Dear James: Last time I used my circular saw, the blade was dull, and the cuts were rough. When I get new ones, what type of blade works best and how many teeth should there be? -- Megan R.
Dear Megan: If you have already shopped for a circular saw blade, you probably noticed a huge selection with prices ranging from $30 to more than $100 depending on the type and quality of blade. It is easy to change a saw blade, so it is wise to get several different blades depending upon the various projects you plan to tackle.
The number of teeth typically has the most impact on how well a blade works for cutting various materials and the speed of cutting. There also are different tooth designs and hardnesses, which affect the cutting and the life of the saw blade. Some materials, such as laminate flooring, can dull a blade faster than wood.
A general rule of thumb is a blade with fewer teeth will cut wood faster than one with many teeth, but the quality of the cut will be rougher. When just rough-cutting wall studs or other structural lumber, a low-tooth-count blade is ideal. Your primary concern when making these saw cuts is just getting the piece to the proper length and making it square, which is a function of the saw quality, not the blade.
A saw blade with more teeth cuts slower, but the quality of the cut edge will be much smoother and cleaner. Even if you have plenty of time, you may not want to use a high-tooth-count blade. The slower cutting results in more heat buildup, so using this type of blade when it is not needed can result in burning the wood edges. When making fine-quality furniture and cabinetry, this can ruin the piece of wood.
The least number of teeth you will find on a circular saw blade is about 14. A circular saw blade is only 7 1/4 inches in diameter. Fourteen teeth are ideal for the rough cuts on 2-by-4-inch framing lumber, and they cut very fast. If you attempt to use this type of saw blade to cut thin material, it will literally destroy the wood. It would also create an unacceptable cut on plywood.
A 24-tooth blade is a good compromise for many cutting jobs, and it is the most common blade supplied with new circular saws. It is, however, still considered a fairly low number of saw teeth. You will find this blade produces a reasonably smooth rip cut (along with the grain of the wood), but the crosscut (across the grain) will be quite rough.
If you are planning to do any cutting of plywood or plastics for your projects, select a blade with 40 or more teeth to minimize the amount of tear-out on the wood surface. This blade also produces a fairly nice crosscut on solid lumber. For cutting high-quality veneered plywood and some plastics, use a blade with 60 or 80 teeth.
When fitting joints together, you will use a miter or cutoff saw. This is typically a larger-diameter blade with more teeth. Most of the cutting done on this type of saw is crosscutting, so a blade with at least 80 teeth is advisable for clean edges.
