Tuesday, February 27, 2007

Thoughts on the Circular Saw

The circular saw is a simple yet integral part of any woodworker’s arsenal of tools. We recently reviewed two of these staple tools, but we had some additional thoughts.

Head To Head
After reading my review of my Skilsaw 5750-01 and Brit’s review of his Porter-Cable 347K you will see that we both like our respective circular saws. Brit and I have also had the opportunity to use the other guy’s circular saw on occasion, and it would be safe to say that we each like the other guy’s saw as well. We both agree that if you are going to be like Brit and use your saw for something as taxing as cutting stone than you probably should pony up the extra cash and get a saw with the biggest motor. On the other hand, if you are going to use your saw more conventionally, meaning cutting wood and composite materials, than save some money and go for the Skilsaw. You can use that extra $50 to $75 to buy a good blade or invest in another tool.

Sidewinders & Worms
Circular saws fall under two main categories, direct drive and gear drive. A direct drive saw, commonly called a sidewinder, is the standard circular saw that you see everywhere. Both my Skilsaw and Brit’s Porter-Cable are sidewinders. These saws have the motor mounted on the side of the blade, hence the sidewinder moniker. Also, the blade is mounted on shaft which is part of the motor, so every revolution of the motor equals one revolution of the blade. This is where the direct drive part of the name applies.

Gear driven circular saws are known by many names: worm drive, worm gear, and hypoid. Gear driven saws are the heavy-duty workhorse of many professional framers and carpenters. These saws feature a transmission between the motor and saw blade consisting of a series of gears. A quick way to spot a gear driven saw is by noticing that the motor is placed behind the blade rather than to the side of it. Also, a worm gear saw requires regular lubrication of its gears, while a hypoid saw has a sealed transmission that is permanently lubricated.

So what is the real difference? Sidewinders are generally lighter and less expensive than gear driven saws. That being said, they are more prone to kickback as well. Gear driven saws are heavier (not always a bad thing), have more torque, and have a longer lifespan. Although they are less likely to kickback, gear driven saws are prone to a sharp twisting motion when the saw is started. Pros call this saw buck, the powerful torque of the motor causes it. Which saw should you get? If you are going to be using your saw frequently and on a daily basis then get a gear drive, otherwise a sidewinder should suit you fine.

Circular Saw Safety
I have read estimates that circular saws are responsible for the vast majority of serious home improvement accidents. I have no idea how true this is, but it is logical considering how common these tools are. Besides my mantra of always using common sense and good judgment, here are some solid safety tips. Always wear safety glasses as circular saw can kick up quite a bit of dust. Using hearing protection and a dust mask is also a pretty good idea. Always be aware of where the power cord is so that you do not cut it with the saw of trip over it while cutting. Never remove or disable the safety guard on your saw. Just like a table saw, a circular saw can kickback. Kickback will cause the saw to jump backwards rather violently. Hold the saw tightly and keep both hands on the saw as frequently as possible. If both hands are on the saw and kickback occurs neither hand can be cut. Always support large sheets of material, such as plywood, to prevent the material from bending or sagging as you make a cut. This will reduce the possibility of kickback.

Cutting Tips
Before making a cut set the depth of the cut so that the bottom teeth on the blade just barely stick out past the face of your material. This exposes less of the blade for safety and it will help to reduce tear out.

When ripping longer boards or sheets an aluminum cutting guide is a great way to get a perfectly straight cut. Some cutting guides have integrated clamps while are just a flat piece of metal that you can clamp to your stock with spring clamps or c-clamps.

When cross cutting, a rafter square or Chopshot makes a quick guide for a perfect cut.

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