Track saws are one of the hot new things in woodworking. I guess they have been around for a while, but it seems like every power tool company has jumped on the bandwagon. They look handy and appear perform nice clean cuts with the way the track backs the saw blade. They are all really expensive though.
A cheap substitute is to use a clamped straight edge to run your saw or router up against. It works, but doesn’t prevent you from wondering away from the guide and doesn’t back the cut. I have a few clamping straight edges from a company called E Emerson. They sell a saw plate to attach your own circular saw to their track, but it has abysmal reviews and doesn’t back up any of the cuts.
Instead I am going to 3D print an adapter to hold a sheet of 1/2″ plywood to act as a moving saw plate base. I took a pile of measurements and after a few iterations came up with the right design that would hug the tracks available on the clamp.
I had some phenolic faced plywood left over from making my own table saw inserts. I cut the plywood to the rough size of my circular saw base, and attached two long guides.
To attach the saw, I tried printing some different bracket styles, but was never happy with how they held. Instead I found a 1/4″-20 threaded hole in the base near the front to take advantage of (I think it was for some kind of moveable crosscut guide you could buy), and just drilled a hole in the back. It worked out though, the ribbing in the saw plate holds a nut perfectly. I counterbored holes in the bottom to keep the screw heads from interfering with the plate’s movement.
The saw is well fixed now and ready for me to plunge the blade through. With this setup I cut a slot that is perfectly sized for the blade. Now any cutting I do will be well supported and have little to no tear out. It is like a moving zero clearance insert.
It just so happens that I had a full sized sheet of plywood that required crosscutting down to reasonable sized for a project. Here is the setup ready for its first cut.
Everything went smoothly until I got to the end. The guides got hung up on the folding clamp lever (blue and pointing downward in this picture). It left me with a few extra inches of plywood still left un-sawed. Kind of a bummer.
I regrouped and decided to move the front guide back until it touched the rear one, this would buy me a little. It still wasn’t quite enough, and some heavy sanding was required. Once I shaved it down at an angle I was able to make a complete cut across the plywood.
Once I got the cutting part figured out I wanted a set of guides. Setting up one of these straight edges always involves a bit of math. You need to know the distance from the blade to the edge of the saw plate, and are you concerned about the inside or outside edge of the saw kerf? I made a set of plywood blanks that show exactly where your cut will land. Now you can make a mark. line the blanks up, and voila. Just line it up and that is where the cut will happen.
I made a number of different length guides all designed for 1/2″ plywood and uploaded them to thingiverse.