When I have to rip long pieces of 2x framing lumber with a circular saw, I use a pair of 3/4-in. plywood blocks to help me secure the work. The blocks are the same width as the lumber being cut. For instance, the 5-1/2-in. block shown in the drawing is for a 2×6. I tack each block to a sawhorse with two 8d nails, leaving the head of the nail about1/4-in. above the block. Then I snip each nail head off with a pair of side cutters. This leaves about 1/2-in. of nail shank protruding from the block. These protrusions are sharp enough to penetrate a piece of softwood, and long enough to hold it in place while I make my rip cuts. I set the blade depth so the cut enters the block, but not the sawhorse.
P. J. Woychick, Boise, ID