How To Choose a Circular Saw
Probably the most basic and versatile handheld power tool, in the hands of an experienced user, the circular saw can substitute for many other tools. While it takes some practice for most beginners to get comfortable with a circular saw, it quickly becomes a standby tool to handle a lot of cutting tasks very quickly. This should be the first of the power woodworking tools every beginning woodworker should consider.
It can be used for cutting wood, masonry, metal, and even ceramic tile.
Its strength lies in its portability. A tablesaw is limited by the size of its table, a circular saw can be used on any piece of lumber, no matter the size. This is especially handy when dealing with full sheets of plywood, since full sheets are often very heavy and cumbersome to pass through a tablesaw, especially without the aid of an assistant.
Your choice of a circular saw should be based on what you plan on cutting, and how much you intend on using it. Sizes (of the blade) range from 3″ to 16″, but 5 3/8″ to 7 1/4″ are the most common. The models that support a larger blade offer the capability to cut through thicker stock, while the smaller models offer the portability and the ability to manoever better. Choose the size that suits your needs, but for a general-duty circular saw, I would recommend the 7 1/4″ corded model with in-line motor.
Two basic configurations are available today. There is the in-line circular saw and the worm drive circular saw.
The in-line saw has the motor positioned to the side of the blade, and the blade spins at exactly the speed of the motor. This design is well suited for most applications, and is the recommended model.
The worm drive circular saw has the motor parallel to the saw blade, with the shaft of the motor pointing forward. The shaft turns gears to increase the torque available to the blade, making this design ideally suited for heavy-duty applications, such as for masonry.
Like most power tools, there is standard corded model and there is the battery-powered cordless circular saw.
Corded models offer an unlimited amount of cutting-time, and offers the power required when cutting through masonry or metal. The most common size available for corded circular saws is 7 1/4″.
Cordless models are available, and these offer the benefit of portability and manoeverability in tight or confined spaces. The limiting factor in cordless circular saws is the cutting time. Wood is the only material I would recommended that you cut with a cordless circular saw since harder materials like masonry or metal require far more power and will have a tendancy to drain the batteries quickly. Cordless models are often smaller than the corded varieties, and this can be an advantage in tight spaces. Sizes available range range from 5 3/8″ to 6 1/2″.
Blade Capacity determines the maximum depth of cut a saw can achieve. For cuts perpendicular to the wood, most circular saws can cut through lumber that is approximately 3″ smaller than the blade. The larger the blade, the deeper the cut. The most common blade diameter is 7 1/4″. Most saws with blade capacities of 6″ or more can cut through 2″ dimensional lumber at a 45° angle in a single pass. A 5 3/8″ saw can cut through 2″ dimensional lumber in one pass at 90° but requires two passes at 45°. As a general rule, saws with smaller blade capacity weigh less and are easier to control.
Electric Brakes reverse the flow of electricity in the saw motor when the trigger is released. Reversing the current stops the blade’s momentum quickly. Electric brakes can stop the blade in as little as two seconds, compared to up to twelve seconds for a saw without this feature. This is a great safety feature to allow you to stop the blade immediately once you are finished with your cut.
Shaft Locks make it easier to change the saw blade. The shaft lock immobilizes the shaft and blade, making it much easier to change the blade. Without a shaft lock, two wrenches are required to change the blade. With a shaft lock, only one is required, since the lock keeps the blade still.
Choosing Circular Saw Blades
The blade performs a vital function for the circular saw: It is the part that actually makes the cut. Choosing the appropriate blade can save you time and can improve the appearance of the cut. Using the wrong blade, though, can waste money (quickly dulled blade) or even be a safety hazard. Different blades are available for different applications.
If you find yourself having to use excessive force to cut through the wood, have the blade sharpened (if available) or buy a new blade.
Here are a few common blades and their uses:
- Steel Blades are inexpensive and work well for cutting softwood; however, they dull quickly in hardwood.
- High-Speed Steel Blades are harder than steel blades and stay sharper longer.
- Carbide Blades have carbide tips attached to their teeth. They are more expensive than other blades, but they stay sharp much longer than steel or high-speed steel. You can identify carbide blades by the tiny “shoes” attached to every tip.
- Tile-Cutting Blades are specially designed for cutting ceramic tile. Better tile-cutting blades have diamond-tipped blades.
- Masonry Blades are made of abrasive material for cutting concrete, brick, cinder block and other masonry materials.
How To Use a Circular Saw
Always read the manual that came with your power tool! Always follow the safety percautions, especially while you are getting acquainted with your tool!
Tips for Perpendicular Cuts / Cross Cuts
Making cross cuts with the circular saw is quick and easy. The most important aspects to remember are to support your wood and to keep in mind which portion of the wood will be dropping once the cut is finished. You want to maintain control of the circular saw as the final section of the wood is cut through to prevent the saw from dropping towards your legs.
Long Cuts – Use a Straightedge
To cut accurate lines on large boards like plywood and MDF sheets, use a straightedge to guide your circular saw. Circular saws have a plate along which the saw glides. The width of this plate is usually different from the left or right side, but the measurement from the blade to the outer edge of the plate is constant. So if the distance from the blade to the outside edge of the plate is 2″, clamp a hardwood straightedge to your plywood exactly 2″ away from the line you want to cut along. Then run your circular saw with the plate pressed against the straightedge, and you will have a perfectly straight long line! Just be sure to keep in mind what part of your workpiece will be dropping when you finish your cut, or support your workpieces appropriately, to avoid any surprises.