Guards and kickback on a circular saw

A portable circular saw has a guard above the shoe and a lower guard over the teeth. The lower guard is the one that moves. You push the saw into the wood, that guard lifts, and the teeth do the cut. When the blade leaves the cut, the lower guard has to snap back and cover the teeth. If it stays open, the teeth are bare while you set the saw down or turn with it. Do not pin the lower guard open with a wedge, a nail, or a wire. If the guard is slow, bent, or packed with dust, tag the saw. Get one whose guard snaps shut on its own.

Set the blade depth so the teeth only just clear the bottom of the board. A blade that hangs far below the board leaves more tooth in the open if the guard is slow, and it grabs harder. Support the board so the cut does not close on the blade. A board stretched between two horses can sag, and the kerf pinches the blade. That pinch is what throws the saw back at you. Put the support so the piece you keep and the piece you cut off both stay put until the cut is done. Do not let the offcut drop and twist the blade in the middle of the cut.

Stand out of the kickback path. Kickback throws the saw back toward your body, or it throws the board. Do not stand in a straight line behind the blade. Set your feet to the side so a sudden throw does not hit your stomach or your thigh. Keep your hands on the handles the saw was built with. Do not reach under the board to catch the offcut while the blade is turning. When you change the blade, unplug the saw first. A saw that is still plugged in can start if the trigger gets bumped while the guard is held up and your fingers are on the teeth. Put the plug where you can see it, then change the blade.