Routers

The term router has come to be applied to a number of tools which differ from one another in purpose, operation and appearance. The name is applied most appropriately to the router plane which is in fact usd for "routing out"" a depression in the surface of the work

But there is another group of tools which resemble spokeshaves in outward appearance although they differ in most other respects due to their narrow frequently profiled cutters. Many of these were used by coachbuilders, but a larger version, the sash router, has large profiled cutters bedded like a plane and was used for making bow windows.

Towards the end of the nineteenth century a number of metal routers were developed which aimed at replacing the older wooden routers and were used by carpenters, cabinet makers, and then for circular work on sashes, doors, hand rails, and furniture. Metal routers were seldom used by coachbuilders, they clung to the wooden version until the end. The forerunner of the portable electric router was the Sheffield cutlers "parser", a kind of small bow drill with a bifurcated bit. It was used to cut recesses tor ornamental plates in pocket knives and other tools.

Hand Router

OTHER NAMES: Router plane, depthing router

SIZE: Width: 8-1/2in

MATERIAL; Body: cast metal; Handles; wood

ATTACHMENTS: Vanous cutters guide fence. shoe

USE: To cut grooves, and dados to level, to remove wood waste

The router is most commonly used for cutting dados or grooves in a wooden surface. The router can also remove waste material from rougher cuttings and accurately level recesses in cabinet work or low relief carvings.

The standard cast metal router is most commonly made with an open throat, which gives a clearer view of the work and allows the shavings to be cleared from the housing. The bridge joining the two sides of the throat strengthens the stock and carries a clamp which holds an adjustable rod. An optional shoe for closing the throat is fitted to this rod. This shoe is necessary when working across narrow sections of wood to support the router on the edge of the work, and it must be set flush with the sole of the stock.

Routers are usually supplied with three cutters: 1/4in. and 1/2in, wide chisels, and a V-shaped smoothing cutter. They are cranked to set the cutting edge at a shallow angle to produce a paring action.

Using the cutters

To trim any wide dados, it may be necessary to make more than one pass across the width. The slicing action of the V-shaped cutter gives a smoother finish and can be used to undercut the bottom of a dovetail housing, or to clear out the corners of fine inlay work.

Sharpening cutters

Sharpen cutters like chisels but rub the cutting edge along an oilstone. Set the stone so cutter's edge clears the bench.

Setting the cutters

Cutters have square sectioned shafts set at 45° to the direction of the cut which are cradled in a "V" groove in the stock. The top -section of the shaft is shaped to locate on the knurled adjusting thread which runs on a threaded rod fixed in the stock.

For through dados, insert the cutter, clamp from the underside, and locate the adjusting nut. Adjust the cutter against the depth gauge and tighten the thumb-screw clamp. Alternatively, mark the depth of the work edge and align the catting edge with the marked line. Mark the depth of the dado on the edge of the work. Remove the hulk of the waste beforehand with a saw and chisel or set the cutter in stages to remove all the waste after making two saw cuts on the waste side.

Adjustable fence This positions the cutter the required distance from straight. concave or convex edges. It is located in grooves machined in the sole of the stock and kicked in place with a slotted screw.

Stopped dados

Fit the cutter facing backward to align the cutting edge with the edge of the stock. You may have to reverse the cutter clamp to prevent the thumb screw hitting the work.

Through dados

Push the tool forward. To prevent breakout of the grain at the back edge, reverse tool and work back the other way.

Curved grooves

When cutting curves work from two directions to prevent tearing the grain.

Miniature Router

SIZE: Width: 3in.

MATERIAL: Metal

ATTACHMENT: 1/4in. cutter

USE: To use as router plane but for fine, delicate work.

The cutter of the miniature router can be set for stopped or through dados. The depth must be set against a marked line on the work and the cutter secured bv a knurled screw.

Granny's Tooth

OTHER NAME: Old woman's tooth

SIZE: Width: 4 to 6in.

MATERIAL: Hardwood

ATTACHMENT: Steel cutter

USE: To work as for router plane

This is a wooden bodied router with the cutter set at a steep angle and held by a wooden wedge. The blade is adjusted by tapping with a hammer as for wooden planes. The front edge of some models is notched back to the mouth for checking the work and to allow the shavings to clear the slot.

