How to use your circular saw safely with a few tips and techniques.
Circular saws can be extremely helpful, or extremely dangerous depending on how you use them. Fortunately there are a few tips and techniques you can use to make using your circular easier and safer.
Circular Saw Parts
Setting the Proper Blade Depth
Setting the blade on your circular saw too deep causes several problems. A blade that is set to the incorrect depth exposes more of the blade when cutting which can cause it to cut through your saw horse or other material. The saw is more likely to bind and kick back if the blade is too deep. Aside from these safety issues, circular saw blades cut more efficiently when properly set. To determine the correct blade depth, unplug the circular saw and hold it alongside the board with the blade guard lifted up. Loosen the depth lever or knob and slide the saw's base until the blade extends about 1/4 to 1/2 in. below the board. Tighten the lever, release the guard, and plug the saw in to make your cut.
Always make sure the end of the board you're cutting is free to fall or move away. When making rough cuts in framing lumber, let the cut end fall. Keep in mind that allowing the free end to fall away will cause the last piece to take a splinter of wood along with it. To avoid this splintering when making cuts for more finished projects you need to support the board continuously by placing a scrap piece of wood under the piece you are cutting to support the weight.
Plywood cutting technique
Crosscutting plywood, which is cutting across the width of a sheet of plywood – 48 inches max, without supporting it across the full length can cause the saw to bind as the weight of the saw causes the plywood to cup or the plywood veneer to tear or splinter as the free end falls. If you're using sawhorses, simply place a pair of 2x4s along the length of the sheet.
It is important to never support a piece of wood you are cutting only on the ends. Just like unsupported plywood, as the cut nears completion, the board bows downward which pinches the blade making the saw or board to kick back. Not only can serious injuries result, the saw usually jumps out of the cut and tears the face of the board you are cutting.
Securing Wood for Rip Cuts
In most cases, a table saw is a better choice for ripping lumber than a circular saw. A circular saw will work fine if the rip is for framing and does not need to be very precise or you don’t need to make a lot of them. The key to making a successful rip cut is to hold the board in place while you rip it. Clamps will get in the way unless the board is very wide, but a good alternative to clamping is to tack the board down to your sawhorses. The nails can remain above the surface of the wood if the saw blade shoe clears it, but the nail or screw can be flush with the surface of the board if you can remove it easily. To reduce damage to better-quality boards use finish nails and pull them through the back of the board when the rip is complete.
Blade Guard Techniques for Angled Cuts
Most circular saws have blade guards that retract when making an angled cut. While they do work, it is often better to get the cut started if hold the blade guard clear of the board before starting the cut. After you have moved through the board a few inches slowly release the blade guard so it rests on the board. The reason this technique is useful is that the corner of the wood can become lodged inside the guard causing the saw to become stuck or cause the blade to drift off the mark.
How to Cut Heavy Boards without Sawhorses
When you're cutting joists or other heavy pieces of lumber, it's often easier to cut them close to the ground than lift them up onto sawhorses. The best way to do this is to rest the board on your toe and lean it against your shin. Then align the saw with your mark and let gravity help pull the saw through the cut. Keep the saw cut at least 12 in. from your foot and leg.
Use your Fingers as a Rip Guide
You can make long narrow rip cuts with a circular by using your index finger as a guide. Align the saw blade with your mark on the board and then pinch the saw base at the front corner with your thumb and index finger. Let your finger ride along the edge of the board to guide the cut. Your finger will be close to the blade but you will be safe as long as you hold onto the saw before turning it on and don't release it until the blade stops.
Always replace your saw blade when your cuts begin to drift away from the line or the cut appears to be wavy. Use high quality carbide-tipped saw blades for framing and plywood cutting blades for cutting trim and plywood. Combination blades are useful to use when your are not making fine cuts or don't have time to change your blade.