The gullet is the rounded space, cut into the blade plate, between the teeth. This space is designed to carry away waste, such as sawdust and chips; prevent the blade from clogging. The size of gullets on the saw blade is closely related to the feed-rate factor. Crosscut saw blades have more teeth and thus smaller gullets, while the heavy-duty and rip saw blades have larger spaces between each tooth to remove the sawdust quickly.
Against Heat
This gullet is necessary to help prevent blade overheating and burning of the material being cut. Without a large enough gullet, sawdust becomes trapped, sticking to the blade and increasing friction, thereby producing excess heat. Since sawdust burns much easier than solid wood, it is actually possible (although uncommon) to start a fire this way. With enough overheating, the blade can begin to warp, increasing the saw thickness and ultimately destroying the blade. For this reason, it is not recommended to try and rip with crosscut blades. The smaller, more frequent teeth on the crosscut blade are accompanied by smaller gullets, which don’t have enough capacity to carry the larger amount of chips and sawdust away. Crosscut blades cut slower and have enough time to draw out the waste material so the large gullets are just not needed. Even if you could force the wood through the saw blade, it would jamb, because of the buildup of sawdust and chips.
Sawdust
Combination circular saw blades are used for both ripping and crosscuts. When used for ripping, saw blades tend to accumulate too much sawdust in the saw kerf. Some combination circular saw blades solve this problem of chip buildup by skipping teeth and adding an extra deep gullet after every five teeth or so. A deep gullet between the groups of sawtooth profiles allows a place for the excess sawdust to be removed from the saw kerf, thereby eliminating the overheating problem.
Softwoods tend to create larger and looser packed chips than hardwoods. So, this problem of sawdust accumulation in the gullet can be worse with softwoods. If you are cutting damp wood, the problem is only increased, as the dampness in the wood will help it to clump together, instead of falling clear of the gullet. The temperature grows as the blade gets clogged more and more, carpenter can only notice it when circular saw begins to strain or blade plate starts to bend. The reason why the opposite case is an obvious mistake and happens less likely: when ripping blade is mistakenly used for crosscuts, the fact that rip saw blade makes untidy cut with a lot of waste and large splinters of wood prevents woodcutter from using it.
Non-ferrous Metals
Aluminum and brass, both of which can be cut with a carbide tipped circular saw blade, have a tendency to stick to the blade. More than anything, they will stick to the face of the teeth. In this process, these materials can easily clog up the gullet, preventing the blade from sticking. If you are cutting either of these materials, stop frequently to inspect the blade for material sticking to it.
Blades with Large Gullets
Although saw blades are not rated by the size of their gullets, this is something that is easily visible when examining the blade. The blade designers take the intended use of the saw blade into consideration, ensuring that they provide a large enough gullet for the intended purpose. However, when the blade is used purposes other than the intent, especially when a crosscut blade is used for ripping, the gullet may not be adequate.