Blades are distinguished by two characteristics: the number of teeth per inch, and the width of the blade.

For a medium coarseness, and as a good general purpose blade, 6 teeth per inch is a good size. Having larger teeth (fewer teeth per inch) will give you a more aggressive cut, but this isn't always best.

To see the difference, imagine the difference in cutting down a tree using a wood saw, or doing the same job with a steak knife. The steak knife has very small teeth or no teeth at all, while the wood saw has large teeth. A tree could be cut down with a steak knife, but it would be difficult: the teeth simply aren't aggressive enough.

And a steak can be cut with a wood saw. But even though the wood saw has aggressive teeth, we know it isn't the right blade for the job. Imagine what making this cut would be like: It would likely take only one stroke, but it would be a difficult stroke. The large teeth would dig in and all the force normally exerted over several strokes would be needed all at once. So even though it would be faster, it would be more difficult.

Now think of what is happening to the blade. As the force pushing the saw is increased, the force on each of the teeth is also increased. At some point this force can become too great and damage the blade, either by causing the blade to be dulled or by actually breaking teeth off. This wouldn't happen when cutting a steak, of course, but this can be a problem with harder materials.

In any cutting job, you want each tooth to be doing a small amount of work. This will keep the force on the teeth light and prevent wear on the blade. But having too few teeth will make cutting impossible (like cutting the tree with a steak knife). Choosing the proper blade involves making tradeoffs.

Blades come in a variety of widths, thicknesses, and sizes, so you can match the blade for the job.

• For wood, aluminum, and brass: use the biggest teeth possible to avoid clogging. These materials are soft enough that damaging the blade isn't a danger.
• Use small teeth for tubes. When cutting round materials, the teeth will grab at the side of the piece and try to turn it; smaller teeth makes this less of a problem.
• Use small teeth for sheets. With thin pieces, it's easy to get the piece caught in between the teeth, concentrating all the force on one tooth.
• Rule on material thickness: have 3 teeth in the material being cut.

There's another problem with cutting thin materials: they make a very loud, piercing sound. It's loud enough to be a danger in the shop, both to you and other people working around you. You won't be able to hear the sound your machine is making, which is important because an unusual sound is often the first way you'll know there is a problem with your machine.

The key feature of the bandsaw is its ability to cut curves. This is possible because of the narrow blade, and the narrower the blade, the sharper the turn possible. With a blade about a half-inch wide, it's possible to cut a curve with a radius of about three inches.

				Cutting wood
				Cutting aluminum
				Cutting a curve