The safe operation of a circular saw requires that the operator exercise extreme caution whenever using it. A circular saw is defined as a portable hand-held electric saw generally used for cutting wood up to a few inches in thickness. Also known as a skilsaw, the original portable circular saw was introduced in 1924 by a company which renamed itself Skilsaw Inc., by which it got its name.
Before Making a Cut
Several precautions must be taken to guard against injury when using a circular saw. Always make sure that the saw blade is kept sharp. Have extra saw blades on hand and replace the blade when the cutting saw blade begins to bind or kick for no reason. Do not discard used saw blades; they can be re-sharpened. Wearing safety goggles is highly recommended when cutting lumber with a circular saw to protect against flying fragments or splinters. With the power cord unplugged, adjust the blade depth so that the saw blade penetrates ¼ inch below the board being cut. Make sure that the blade guard is working properly. Never let the exposed saw blade rest on any surface.
Whenever possible, cut boards on sawhorses. Lay the board across 2 sawhorses so that the center of gravity is between them, and cut the board where it overhangs past each sawhorse. Saw the board cleanly and allow the scrap piece to fall when cut. With your free hand, lightly apply downward pressure on the scrap piece if the saw blade begins to bind. If a sawhorse is not available, do whatever is necessary to make sure the board is held firmly and motionless while being cut without endangering yourself. Do not cross-cut a board less than 1 foot long. If the saw blade begins to bind, allow the blade to come to a full stop and lift it out of the cut; do not pull the saw backward through the cut.
“Ripping” a board is cutting with the grain along the long dimension of a board. If you are ripping the length of a board, tack (drive a nail half-way) or clamp the board straight and parallel onto the sawhorse so that the cut line is clear of the sawhorse. You may want to hold the power cord with your free hand so it doesn’t snag on the board or get cut by the rotating blade. If you are cutting several pieces of plywood to the same dimension, you can clamp or nail them together and adjust the blade depth to cut them simultaneously.
Always make sure the saw blade is rotating at full speed before you begin a cut. Also, make sure the plate or “shoe” is tightly set to the appropriate depth and hold it flat against the board when making a cut. When cutting, align the pencil line with the guide and watch the line, not the saw blade. Cut so that the thickness of the saw blade is just to the scrap side of the line, and leave the line visible on the board to get an accurate cut.