By Paul Bianchina
If there is a single power tool that is universally accepted as a necessity by carpenters everywhere, it would be the circular saw. Versatile, hardworking and tough, for many professional carpenters a good circular saw is almost an extension of their hands.
Circular saws are most commonly referred to by the diameter of the blades they use, and range from trim saws with tiny 4" blades to massive beam-cutting saws with 16 1/2" blades. For the professional carpenter, however - and to fit the needs of most homeowners - the 7 1/4" circular saw is the accepted standard. It is here that you will find the greatest selection of saws, blades and accessories, and a range of prices that will fit any budget.
What to Shop For
Seven and a quarter-inch circular saws range in price from $20 to more than $150, and as with most tools, you definitely get what you pay for. At the lower end you have saws made almost entirely of plastic, with underpowered, low-torque motors and very questionable accuracy. At the upper end, there are a wide range of professional quality saws with power and accuracy to spare.
As with any tool, the best rule of thumb is to buy the best you can afford for the job you need to do. Spending $110 to $150 on a professional grade saw will reward you with a tool that will last several lifetimes. Here are a few things to look for:
- Power: For circular saws, power is rated in amperage draw for the motor. Lower end saws will draw around eight or nine amps, while the upper end ones will typically be in the 13- to 15-amp range. The more power the saw has, the less resistance it has when cutting, making it easier and safer to use and extending its lifespan considerably.
- Torque: Torque is the ability of the motor to transfer its electrical power to rotating the saw blade - the greater the torque, the more rotational power the blade has. Again, as with the electrical power, more torque makes the saw easier and safer to cut with. Some types of saws utilize a blade that is coupled directly to the motor, which cuts down on weight and cost but typically reduces the amount of torque generated. Most pros who are looking for saws that cut quickly with maximum power will opt for a worm-drive saw, a design in which the motor's power is transferred to the blade through a pair of worm gears - this creates additional torque, and also allows the motor to be positioned in such a way that the saw is more streamlined and easier to maneuver.
- Weight: The more you intend to use the saw over an extended period of time - framing or deck construction for example - the more the weight of the saw becomes a factor. To achieve the toughness and power of the professional-grade saws, heavier motors are used, along with tough steel gears and mostly steel construction. All of this adds weight to the saw. A good worm-drive saw weighs in around 13 or 14 pounds, so be sure and get a couple of different saws in your hands to test the weight and the overall feel of them before making your selection.
Blades and Accessories
The power of a circular saw is only part of the story -- choosing the proper blade is the rest of it. And when it comes to blades, there are a staggering number of choices and price ranges to select from. Always choose the right size blade for your saw, make sure it is rated for your saw's RPM (revolutions per minute - a rating of blade speed), and has a tooth pattern that's right for what you intend to cut.
At the low end you have blades made from high-speed steel with only around 10 to 12 teeth. Blades such as these are inexpensive, but the cuts are rough and the blade is not really worth having sharpened.
For a little more money, around $12 to $18, you can purchase carbide-tipped blades with 20, 24 and even 36 teeth. The carbide tips on the blade are sharper and cut easier, and allow the blade to be sharpened several times for greater economy. The more teeth a blade has, the smoother the resulting cut will be. For general framing use, the 24-tooth blade is a great choice, while a 36-tooth is good for plywood, particleboard, and most other sheet materials when a smooth edge is important.
Most circular saws will also accept specialized blades such as carborundum wheels and diamond blades for cutting masonry, stucco, ceramic tile and some types of metal. Follow the specific instructions from the manufacturer of both the saw and the blade for proper selection and use.
No matter what type of saw and blade you select - use them safely! Always wear eye protection; do not use an extension cord unless it's properly grounded and of the correct size for the amperage of your saw; keep the saw clean and inspect it regularly for damage and loose blades; never attempt to defeat or alter the blade guard; and carefully follow all of the manufacturer's recommendations.
. Questions of a Do It Yourself nature should be submitted to our "