Portable Electric Router

OTHER NAME: Power router

SIZE: Light duty: Motor: 1/4 to 1/2hp; Power: 18,000 to 22,000 rpm; Weight: 3-1/2 to 6lb; Heavy duty: Motor: 3/4 to 1/2hp; Power-- 23,000 to 27,000 rpm; Weighi: 8-1/2 to9lb

MATERIAL: Die cast aluminum alloy

ACCESSORIES: Fence guide; template guide; laminate trimming guide

ATTACHMENT: Dovetail jig

USE: To cut grooves, dados, rabbets and mouldings; to trim

The electric router is a versatile power tool which superseded the hand-router and moulding planes. It is used to cut grooves or moudings quickly and cleanly. The motor is fitted with a chuck and is held in a vertical position by a sleeve fitted with two integral handles.

It stands on a flat circular base which slides on the work. A bit or "cutter" is fitted into the chuck and protrudes through the base plate. The bit can be finely adjusted and locked at the required setting. Because the router runs at extremely high speeds it produces a very smooth cut which requires little sanding. While the lighter machines are suitable for the average domestic user, more than one cut may be necessary to produice a successful groove or moulding.

Operating the Router

The router has a tendency to twist when starting so keep a firm grip on the machine when switching on. The motor must reach maximum speed before a cut is made and should never be switched off while it is in contact with the work. The router is fed into the work against the clockwise rotation of the bit so that the cutting edge pull itself into the work making a vibration free, accurate cut.

Move the cutter at a steady rate: too much speed may strain the motor; too little speed may case friction resulting in damaged work or cutters. With a little experience, the sound of the motor will be your best guide.

BITS

Bits are available in shank sizes ranging from 1/4in. to 1/2in. and are made of high speed steel or tungsten carbide.

Carbide bits can either be solid or tipped; a tungsten carbide cutting edge is brazed onto the shank. While the high speed steel bits perform well on most woods, plastics and soft metals and are available in the widest range of shapes, both types of carbide bits are longer lasting. They have a greater resistance to heat and therefore do not blunt as quickly, particularly when cutting more abrasive materials such as laminates, plywood, particle board and so forth.

Cutting edge design
Double fluted bits (left) cut simple grooves quickly and unguided. More elaborate bits (right) have a pilot tip.

Solid carbide bits are the strongest but are the most expensive and are the best suited to heavy duty machlnes.

The cutting edge on a bit may be either single or double fluted, or spiral shaped. Single fluted bits cut faster as there is more clearance for the waste, but they tend to leave a rippled cut. Double fluted bits make two cuts for each revolution and give a much smoother finish. The spiral bit has a slicing action which produces a very smooth cot bet is slower to use.

Most shaped bits have 2 pilot tip which rides along the edges of the work. These bits can have straight or beveled cutting edges. Pilot tips eliminate the need for other guide accessories but the edge of the work should be clean and true or the bit will copy any irregularities.

Fitting and setting bits

Before attempting to fit any bits, disconnect the machine from the power supply. Insert 1/2in. to 3/4in. of the shank into the chuck before tightening.

While the method of fitting bits varies according to the machine. the motor must always be locked so that the chuck can be loosened with a wrench. Some models have a built-in locking device incorporated in the on-off switch, la the off position the switch is pushed upward to lock the motor shaft (1). Other types have a separate push button (2). A third type (3) uses two wrenches. One tits the shaft while the other turns the chuck.

Setting the cut depth

Loosen the base clamp. Move the motor body back up or down as required and lock into place. Most routers have calibrated dials for fine setting.

Making through cuts

Steady the forward half of the base on the surface of the wood and carefully feed the cutter into the work against the clockwise rotation of the bit.

Stopped dados

Lower the tool perpendicularly down into the work allowing the bit to drill into the surface. Make the cut in the normal way and lift the machine clear before switching off.

Guide fence accessory

This can be fitted to the base for cutting grooves parallel to an edge. The guide usually has two rods which plug into the router base and can be locked in place with two thumb screws. Some types have an additional Vernier adjustment for fine setting and a trammel point for cutting curves or circles. For better support, the fence can be extended with a length of wood screwed to it.

