Jig Saws

With its tiny blade extending straight downward, the jig saw may look like the weakest member of the saw family. But its ability to cut graceful curves, as well as its portability, make it one of the most sought-after power tools.

Circular saws cut far faster than jig saws but only in a straight line. And while large band saws can turn out graceful curves and loops, they can't exactly be dropped into a toolbox. The jig saw's combination of cutting agility and lightweight size make it ideal for cutting out sink holes in countertops, cutting openings for electrical outlets, making decorative scrolls for cabinets or shelf brackets, and scribing trim to make it conform to an uneven surface such as brick or stone.

And, yes, it can even cut out the puzzles that bear its name.

No matter what the brand, jig saws operate in the same way: a stubby blade that extends downward from the motor housing moves up and down at a rate of up to 3,000 strokes per minute. They're not the fastest saws in the shop, but they're precise--and the ability to maneuver them carefully is crucial.

Handle Styles: Something to Hold Because of its precise nature, more attention is paid to the type of handle a jig saw is equipped with than just about anything else.

Two types exist:

• Most American-made models come with a handle that forms a loop at the top of the housing. It's comfortable to hold.
• Many European models come equipped not with a separate handle, but a grip that surrounds the motor housing--similar to the type found on orbital sanders. This allows a closer connection with the tool that some people prefer because it gives a greater sense of control.

The Professional Advantage: Beyond the handle varieties, jig saws come in two basic categories that can be divided by price. Homeowner models generally cost below $100, and offer the basics--a blade that moves up and down, usually at a fixed speed.

More expensive, professional-grade models have added features that can make the jig saw easier to use over long periods of time:

• Variable speed controls to adjust the rate at which the blade moves.
• A quick-changing device allowing the blades to snap into place rather than being screwed or bolted.

The action of the blade can also be upgraded:

• More expensive models have something called orbital action, which swings the blade slightly forward on the upstroke and helps the blade cut more efficiently. This makes cutting curves easier, since the blade won't tend to bind.

Blades: The Tooth of the Matter Jig saws are among the most versatile cutting tools, a trait they owe to the assortment of blades with which they can be fitted. The shank, or top end of the blade that attaches to the saw, has to be compatible with the saw; some screw into place, others are held by a hook.

Although the overall shapes can vary from 3 to 6 inches long, the biggest difference lies in the number of cutting teeth per inch.

• The most common all-purpose blade has six teeth per inch, and balances speed with smooth cutting action.
• For cutting curves, a scroll-cut blade with between 10 and 20 teeth per inch is the ideal.
• The more teeth, the more intricate the detail that can be cut, but the more delicate the blade.
• For cutting metal, choose high-speed steep blades with 14 teeth per inch, which can also be used for making smooth cuts in wood.

Jig saws can also be fitted with carbide-grit blades that grind, rather than saw, through thin materials such as ceramic tiles. Make sure that whatever blade you use is sharp. Check by inspecting the teeth and making sure the edges look crisp. If they're not, it's time for a new blade.

Beyond the Basics: Other features to look for include dust ports, so the tool can be attached to a shop vacuum to suck up the sawdust, and a changeable steel shoe, which can be swapped for plastic when cutting easily scratched materials such as laminate for countertops.

When a jig saw cuts, the teeth point upward to keep the tool pulled down tightly toward the wood. Unfortunately, this also sends the sawdust upward, which can obscure the cutting line. Most jig saws have a built-in blower to keep the line clear. And to reduce splintering, some come with a plastic insert that surrounds the blade where it enters the shoe. This presses down the wood fibers adjacent to the cut to help keep them intact.

Curtis Rist, a writer for This Old House magazine, parks his power tool collection in New York's Hudson River Valley.