For a long time, wood was cut with an axe. As humans evolved, so did their tools. Now smartphones do the wood cutting—if you call somebody with an axe. However, before smartphones, the world experienced the Industrial Revolution and large water- and steam-driven circular blades, with sharpened teeth on the circumference, became the heart of every saw mill. Today’s electric circular saws are just smaller, electric versions of those lumber mill saws. If you cannot call someone to cut something for you and you need something lighter and more portable than your typical saw, then they are the ideal choice. They can go where the work is, instead of the other way around.
When outfitted with an appropriate blade, a circular saw can cut many different materials, including but not limited to:
- Hardwood and softwood lumber
- Plywood and manufactured panels (like particle board, flake board and medium density fiberboard)
- Plastic laminate and laminate flooring
- Light-gauge steel
- Vinyl and aluminum siding
- Wood siding
- Natural stone
- Concrete blocks and pavers
- Ceramic tiles, quarry tiles and terra cotta roof tiles
- PVC and ABS plumbing pipes
The only serious drawback to this tool is that it can be dangerous. All models come with a retractable blade guard above the saw base that protects you from material thrown from the top and sides of the tool. However, when working, as much as 12 square inches of blade (turning at thousands of RPMs) can be exposed under the base. Be extremely careful when using a circular saw and wear proper eye, ear, and lung protection regardless of the blade that is installed.
Choose a Blade
Most circular saws come standard with a 7¼-inch-diameter blade and a motor that draws 8 to 15 amps of power. Many tools have automatic brakes that stop the blade when the trigger switch is released and dust collection ports that direct dust to an onboard bag or vacuum hose. The most important saw feature is the blade that is installed. The same tool may have the power to cut plywood or concrete, but it can only do each job if it has the right blade. Here is a quick guide to different blades for cutting common materials.
Wood blades come in many different styles, but the basic difference between them is their quality of cut, which is a function of the number of teeth the blade has. The 44-tooth blade (left) makes a smooth cut and is used for trim carpentry and cabinet making. The coarse 24-tooth blade (right) cuts quicker and is used for rough carpentry work.
Wood Cutting Blades
There are many different wood cutting blades available, but most fall into two categories: construction blades and plywood blades. Construction blades with fine-cutting blades (more teeth on the circumference means a finer cut) typically have forty or more teeth. Blades listed between twenty and forty teeth are designed for basic carpentry work where a smooth cut is not important.
The teeth on construction blades have deep gullets to carry away the wood chips and sawdust. In most cases, the quality of cut is not very important when doing rough work, but when a cleaner cut is required, the board should be cut from the back side. This is because the blades cut in a counterclockwise direction. When a tooth enters the material, the cut is clean. When it exits, it can splinter the surface. The idea is to keep the cleanest cuts visible. Most hardware stores and home centers will have two types of blades: high-speed steel and carbide tipped. The first is cheaper while the second lasts much longer.
Some blades, like this plywood cutting design, are marketed for multiple materials, but the high number of very small teeth defines the blade as a plywood panel cutter. It yields smooth and straight cuts in materials no more than ¾ inch thick.
Plywood blades, on the other hand, are made of high-speed steel and have many small teeth, often as many as 160 per blade. Because of these small teeth, the cut on both sides of the material is cleaner. This generates less dust, and the blade tends to cut straighter because there is always much more blade in contact with the cut. Plywood blades work well for cutting laminate too.
Masonry Cutting Blades
A masonry cutting blade, like this high-performance model, is designed for cutting hard materials like concrete and natural stone. Other models look the same but are used on softer materials like concrete blocks, bricks, and ceramic tile.
It may be a little counter intuitive to think that a circular saw, which is primarily used for cutting wood, can also be used for cutting concrete blocks and natural stone. Try to remember though, it is not the saw that makes the cut, but the blade. Masonry blades are toothless and are made of fiberglass-reinforced silicone carbide abrasive. This is the same material that is commonly used in sandpaper.
Two blade types are available. The first is a coarse version for softer materials like concrete block, brick, and limestone. The other is made for harder materials like concrete, marble, granite, and all types of glazed ceramic tile. Keep in mind that these cuts are extremely loud and dusty, so be sure to wear ear protection and work clothes. While the blades can cut through these materials, most people start with a scoring cut that is about ¼-inch deep. Then they tap a cold chisel along the cut, which will usually split the material along the scored line.
Metal Cutting Blades
Metal cutting abrasive blades are toothless and usually have heat expansion slots cut into the blade to help dissipate the heat generated when cutting metal.
You can cut copper tubing, aluminum flashing, aluminum siding, and most other types of ferrous and non-ferrous metals (like brass, bronze, and light-gauge sheet steel) with a metal cutting blade. These designs are toothless abrasive blades (sometimes with heat slots) like the ones mentioned above for cutting masonry. But these two types of blades are not interchangeable. Metal-cutting blades are made of different materials to reduce the chance of shattering when cutting very hard objects. Make metal cuts slowly and be sure to wear work gloves.
Plastic Pipe Cutting Blades
Blades with a high number of teeth, like this 60-tooth model, are designed for cutting all types of plastic materials and some soft, non-ferrous metals.
A wood cutting blade with forty or more teeth works very well for cutting plastic pipe. The only thing you need to be cautious about is the speed of cut. Just remember: the slower, the better. If you force the blade into the pipe too quickly, it can get stuck in the pipe, kick back toward your body, or chip along the cut line. Feeding the blade into the pipe slowly should prevent all these problems.
Acrylic Sheet Blades
Some plywood cutting blades (or other high-tooth-count blades) are recommended for cutting acrylic (Plexiglas) panels. But the results are often unsatisfactory. The better approach is to use a jig saw with a fine blade, or a table saw with an 80-tooth (or finer) blade. Straight cuts with a circular saw and fine blade can work, especially if the panel and a straight edge guide board (for the base of the saw) are clamped in place. Make the cut quickly using a smooth pushing motion.