Table saws need their blades replaced occasionally. The key is to choose a replacement saw blade that works well with both the type and size of the saw and the type and size of the material to be cut.
Match the Saw Type
With some exceptions, a blade must match the specific type of saw. Otherwise, the saw could damage itself, blow a fuse, or even kick up the material being cut. Using a circular saw blade instead of a mitre saw blade for a mitre saw is ineffective and dangerous.
Each saw works with a specific size blade. The wrong size might not mount properly or cut deeply enough, and the size of a blade determines the speed of its cutting edge for any given RPM. A change in blade size changes cutting speed and thereby affects the performance of the saw. Some people do buy a variety of blade sizes to get specific performance characteristics, but varying the size is an advanced skill.
Wood cutting blades are the most popular, but specialty blades can cut laminate, tiles, and more. A specialty blade, in turn, cannot cut wood well. With the exception of some metal cutting blades, specialty blades still have to follow the size and type requirements of the machine.
Number of Saw Teeth
Blades with many teeth make smooth, fine cuts, while coarser tooth patterns are better for cutting thick material quickly. When cutting plastics, the wrong tooth count could actually melt or chip the plastic, depending on the type of plastic. Each saw type has its own range of tooth counts, so high and low are relative. Hobbyists who do not want to buy a whole collection of blades can choose an intermediate tooth count that can do a little of everything.
Tooth design is a complex issue and manufacturers sometimes disagree as to what configuration is best for what type of job. A beginner can just go with a manufacturer's recommendation for the saw and material type. Buyers ready to explore tooth design more deliberately should consider rake angle. A positive angle means each tooth leans forward and vice versa. Not leaning at all is a neutral angle. Other important variables include the bevel, or the angle of the top of the tooth, and whether all teeth are alike or alternate in some way. Put these variables together, and it results in dozens of different tooth designs. More established users can go ahead and see what works best for them.