Even with access to a nice table saw, cutting full sheets of plywood can be dificult. Here is an alternate method I like to use to break down sheets to pieces of a more manageable size. It also works well as a way to accurately cut plywood if you don’t have a table saw.
I set my shop boxes to a lower height, and turned the I-beams 90 degrees. This puts the plywood at a convenient height, and the saw blade will nick the edges of the beams rather than cut a slot across the flat surfaces. You can also do this with regular sawhorses, with two or three sacrificial 2 x 4s spanning them. You want the plywood to be fully supported as you make the cut , you don’t want the cut off piece to drop as the cut nears completion.
In addition to the circular saw, all I need is my tape measure and framing square, a shop-built jig, and a couple small clamps. For a minimal investment, I can cut plywood as accurately as I can with a table saw, though it does take a bit longer.
The key to success is careful measuring and layout, and the jig that guides the saw. The jig is made from two pieces of 1/2″-thick Baltic birch plywood. The bottom piece is about 8″ wide, and the top piece is about 1-1/2″ wide. Both pieces are about 60″ long. The top piece is glued to the bottom one, leaving about 1″ of space for the clamps. The only critical dimension is to leave a space from the edge of the skinny piece to the edge of the wide piece that is bigger than the distance from the edge of the saw’s baseplate to the edge of the blade.
After the glue has dried, run the saw against the fence, trimming off the bottom piece of plywood. The jig is now set so that the blade of the saw will cut precisely to the edge of the jig. To use it, simply clamp the edge of the jig to your layout line, keeping the edge of the jig on the edge of the piece you want to keep. Set the depth of the saw blade so that it will be about 1/4″ below the bottom of the plywood when you cut. Set the edge of the saw’s base against the edge of the fence and make the cut.
Here are the completed stands with the plywood tops and shelves in place. I glue the plywood down with yellow glue, using narrow crown staples to fasten them to the edge of the board below. You can also use nails or screws.
If you make any of these for your own shop, or come up with a variation or improvement, send me a photo of the results. I’ll post the interesting ones here on the blog.