Learn the Technique to Achieve Precise Cuts with a Circular Saw and Speed Square for Quick Accuracy
Looking for more precise cross and miter cuts without breaking the bank on a miter or track saw? Here’s a handy tip on how to achieve straight cuts using just a circular saw and a speed square.
What You’ll Need
- Circular saw
- Rafter Square (Speed Square)
- Tape measure
- Pencil or pen
If you don’t have an arsenal of professional-grade tools, don’t worry. You can still achieve flawless 90° and 45° cuts in wood without spending a fortune. All you need are a circular saw, a speed square (also known as a rafter square), a tape measure, and a pencil.
Know the terms: “Speed square” and “rafter square” refer to the same tool. Swanson made rafter squares famous, and many people commonly refer to all rafter squares as Speed Squares. Throughout this article, we use these terms interchangeably.
Setting Up
Start by measuring where you want to make the cut and mark it with a pencil. For 90° cuts, you can mark it anywhere across the width of the board. When it comes to straight 45° cuts using a circular saw and speed square, you have the flexibility to mark the longer or shorter edges based on your project’s requirements. However, we typically recommend marking the longer measurements.
Even before you bring out the saw, your rafter square will serve as a marked straight edge, ensuring more accurate cuts. Making a 90° crosscut is a breeze—just align the square and draw a line straight across your mark.
For 45° miters, remember whether you marked the shorter or longer end. If you notice that the corners of the square are oriented incorrectly, simply flip it over.
Making the Cut
Now that you have the perfect marks, you can choose to freehand the cut if you’d like. However, using the rafter square as a guide will guarantee the most accurate results.
Take into account the offset of your circular saw shoe. The easiest way to do this is by placing the square on the board, aligning the saw shoe with it, and sliding the two pieces until the blade aligns with the cut line.
Hold the board firmly in place with one hand, pull the saw back slightly so the blade doesn’t touch the wood, pull the trigger to spin the blade at full speed, and start cutting while applying light pressure to ensure the saw stays on track with the square.
A Few Points to Consider
Depending on whether your saw has a right or left blade and how you’re most comfortable cutting, you may encounter issues with the motor housing hitting the board. In most cases, you just need to set the blade depth slightly shallower to allow for a full, unobstructed cut.
However, this cutting method does have some limitations. It only allows for 90° and 45° cuts. If you need to make other common miter angles, you’ll have to find alternative techniques. While you can accurately mark other angles with your square, it becomes challenging to hold the square firmly without moving it as you cut.
Another consideration is the depth of cut. Most standard 7 1/4-inch circular saws can cut up to 2 1/2 inches deep, which is sufficient for cutting through a double layer of material. Even the 6 1/2-inch models can achieve this depth. Although there are high-capacity circular saws capable of cutting 4x material, they are not commonly available for DIYers. Additionally, remember to exercise caution when handling larger saws!
Lastly, consider the size of the speed square itself. A typical 7″ square allows for two cuts on boards up to 2 x 8, while a 12″ rafter square covers the entire range up to 2 x 12. Having both sizes is advantageous, and you can find good quality squares for less than $20 each.
If you have any questions or feedback, feel free to leave them in the comments below. And as always, thanks for reading!
Check out the tools we used in this article:
