Routing for Dummies

Think “versatile” when you think “router.”  “Having many uses or applications” is a perfect definition of the router, a tool that is basically a high-speed, high torque motor with handles – sometimes.  With or without handles, the router can be a challenge to learn to use properly, but its broad utility makes it a worthwhile skill set to master.

Routers come in several flavors and sizes, from one-handed trim routers to large plunge routers; you’ll want to own at least a couple for different purposes (I have three.)  Size matters, as larger, bulky tools can’t be controlled easily when performing delicate tasks like trimming plastic laminate for a counter top.  Smaller routers are under-powered for plowing large rabbets or carving dovetails with a jig.

Plowing large rabbets?

A bit of router terminology will help with understanding the benefits, and pitfalls, of router usage.

RouterSpeak 101

Routing v – generally,  removing wood with a power router; specifically, removing wood from the workpiece away from the edge.

Edge shaping v – removing wood from the inside or outside edge of the piece.

Dado cut n – a square channel with two sides and a bottom cut across the grain.

Plough (plow) cut n – similar to a dado cut but cut with the grain, sometimes called a gouge or a groove.

Rabbet cut n  – a dado or plough on the edge of a  board and having only one side and a bottom.

Rabbeting v – the act of cutting or joining a rabbet joint.

Rabbet joint n – a joint formed by fitting together rabbeted boards.

Tear-out n – wood which splinters resulting from flaws in the grain, cutting too fast, cutting across the grain at a corner, or a dull bit.

Bit n – the replaceable part of the tool that actually performs the cutting.  Bits come one-piece combining shank, cutter and bearing, or arbor type with the cutter and bearing removable.

Dovetail joint n – a joint  formed by joining a flaring tenon and a mortise, usually at the corner of a box.

Tenon n – the male half of a mortise-and-tenon joint.

Mortise n – the female half of a mortise-and-tenon joint.

Pilot bearing n – a wheel mounted on a bit shank which rides on the edge of the material being routed to control the cut.

Edge guide n – an accessory attachment that can be adjusted to set the precise location of a cut.

Plunge v – to enter the wood surface with the router running to start a cut in the middle of a surface as opposed to from the outside edge.

Through cut n – a plough or dado which extends from one workpiece edge to the other.

Blind or stop cut – a cut that ends before reaching the outside edges; a half-blind cut begins at an edge and stops before reaching the opposite edge.

MEGO Syndrome n – “My Eyes Glaze Over” with all this terminology.  Enough already.  I’m going blind.  Stop.  Cut.

A Word on Safety…

Concentrate.  Elsewhere I write about Safety (with a capital “S”) as resulting from un-common sense.  In other words, if Safety was “common” sense, there would never be any disfiguring or dismembering accidents with power equipment.  Unfortunately, Safety is an art, a discipline and a skill all unto itself.  It’s not innate; it has to be practiced and learned by rote.  Even then, “…time and chance happen to them all.”  Kind of like that other thing “happens.”

A router, like a chain saw, is a high-speed, high torque, noisy, sharp cutting machine that with just a little inattention can ruin not only your beautiful project but your whole day.  Set-up and planning for each cut are important.  Ensuring a distraction-free and comfortable work space is critical.  Hearing protection and eye protection (from flying wood and dust) are basic requirements.  If you wear corrective lenses, wear them and use bright light to clearly illuminate the work area.

All these factors and more contribute to your uncommon sense of Safety.  Concentrating on the task at hand to the exclusion of intrusive thoughts and distractions goes a long way to safe and successful router use.

Direction of Cut

Universally (I hope) router motors spin clockwise; this does not change with the Coriolis effect south of the Equator.

The direction of travel while holding the tool against the work or guide (known as thrusting the tool) will make your job easy or hard, depending on which direction you choose.  For different circumstances, the direction of travel will change.  The reason is related to the clockwise rotation and the extreme torque of the motor.

