Circular saws fitted with standard 7 1/4-inch blades have a maximum cutting depth of about 2 1/2 inches (2 1/8 inches is typical for smaller-bladed cordless saws). That’s deep enough to make one-pass cuts through 2x (1 1/2-inch-thick) lumber, but it’s not enough for thicker stock, like 4×4 posts and 6×6 landscape timbers. Cutting these hunks of wood requires a few more passes and the help of a speed square.
1. Mark the cutline on one face of the post, using the square to guide the pencil. Place the saw’s shoe flat on this face, and line up the blade with the cutline. Hook the square on the corner of the post and slide it against the shoe, as shown. Hold the square tight, pull the saw away from the wood slightly, then pull the trigger. Make the cut using the edge of the square to guide the saw in a straight cut.
2. Rotate the post toward you (a). Now use the kerf to align the square: Place the stopped blade in the kerf (b), and put the square against the saw’s shoe (c). Hold the square tight, pull the blade out of the kerf, then pull the trigger and make the cut, using the edge of the square to guide the saw. Rotate the post toward you again, and repeat this step to finish cutting through a 4×4.
3. For larger timbers, rotate the timber toward you again, set the blade in the kerf, and make a fourth cut as before. Then take a handsaw (or a reciprocating saw with a long blade) and cut through the untouched wood at the center of the timber. The kerfs will help guide the blade as you saw.