You can have a top of the line circular saw but without a good blade it doesn’t amount to much. Having the right blade for the job you are doing is critical to making a clean cut and making the cut safely. Depending on the material you are cutting and the results you are looking for you have to choose a blade for your circular saw accordingly.
Generally the blade will be a standard 7-1/4″ in diameter. You can get general purpose blades for under $10 but to get a high quality blade you can expect to pay $50, $75 or more.
When choosing a blade I prefer to have a thin-kerf blade since it is easier to make a cut (kerf refers to the width of the cutting teeth). I also inspect the blade to make sure there are no chips in the carbide teeth. Running your finger nail along the edge of the blade will reveal any pits that you cannot see.
The blade and teeth should have no rust and be smooth and shiny. A dirty blade requires more force to make a cut which will result in a rough cut or cause an injury. Any dirty blades should be cleaned by using an industrial cleaner. This will dissolve any pitch or gummy substances left from cutting wood.
Different circular saw blades and their uses
Masonry Blade
A masonry blade is smooth with no teeth. This is because it grinds material away rather then cuts it. When using a masonry blade you should always wear a dust mask to prevent inhaling and hazardous substances. Masonry blades are ideal for scoring concrete pavers or cutting bricks.
Plywood Blade
Ideal for cutting cabinet grade plywood or plywood with a thin veneer, plywood blades nibble away the wood rather then chew it up like a general purpose blade. A plywood blade has a lot more teeth then other types of circular saw blades, often over 70 teeth. This makes for a very clean cut with no chip-out.
Chisel Tooth Blades
These types of blades are what usually come with a low to mid range circular saw. They often have only steel teeth which cut very well when sharp but are easily dulled. They are seldom used by professional since they do not maintain their cutting edge.
Trim Blades
Primarily for finishing cuts, a trim blade has 40 to 60 teeth, each with a premium carbide tip. A trim blade cuts slower then a general purpose blade but leaves a smooth sharp edge. They are ideal for cross cutting dimensional lumber and cutting plywood.
Decking Blades
Used for trimming off decking and other premium dimensional stock a decking blade has a thin kerf with a raised shoulder. This allows it to easily cut through even the hardest pressure treated lumber or knots in cedar or teak. Most decking blades also have a radial slot which reduces warping while cutting and prevents deep saw marks.
Remodeling Blades
These blades are primarily used for demolition work. They have far less teeth then a finishing or decking blade, often as few as 10 or 12. The teeth are also very robust with square shoulders and a wide kerf. It is ideal for rough cutting and cuts where nails and other debris could be present. Since this type of blade is so aggressive there is a lot of chip out. Avoid using a remodeling blade on finishing type cuts.
General Purpose Blade
This blade is used for most general cutting. Almost every circular saw will have a general purpose blade included with it. They are great for ripping or cross-cutting but do have some tear-out so should be avoided with finishing cuts. General purpose blades will usually have 20 teeth with carbide tips and cut smoothly when sharp.
Cutting with a circular saw is one of the most common ways to rip and cross-cut lumber and plywood. However there is always a risk of kick-back. Set the depth of the blade so it is just slightly deeper then the thickness of your stock. This will reduce the risk of kick-back and other injuries.
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