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 guide, also known as a sled, you can ensure that your cut will be straight and exactly where you wanted it.
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There are several rip cut guides for circular saws on the market, such as the Kreg Rip Cut. But these guides only allow you to make cuts parallel to the edge of the plywood. Other guides such as this one can clamp at an angle, but require you to measure out the width of your circular saw for each and every cut. I own both of these guides, and I still go back to this very simple circular saw guide that I used in my beginner woodworking class.
Small sheet of 1/4″ plywood (You can use Home Depot’s project boards, such as this 2’x2′ one)
3 Bar Clamps (I love these quick release clamps from Harbor Freight)
Cut the plywood sheet into roughly one foot wide strips. There’s no need to be exact. Just make sure that one strip 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 the other piece of plywood up next to the outside edge of the 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 line. Be sure not to get glue too close to the line.
Place the top plywood piece onto the glue, setting it about 1/2 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 sit for an hour or so to let the glue dry.
Once the glue is dry, you’ll want to make the bottom of the guide flat. To do that, flip it over so that the bottom is facing up, and trim off the overhang with your circular saw. Don’t worry if the edges don’t exactly line up. You can sand it down later.
Now remember how I told you to glue the board about a half inch away from the line you drew? This is the part where you cut off that extra 1/2″ to create a custom sized guide for your particular saw. Every 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 each one corresponded to a matching numbered guide. Mixing up the saw and the guide would result in a cut that was slightly off!
Clamp your guide to your work surface, making sure to elevate it with a few scrap pieces of wood so you don’t cut into your table. Line up the edge of your saw’s base plate with the lip of the guide, then cut away the edge of the board.
Congratulations! You have two pieces of plywood glued together! So now what?
Here’s an example. Right now I’m working with 3/4″ plywood to make an outdoor storage bench for our front porch (project details coming soon!) I’ve marked this particular piece with the line I need to cut, and an ‘X’ on the waste side of the board.
I simply place the guide on the line I need to cut, making sure that my saw blade will be on the waste side. Then I clamp the guide to the board at both ends, and then the board to the worktable so it doesn’t move around. In this case, I was able to clamp the guide, board, support blocks and the worktable all together at both ends. You may have to lay the board across a corner of the worktable to get everything clamped securely.
I always elevate the board with a few scrap blocks of 2×3 so I don’t cut into the worktable surface. I place a block under each clamp and one under each corner of the board. It doesn’t matter if I cut into the blocks accidentally, but I like my nice flat tabletop!
Before tightening the clamps, I double check that the corner will be square. Place a speed square at the cut line and adjust the guide if necessary.
Finally, I place my circular saw against the lip of the guide, double check to make sure the clamps aren’t in the way of the saw motor, and make the cut. Be sure to keep the saw flat on your guide board and slide it slowly along the edge of the guide.
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 guide. But like a lot of people, I don’t have room or the budget for a table saw in my workshop. This guide could even be used in place of a miter saw for cutting lumber. See, you don’t need lots of fancy tools to make a project out of wood!