Getting the right saw blade for your project can be the difference between a great result and an okay result. Understanding what type of sawblade you're working with can help you plan for any side effects the blade might introduce.
Blades are specified in a number of different ways and usually the manufacturer's packaging will state what the blade is floor.
Rip cut - goes along with the grain of the wood. This type of cut is less prone to tear out than a cross cut. These blades typically have fewer teeth.
Cross cut - goes across the grain of the wood. This type of cut is more prone to tear out than a rip cut. These blades typically have more teeth.
TPI is a description of the coarseness of the blade and is specified by the number of teeth per inch along the blade.
Generally, a blade with a lower TPI will produce a rougher cut than a blade with a higher TPI, no matter the material or the direction of the grain.
The shape of each tooth can be described from the side (looking at the flat side of the blade) and from the profile (looking along the cutting edge).
Flat Top blades have a flat top that is square to the saw plate and are good for rip cutting soft and hard woods. They cut fast and are very durable but produce a rough cut.
Alternate Top Bevel blades have teeth that are angled across the top edge with every other tooth is angled in the opposite direction from the previous tooth. The shape of the teeth gives a clean tear through the material at the cost of dulling faster.
Combination Tooth Combination or general-purpose blades have a mixture of ATB and FT teeth and are designed for general-purpose cutting. They can be used for both ripping and crosscutting. These blades have a variation of ATB teeth mixed with an FT raker tooth and a deep gullet to help with ripping tasks.
Triple Chip Grind blades consist of alternating teeth. Each tooth alternates between angled and squared. Each ATB (angled or chamfered) tooth chisels the cut while the raker tooth follows behind to clean the roughness.
For steel blades, the tooth profile is determined by how it is cut and ground, and how far each tooth is bent off axis along the direction of the cut. These teeth are flat or alternate top beveled as created by the bend, which also creates the kerf.
The angle at which the tooth projects from the saw blade, along the axis of the cut.
Higher positive hook angles will yield more aggressive cuts with a faster feed rate. Low or negative hook angles will slow the feed rate and reduce the blade's tendency to climb the material.
The gullet is the space between the teeth that collects the cut out chips. It determines how much material can be removed by each tooth and is a determining factor in how fast the cut can be made.
Kerf describes the width of the slot created by the blade. This is specified from the manufacturer and for table saw and miter saw blades it is typically 1/8th inch.