It’s said “a picture is worth a thousand words,” so…

In the picture, notice the clockwise rotation of the router.  The router is held (thrust) against the guide or the work.  To avoid kickback, always thrust the tool in the same direction that the leading edge of the cutter is moving.

The idea is to “chop” down into the stock from the “top,” rather than gouge out the wood from the bottom.  This is so much more efficient for the tool and easier on you to control the tool.  Study the drawing and you will understand the circumstances when you will travel clockwise or the reverse, whether it’s a curve, a straight shot, an inside or an outside edge.  And only 109 words.

Feed Rate

Force feeding and standstill feeding are to be avoided.  Only experience (the best teacher) will teach you proper feed rate (speed of travel) for the species and condition of the wood you are carving.  Force feeding is moving through the stock too rapidly, resulting in overworking the cutter and the motor and reducing your ability to control the machine.  Standstill feeding is the opposite.  Moving too slowly causes the cutter to wander and bounce around in the cut causing rippled sides, glazing and even burning of the wood and cutter removing the metal’s temper and sharp.

Some machines have features like variable speed control and “slow start.”  These perks give you more control by reducing torque on start-up, and the ability to select a speed somewhere between off and max power.

Correct feed rate “feels” right.  The cutting feels effortless and  smooth; the debris coming from the cutter looks like uniformly sized small chips, and there’s no splintering.  Proper depth of cut also effects a good rate of feed…

Depth of Cut

Depending on the wood and your planned finished cut size, one pass with a sharp bit might be all you need.  On the other hand, if the finished groove is wide or deep, multiple passes are recommended to minimize wear and tear, effort, blood, sweat, and tears.

A rule of thumb:  The smaller the diameter of the cutter and the shallower the finished cut, the fewer passes are required (but, make a least one…)  As the bit size and the wood hardness increase, the maximum advisable depth of cut per pass decreases.  Make multiple successive passes to a depth not exceeding 1/8 inch into new wood until the desired width and depth are achieved.

Cutters a.k.a. Router Bits

When it comes to selecting the cutter that’s  going to do the job you need it to do, there is no more important quality than sharpness.  Router bits are spendy, yet cost only a few bucks to have professionally sharpened.  Invest in sharp bits and reduce about 80 percent of potential problems that arise when working with a router.  Like any razor sharp object, however, handle bits with care and always unplug the tool when changing or adjusting bits.  A little care and presence of mind goes a long way to preserving fingers.

A minimally helpful article at eHow entitled “Using a Wood Router” claims, “There are between 20 to 30 (sic) different diameters, shapes and sizes to choose from, but making sure the bit is sharp is of utmost importance.”  Thank you for verifying what I just said, but a cursory glance at the Woodworker’s Supply Inc. Big Book lists at least 180 different cutter profiles.  Multiply this number by at least ten to arrive at a round number for all the profiles, shaft sizes and cutter diameters available for your woodworking pleasure.  Heck, one set alone has 66 pieces!  (I’m sorry, I can’t resist:  the same article contained this gem:  “Router bits have a multitude of infinite adjustments, and can go deep or shallow.”  Hmmm.)

Pilot bearings serve two purposes:  If the bearing is on the bottom, edge shaping is a breeze.  Just pull the router (rather than push it – for more control) along as the bearing rides  the edge.  If the bearing is on the top of the bit, the bit can follow a template on top of the workpiece to duplicate an edge or shape.  Plastic laminate is easily trimmed with a flush trim bit and pilot bearing mounted on a one-handed (no handles) trim router.  Like bits, bearings need to be cleaned of resin and residue buildup occasionally so they continue to spin freely.

There are myriad cutter profiles for every conceivable routing job:  creating raised door panels, tongue and groove joints, coves, V-grooves, keyhole slots, straight, dish, round nose, core box, all kinds of beads, flutes, bevels, chamfers, ogee, Roman ogee, dovetails, hinge mortising, T-slot, round over, slotting, glue joint, finger joint, box joint, stile and rail, quarter round, window sash, rabbeting, door lip, lock miter, pattern making, lettering, plunge cutting, multiform, combination, double edge radius, corner round, veining, and something called an insert finger pull bit, which sounds like an “insert finger – pull” bit to me.

