Make this simple circular saw jig and every cut will be perfectly straight! Just clamp the jig to your board and slide the circular saw along the fence.
Cutting a piece of wood in a straight line seems simple enough. Just follow a line with the blade of your circular saw, right? But as you work your way down the board, the saw takes on a life of its own and you end up with a wonky edge.
By using a simple DIY circular saw jig, you can ensure that your cut will be straight and exactly where you wanted it.
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Inexpensive guides such as this one have a tendency to bow out in the middle, resulting in a less than straight cut. I own both the Rip Cut and the cheaper version, and I still go back to this very simple circular saw jig I made in my beginner woodworking class.
How to Build a Circular Saw Jig
Materials Needed for DIY Circular Saw Jig
Cut the plywood sheet into roughly one foot wide strips. There's no need to be exact. Just make sure that one piece is a few inches wider than your circular saw, including the motor.
With the saw unplugged, lift the blade guide up so that the blade is exposed. Place the saw on the larger piece of plywood, matching up the edge of the wood with the side of the blade.
Line up the other piece of plywood next to the edge of the circular saw base plate.
Remove the saw, then draw a line where the two plywood pieces overlap. Remove the top board, and drizzle wood glue all over that side of the board, leaving about an inch clear of the line.
Place the top plywood piece onto the glue, setting it about ½ inch away from the line you drew (towards the glued side). You'll see why later on. Clamp the pieces together, or place something heavy on top, and let the glue dry.
You'll notice that the bottom of the circular saw jig isn't even. Once the glue is dry, flip it over and trim off the excess with your circular saw. Don't worry if the edges don't exactly line up. You can sand it down later.
Every circular saw has a very slightly different width between the edge of the base plate and the blade, even among identical brands. In my beginner woodworking class, the instructor numbered every circular saw and its corresponding jig. Mixing up the saw and the jig would result in a cut that was slightly off!
Clamp your jig to your work surface, making sure to elevate it with a few scrap pieces of wood so you don't cut into the table. Line up the edge of your saw's base plate with the fence you created, then cut away the edge of the board.
Congratulations! You have two pieces of plywood glued together! So now what?
Here's an example. Say you're making this outdoor storage bench out of ¾" plywood. You've marked this particular piece with the line you need to cut, and an 'X' on the waste side of the board.
Elevate the board with a few scrap blocks of 2x4 so you don't cut into the worktable.
Then place the jig on the cut line, making sure that the saw blade will be on the waste side. Clamp the jig to the board at both ends, and then the board to the worktable so it doesn't move around mid-cut.
Before tightening the clamps, double check that the corner will be square. Place a speed square at the cut line and adjust the circular saw jig if necessary.
Finally, place the circular saw against the fence. Double check to make sure the clamps aren't in the way of the saw motor, then make the cut. Be sure to keep the saw flat on the circular saw jig and slide it slowly along the edge.
Ta da! A perfectly straight cut!
Of course, a table saw would make this cut in a fraction of the time it takes to set up this circular saw jig. But for a beginner on a budget, this is the perfect way to cut sheets of plywood or even dimensional lumber! See, you don't need lots of fancy tools to start woodworking!