.
• Bits and speed: router bits, bit profile chart, speed chart.
• Technique: using a router, setting up a router table, jigs and templates.
• Builds: router projects, router table projects.
• Choosing: a benchtop router table, a compact router, a cordless router.