Router bits are available in High Speed Steel (HSS) and a superior version which uses carbide steel on the edge of the cutter.  You get what you pay for:  carbide stays sharp longer and is a much harder steel.  Both can be sharpened at the same cost.  If you hit a nail imbedded in the wood, unfortunately, neither carbide nor HSS will withstand the damage.  That’s the Voice of Experience talking.

A Router for Every Job

I’ve mentioned a couple of the types of routers available to the pros and D-I-Yers.  Here are a few more:

A trim router kit contains some very cool accessories that greatly expand its utility.  An offset belt-driven base attached to the motor allows you to move the cutter very close to a vertical surface like the end of a counter top where it meets the wall.  Another specialized base can be set to mount the motor and cutter at an angle.  I haven’t found a use for this feature yet, but it’s still cool.  I use a trim router to free-hand cut hinge mortises; it’s easy to control and saves time it takes to set up a jig and bushing on a full-size machine.

Accessories

Some routers come with accessories; others let you pay extra for stuff you need, like an edge guide, a trammel point (for cutting perfect circles), a contour finger, and guide bushings for following a template such as for making butt-hinge mortises in a door.

Additional specialized accessories include a dovetail fixture, lettering template and a pantograph for custom reproduction of any traceable design.  There is a device called a Router Crafter by Craftsman that enables your router to be used like a lathe to fashion table legs, reeding (parallel beads), fluting (parallel grooves), rounded square stock, contours and spirals without the muss and fuss of learning to use wood-turning chisels and maybe yanking a bald spot on your head when your hair gets caught in the rotating machinery.  If it’s not one thing, it’s another…

An edge guide is a basic accessory you need, but a clamped straight edge is a reasonable substitute.  Use a perfectly straight board or metal straight edge for best results.   Some edge guides convert to circle guides, so do double and triple duty cutting and rabbeting circular cuts.  You can also fabricate jigs, templates and patterns to accomplish just about any task with a little thought and ingenuity.

Technique

Clamping the workpiece makes for a stable work surface, which is important when you are working with high-speed and powerful torque forces.  Sometimes you see rubber grip mats used to keep the work from moving, but I prefer the solidness of a clamped piece of wood.  Clamping smaller pieces can be accomplished by using blocks abutting the work piece that are clamped down, boxing it in.

Some routers have an eye shield built-in at the base of the tool; it’s usually transparent, which implies it’s good practice to watch the progress of your cutting operation as you move the router along the work.

No eye shield?  Wear eye protection, but watch the cut as it progresses.  This will focus your attention on the task at hand and you will be less inclined to make a mistake.  On some tools the throttle switch can be locked on (for long cuts) removing one other thing to have to think about while you’re concentrating.

To avoid tear out at the corners, which is not uncommon, make a cut at the far corner first, going at the corner from the “wrong” direction.  Just clip the corner, then start your cut at the correct end of the board; when you come to the far corner, the wood will already be removed, avoiding tear-out.  You can also use a piece of scrap wood at the corner to keep the cut going past the corner without ripping out the grain at the end of the good board.

I like to keep a test board handy when doing multiple repeat operations with the router.  I can test the depth of cut, location of the cut, etc. until I get it right.  Then I use the (correct) parts of the test board to set the tool up for subsequent identical cuts.  I just drop the bit down into the groove on the test board to the correct depth, and lock it in place.  This also is helpful to test round over cuts so I don’t accidentally make the shoulder detail too shallow or (worse) too deep.

Review the material above about feed rate, depth of cut and direction of cut to improve your confidence and technique using your new (or your newly dusted off) toy.  Dust off the manual for your router, too, and read up on how to adjust the cut depth, speed control and collet (what’s a collet?) nut.  Soon enough you’ll be routing like you were born with one in your hands.

Uh, that’s a scary thought.

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