A tablesaw blade is not a complicated piece of equipment, however like every other tool in the workshop, it has been designed to fit a specific purpose. That is why there are so many different choices of saw blades on the market.

As simple as a blade is, they can vary in a number of ways. The main characteristics are:

Number of Teeth
Gullet Spacing
Tooth Configuration
Hook Angle
Kerf Width (and Blade Thickness)
Expansion Slots
Teeth Tip Material
Arbor Size

In order to understand why we want a specific saw blade, we need to know the different types of cutting operations that woodworkers perform. There are blades designed for ripping lumber, crosscutting lumber, cutting veneered plywood and panels, cutting laminates and plastics, cutting melamine, and cutting metals. There are also general purpose and combination blades, which are designed to work well in two or more types of cut.

Number of Teeth: The more teeth the blade has, the smoother the cut will be. The less teeth, more material will be removed more quickly, but the rougher the cut will be. So, in general, a ripping operation where the blade moves along the grain has fewer teeth that remove more material. In a cross cutting operation, where the blade is moving across the grain, there are more teeth that remove less material, as the blade must do harder work.

Gullet Space: The gullet is the space in front of each tooth to allow for wood chip removal. In a ripping operation, the feed rate is faster than in crosscutting and the chip size is larger, so the gullet needs to be deep enough to make room for the large amount of material it has to remove. In a crosscutting blade, the chips are smaller and fewer per tooth, so the gullet is consequently smaller. Sometimes the gullets on crosscutting blades are made smaller on purpose in order to slow down the feed rate.

Tooth Configuration: There are 5 different ways the teeth on a saw blade can be positioned.

	Flat Top (FT) Flat top teeth are used on blades made for ripping hard and soft woods. Since wood is much less likely to chip and splinter when it is being cut in the direction of the grain, the focus of a rip blade is to quickly and efficiently remove material. The flat top tooth is the most efficient design for cutting and raking material out of the cut.
	Alternate Top Bevel (ATB) "Alternate top bevel" means that the saw blade teeth alternate between a right and left hand bevel. This tooth configuration gives a smoother cut when crosscutting natural woods and veneered plywood. The alternating beveled teeth form a knife-like edge on either side of the blade and make a cleaner cut than flat top teeth.
	Combination Tooth (Comb.) The combination (4&1) configuration is used for "combination" blades -- blades designed to do both crosscutting and ripping. The teeth are arranged in groups of five - four ATB teeth and one FT -- with a large gullet in between the groups.
	Triple Chip Grind (TCG) The TCG configuration excels at cutting hard materials like laminates, MDF, and plastics. Teeth alternate between a flat raking tooth and a higher "trapeze" tooth. The TCG configuration is also used for non-ferrous metal cutting blades.
	High Alternate Top Bevel (HiATB) The HiATB configuration is used for extra-fine crosscutting and to cut materials surfaced with melamine, which is prone to chipping. The high bevel angle increases the knife-like action at the edge of the blade.

Tooth Hook Angle:

As you can see, the angles of the teeth are different, the one on the left having less of an angle, and the blade on the right has a high positive angle.

A blade with high positive hook angle (20 degrees or more) will have a very aggressive cut and a fast feed rate. A low or negative hook angle will have a slower feed rate and will also inhibit the blade's tendency to 'climb' the material being cut. You want a high hook angle when ripping boards on a table saw. On machines where there is a tendency to have 'climb', such as radial arm saws and sliding compound miter saws, you want a blade with a very low or negative hook angle for safety.

Kerf Width: The kerf refers to the thickness of the cut. The teeth cut a path that is just a bit wider than the actual thickness of the blade itself. This is to prevent the blade from binding when cutting. A typical kerf width is 1/8". This width allows for a blade that is thick enough to absorb vibration.

There are blades with thinner kerfs, used to reduce the amount of waste that is removed from each cut. These thin kerf blades have laser cut lines throughout the blade to reduce the vibration. Simialrly, in the pictures above, you can see an example of an expansion slot. These are cuts in the blade body to prevent warping problems that can happen as the blade heats up from cutting friction.

Teeth Tip Material: The carbide tipped tooth is found in nearly all blades now adays, though there are some times when it is best to use a blade that doesn’t have carbide tips. When cutting wood that might have metal in it somewhere, whether it be nails, bullets or other items, a relatively cheap non-carbide blade is a much better possible sacrifice than is your top-of-the-line rip blade.

The general principle of the carbide tip is that it is harder and holds its edge and sharpness better than steel for example. But the downside of it being harder, is that it is more brittle and will chip more easily when it hits a hard object such as metal (whether it in the wood, or when you are storing the blade).

When selecting carbide tipped saw blades, look carefully at the size of the tips. The tips must have enough material to allow multiple resharpenings before they are used up.

Look for C3 or C4 carbide in the tips. These are super fine micro grain carbide that takes, as well as holds, a very sharp edge. C4 is used only in premium blades.

Arbor Size: Lastly, as this does not impact the quality of the blade, the hole at the center of the blade needs to fit properly on to your saw. Typically, it is a 5/8".

As with all woodworking equipment and tools, buy the best quality saw blade that you can. A lower quality blade may save you some money up front, but the time you spend having to repass a cut, or sanding off a burn mark will come back to haunt you in the future.