See Also

Grooves aren't always straight. Page through the chapter "Routing Curves and Circles" for ideas on routing curved grooves using trammels, templates, and other devices.

Though this chapter hits f<x:used on fence-guided cuts, you can rout dadoes and grooves guided by a template. You reference the template with either a template guide bushing or the shank-mounted bearing of a pattern bit. See the chapter "Template-Guided Work" for more information on making and using templates.

STAGGER-TOOTH STRAIGHT BIT

SHEAR-CUT STRAIGHT BIT

CARBIDE TIPPED SPIRAL BIT

SOLID-CARBIDE SPIRAL BIT

SINGLE-FLUTE STRAIGHT BIT

STAGGER-TOOTH STRAIGHT BIT

SHEAR-CUT STRAIGHT BIT

SOLID-CARBIDE SPIRAL BIT

SINGLE-FLUTE STRAIGHT BIT

diameter bits with flute lengths of Vi. 1, 1'/«, Wi, 2, and 2Vi inches.

So how do you choose which to buy (or use)?

Take the shortest length for work to be done. For dadoes, choose the one with the V^-inch-long flutes. That's plenty long for cuts that will seldom exceed a Vi-inch depth.

If you have a plunge router, make sure you arc getting bits that have plunge-cutting ends. Most do these days, but check before you buy.

Finally, remember that bits at the extremes of the size range are generally not guaranteed by their manufacturers, simply because they take the tooling to the outer limits.

Shear-cut straight bits are variants of the double-flute straights. A bit of this design is called shear-cut because the cutting edges are at a slight angle (usually about 3 degrees) to the bit's axis. In a broad sense, the shear-cut bit shaves the work, rather than chopping it. A shear-cut bit is often recommended when the finish from a standard bit would be inadequate or when the bit will be used in a relatively low-horsepower router.

Single-flute straight biLs should be used where the cutting speed is more important ihan the cut finish. These bits cut once per revolution, allowing faster feed rates but yield what bits to buy when expanding your inventory.

Double-flute straight bits arc

THE basic router biLs. Each bit has two vertical cutting edges, and thus it makes two cuts per revolution. Use a double-flute straight when the finish is primary and the feed rate is secondary'.

An enormous variety of sizes is available. Some manufacturers list 50 or more different double-flute straight bits. Cutting diameters from lAt inch to 2 inches, with flute lengths from Va inch to 2Vi inchcs. Even metric sizes are available (from Hyrom; see "Sources" on page 337). The typical catalog may list '/¡-inch-

CARBIDE TIPPED SPIRAL BIT

ing rougher cuts. Because there's only a single flute, there's extra chip clearance. The tip is generally designed for fast plunge cutting.

Available cutting diameters range from '"ihinch to Ysinch; flute lengths range from ¥> inch to 1 Vi inches. Byrom markets a 14-millimctcr-diameter single-flute bit.

The single flute is easy to sharpen by hand, by the way.

Stagger-tooth straight bits are so called because they have two cutting edges spaced 180 degrees apart. each half the length of its flute. One extends from the tip to the middle of the flute, the other from the middle to the end. The benefit of the design? It combines the cutting speed and chip clearance of a single-flute bit with the finish of a double-flute bit. Stagger-tooth bits are intended for cutting dense or abrasive man-made materials and panel goods.

Available sizes range from Y*-inch to %-inch cutting diameters with Winch to 1 '/2-inch flute lengths.

Paso Roblcs makes its stagger-tooth straights with downshear and upshcar on alternate edges. This way, the shear angles on a through cut are toward the center of the stock, fills is great for veneered stock (like plywood). An upshcar tends to lift the veneer at the edge of the cut, leaving a raggedy, fuzzy edge. A down-shear pushes the veneer down, slicing it cleanly. The Paso Robles stagger-tooth shears down on both surfaces at the same time. Dynamite!

Spiral bits are shaped very much like twist-drill bits. Spiral-flute straights combine a shearing action in cutting with an augering action in chip clearance. The shearing action yields an especially clean, accurate cut, while the augering action clears the chips up (or down) and out of the cut. A trade-off is a reduced cutting rate.

Spirals arc available in upshcar and downshear designs. In a dado-cutting operation, the upshcar spiral will lift the chips out of the cut. But it will also lift the wood fibers along the edges of the cut—it's paring ftotn die bottom of the cut toward the surface, after all. The downshear spiral is a response to the latter problem. Its cutting action is from the surface down, so it leaves a smooth edge at the surface. But it is also augering the chips toward the bottom of the cut.

There is a subsidiary dynamic stemming from the shear direction. The upshcar action pulls the work against the router, while the down-

shear action pushes the work away from the router.

To get the twist, manufacturers make the entire bit from either carbide or high-speed steel (HSS). (Paso Robles spirals are carbide-tipped, but they don't have the degree of twist that other brands do. They seem more like shear-cut straights than spirals.) The HSS spiral is sharper to begin with, but it dulls relatively quickly. The carbide spiral holds its edge a long time, but it is brittle. It is also pricey: A carbide spiral generally costs about two-and-a-half times what a comparable HSS spiral does.

Spirals arc available in cutting diameters of '/a inch through ¥\ inch, with (lute lengths varying from Y* inch to l Y¡ inches.

Dado bits, curiously enough, are listed by only two sources, Paso Roblcs and Woodhavcn. (And 1 sus pect that Woodhavcn gets its dado bits from Paso Robles.) Chunky straights arc what they arc, being an inch or more shorter than comparable straights. Their advantage over common straight bits is reduced vibration—a result of the shon. thick body—coupled with downshear cutting. The cutting edges are shon. too—Ye inch. The cutting diameters range from Yi inch to 'Mftinch.

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Woodworking Tools and Installation Tips

Woodworking Tools and Installation Tips

There are a lot of things that either needs to be repaired, or put together when youre a homeowner. If youre a new homeowner, and have just gotten out of apartment style living, you might want to take this list with you to the hardware store. From remolding jobs to putting together furniture you can use these 5 power tools to get your stuff together. Dont forget too that youll need a few extra tools for other jobs around the house.

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