Attaching a guide fence

Plug the guide rods into the router base. Adjust the fence along the rods and lock with the two wing nuts.

Using the router

Cutting dados and grooves

Routers can cut dados or grooves to any angle. Clamped lengths of wood can be used as guides if necessary.

Cutting a narrow groove

Use a single length of wood as a guide for the router base.

Cutting a wide groove

Clamp two parallel lengths of tsood across the work, run the muter against each length in turn before using it free-hand to remove the central portion.

Cutting parallel to an edge

Use a guide fence when making cms parallel to an edge. Attach the fence as shown, right, and extend it if necessary with a length of wood.

Mouldings and rabbets

You can cut a whole range of shapes commonly used in furniture construction by using the wide variety of shaped, piloted router bits.

Moulding an outside edge

For table tops or panels, first cut the end grain and then the side edges. This will prevent the grain splitting out. If the mouldings are to be cut across the end grain only, work from either end toward the middle.

Cutting a rabbet

To cut a rabbet on the inside of an assembled frame, fix a right angle block to the guide fence. The block must be centreed on the guide so that both sides of the cut are even.

Cutting circles or disks

Use an adjustable trammel guide for this. Some guide fences come already equipped with these guides. For thicker beads you may have to adjust the cutter between passes.

Using the trammel guide

Anchor the adjustable trammel point into the wood so that the router can be moved around the central point.

Cutting edge mouldings

To cut mouldings or grooves close to the edge of curved work, use the guide fence with the straight edge plate removed.

Template routing

You can accurately duplicate compass curves or free form shapes by running the edge of the router base against \m. thick plywood templates clamped or tacked to the wood. Bear in mind that the work being cut will vary in size from that of the template's by the distance between the bit and the router's edge. Therefore, when cutting large shapes remember to compensate for this difference.

Copying delicate work

 

For finer work you can fit an appropriately sized template guide into the base plate. This is a metal disk with a tubular collar which projects below the router base. The collar rides against the template while the bit passes through the tube to make the cut. Compensate on the template for the distance between the cutting edge and the outside face of the collar.

CUTTING JOINTS

By setting the depth of cut and guide fence in different ways, you can use the router to quickly and accurately produce a wide variety of joints.

Cutting a mortise

Fit a straight bit which has a diameter slightly less than the width of the desired mortise. Make the first cut. Turn the tool around resting the guide fence on the other side of the rail and make a second cut. This insures that the mortise is centreed on the rail. Square off curved ends with a chisel.

Cutting a short tenon

Hold the work vertically between two wood strips. Make sure that the ends of the rails are flush. Set the fence to produce a tenon to fit the cut mortise. Make a pass from each side.

Cutting a long tenon

Set depth of the bit to equal distance between mortise and edge of rail. Cut first shoulder against the guide. Remove waste and repeat on other side of rails.

Tongue and groove To cut a tongue and groove joint in the edge of the work, clamp the board between two wide pieces of wood to provide a flush surface for the base of the router to ride on. Adjust the fence to cut the groove first.

Dovetail joints

This form of joint, normally used in drawer construction, requires a high degree of skill if cut by hand. However, if a dovetail jig and a router fitted with the matching bit are used, both halves of the joint can be cut simultaneously resulting in a perfect fit.

Using the dovetail jig

Clamp one board horizontally and one vertically in the jig.

Cutting the groove

Set the fence to cut the groove down the centre of the work.

To make the tongue, re-set the fence and make two cuts, one on each side of the work, cutting partly into the support pieces. Make sure they are the same depth. The tongue should push into the groove.

While a standard tongue and groove joint can be made using a straight bit, a dovetail shaped bit makes a stronger joint.

Simultaneous dovetailing

The dovetail bit follows the fingers of the guide, cutting into both boards to remove waste. It leaves the pins in the horizontal board and the tails in the vertical board.

Methods of fitting and adjusting the dovetail jig, and therefore positioning the boards, differ with each manufacturer. Check with the maker's instructions before you start.

Clamp the work in a vice. Sandwich it between scrap wood if it is thin or you are cutting the tongue. For the groove, centre the bit on the board. For the tongue, make two cuts of equal depth, leaving the tongue projecting centrally.