Set the Blade Depth to Just Clear the Plywood Thickness
Adjust the depth of your blade so that no more than half a carbide tooth falls below the bottom of the plywood. That may seem unnecessarily fussy, but blade depth makes quite a difference in achieving smooth results. This setting lets the teeth shear the wood fiber rather than chop it, and it helps stabilize the blade (less vibration). Both factors minimize saw tooth marks. The deeper you set your saw blade, the more marks you get.
Set the saw along the plywood edge, lift the guard and look closely as you set the depth. It’s also a good time to check the blade for chipped or missing teeth. A blade with bad teeth or wood pitch buildup won’t cut cleanly. Also note that a circular saw cuts on the upstroke, which often splinters the top edge (veneer) slightly. The bottom edge usually remains splinter-free. So always cut plywood with the good side down.
Make the Cut at a Steady Speed Without Stopping
Cutting speed depends on many factors, including the type and sharpness of the blade and the type of plywood you’re cutting. In general, a sharp blade should flow through the wood with little force, as if it’s melting the wood away. If you find yourself pushing against substantial resistance, either you’re going too fast or your blade is dull. Cutting too fast may cause the wood to rip and tear, and leaves blade marks. Going too slowly may cause the blade to overheat and burn the wood.
You’ll get both blade and burn marks if you let the blade spin in one place, so it’s important to keep moving. This is where working on the floor pays off for long cuts. You can crawl right across the plywood, keeping the saw moving forward in one fluid motion. And you don’t have to bend or stretch into an awkward position.
Watch for Cord Snags
If a cord gets hung up, it can ruin a cut. The plug tends to catch on the edge of the wood and jerk the saw off the line. Sometimes the saw even comes unplugged. Be sure to set enough slack on top of the plywood so you don’t get hung up. Also, be sure to keep the saw going all the way through the end of the cut.