68 - Our All-New Router Jig, страница 11

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are made out of carbon steel. And for cutting wood, these work just fine. But if you are going to be cutting metal, you might want to take a look at bi-metal blades. On a bimetal blade, the teeth are cut into a strip of high-speed steel welded onto a blade body of softer, carbon steel (which is why they're called "bi-metal" blades). The high-speed steel teeth will hold an edge much longer than carbon steel teeth. And the softer carbon steel body of the blade will allow it to flex during use without breaking.

In addition to cutting metal, bimetal blades are also handy for cutting wood that may have an occasional nail embedded in it. You can usually identify bi-metal blades by the fact that they are painted white.

Blade Style - There's one other thing to consider when selecting jig saw blades. It may seem obvious, but make sure to choose a blade that is

Specialty Blades

compatible with your saw. Some jig saws accept T-style blades, while others accept universal blades (see the photo in the margin at right). A few saws work with either one.

Sorting It All Out - Now that you're armed with all this information on jig saw blades, how do you put it to use? Well, I like to keep an assortment of at least two or three different types of blades so that I can select a blade that is best-suited to the task at hand.

For general woodcutting, I typically use an 8 tpi blade. This blade seems to be a good compromise between speed and quality of cut.

For construction-type tasks, like roughing out an opening for a pipe or ductwork, I switch to a blade with 6 tpi. This is the blade to use when you want to get the job done quickly and you aren't terribly concerned about the looks of the finished product. For making scroll

cuts on a furniture project, I want as smooth a cut as I can possibly get Since finish is more important than speed, I'll use a finer blade — one with 10 or 12 tpi.

Keep in mind that there is a lot of overlap in jig saw blades. In other words, you don't have to change blades every time you make a different kind of a cut A medium or fine-toothed blade might not cut through a 2x4 as quickly as a coarse-tooth blade, but it will still get the job done in a pinch.

I also like to keep a couple of bimetal, wavy-set blades on hand for cutting metal or plastic. I don't use these a whole lot, but they sure come in handy when I need them.

One other thing. Since you may occasionally find yourself facing a specialized cutting job, you might want to take a look at some of the specialty jig saw blades shown in the box below. &

Universal

A Some jig saws use T-style blades (top) while others use universal blades (bottom). A few saws will accept either style of blade.

In addition to standard blades, there are a number of different "specialty" blades available for specific applications or for cutting materials other than wood or metal.

Downcut Blade - For cutting laminated or veneered surfaces, you can use a downcut blade. The teeth on this type of blade point down instead of up, so it cuts on the downstroke. This limits the chipping and splintering to the underside of the cut.

Flush Cut Blade - With a standard jig saw blade, it can be difficult to cut all the way up to an obstruction (like a wall). A flush cut blade has an aggressive tooth pattern and is wider, so it has a greater reach than standard blades. It comes in handy when cutting an opening in a countertop that is installed against a wall.

Knife Edge Blade - For cutting leather, foam rubber or vinyl, you may want to try a knife edge blade.

These blades don't have any teeth at all. Instead, the cutting edge is shaped like a knife blade. So the blade slices rather than saws its way through the workpiece.

Carbide Grit Blade - A jig saw probably isn't the first tool you'd

think of for cutting ceramic tile. But for short cuts, it works just fine — if you have a carbide grit blade. The edge of this blade is embedded with abrasive grains of carbide. So it will cut through ceramic, cast iron, and other tough materials.

Downcut ►

blades cut on the downstroke to reduce topside chipping.

Knife Edge ►

blades can be used for cutting leather, cork, rubber, or vinyl.

Flush Cut*

blades are wider to allow you to cut in closer to an obstruction.

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