While circular saws are generally used for rougher cutting tasks, they can also be used to make fairly precise 45-degree angle cuts with a little preparation and know-how.
45-degree angle cuts are used in all types of carpentry and woodworking applications, from installing window trim to making wooden boxes. There are two basic types of 45-degree angle cuts one can make with a circular saw – the miter cut and the bevel cut.
I’ll explain how to make both of these in step-by-step detail, so you’ll be able to replicate the process yourself for whatever project you’re working on.
Jump To:
Tools & Materials
- Circular saw
- Speed square
- Carpenters pencil
- Clamps
- Sandpaper or file
Cutting a 45-degree Bevel
Bevel cuts are commonly used to form tight clean corners when installing baseboards and trim or when building cabinets or boxes. They have a nice clean aesthetic and add a degree of sophistication to any project.
While these cuts are typically made using a compound miter saw, you can also cut a 45-degree angle bevel using a circular saw.
The key to getting an accurate bevel is using a guide that’s clamped in place while you make the cut.
This will ensure your saw cuts straight all the way through the cut and won’t wobble or slip towards the end.
Step 1: Measure and Mark Cut Line
First up, you’ll want to measure and clearly mark your cut line on the wood’s surface. Use a speed square to make a nice clean line that’s easy to see.
Step 2: Position and Clamp Speed Square
Next, you’ll want to place the saw on the wood surface and line up the cut line you just drew with the 45-degree kerf indicator line stamped on the shoe. You should see two different lines on the shoe – one for 0° and one for 45° – we’ll be using the 45° one as we’re going to be cutting at a 45° bevel angle.
Now butt the speed square right up against the shoe and clamp it in place. This will serve as the guide for our bevel cut so it needs to be held firmly in place.
Step 3: Adjust the Saw’s Bevel and Depth
Now we need to adjust the saw’s bevel angle as well as the blade depth.
First, locate your saw’s bevel angle adjustment at the front and loosen the mechanism so the saw tilts away from the shoe. Some saws (like mine) will have detents at 22.5° and 45° as these are common angles to cut bevels.
Set the bevel angle adjustment to 45° and then tighten the lever firmly.
Now we need to adjust the saw’s cutting depth so that the blade just barely sticks out below the cutting surface. This isn’t necessary if you’re making a rough cut, but it will result in a cleaner cut otherwise.
Find the depth adjustment knob on your saw (typically at the back beside the cord) and loosen it. Then slide back the blade guard so you can see the blade and set the depth so the blade extends just past the wood by a 1/4-inch or so.
Step 4: Make the Cut
Now it’s time to make the cut. Line up the saw so the shoe butts up against the edge of the square.
You’ll want to be smooth and deliberate when making the cut to avoid any slipping, especially as you finish the cut, as this is where people have a tendency to twist the saw. Be sure to keep the shoe aligned with the edge of the square throughout the entire cut to avoid inaccuracies.
Step 5: Sand the Edge
Now clean up the edge of any little splinters with a piece of sandpaper or file and voila – you’ve cut yourself a nice clean 45-degree angle bevel with a circular saw.
If you wanted to rip cut a bevel lengthwise rather than cross-cutting, the process is essentially the same, but you’ll need to use a longer cutting guide. A straight edge guide or a rip fence can both work well for this.
Cutting a 45-degree Miter
45-degree miter cuts are commonly used for making boxes, doors, windows, and decks, and picture frames.
Once again, the key to making an accurate cut is using a guide clamped in place to control your cut all the way through. The overall process is similar to the bevel cut above, but in this case, we’ll be cutting with the blade at 0° rather than 45°.
Step 1: Measure and Mark Cut Line
Just like the above process, the first step is to measure and mark the cut line. Luckily, marking a 45° line is easy with a speed square, as the angled edge is a 45° angle.
Step 2: Position and Clamp Speed Square
Now you’ll want to place the saw on the work surface and line up the cut line with the 0° indicator on the shoe. Then, butt the speed square up against the edge of the shoe and clamp it in place.
Once again this will serve as our guide to ensure we cut cleanly and accurately.
Step 3: Set the Blade Depth
As we’ll be cutting with the blade perpendicular to the work surface, there’s no need to adjust the bevel angle.
Set the blade depth by sliding back the blade guard and butting the blade against the wood. You want to set the depth so that the blade extends about a 1/4-inch past the bottom.
Step 4: Make the Cut
Now line up your saw with the edge of the speed square and carefully guide the saw as its cuts through your material.
There will be some resistance from the blade guard initially, so push gently but firmly to retract the guard.
Step 5: Sand & File
Now all that’s left to do is clean up the cut with a little sandpaper or a wood file.
Cutting a Compound Miter
A compound miter is sort of like the above two cuts combined into one. You’ll be cutting both a miter and a bevel at the same time, which results in a surface that’s angled on two edges.
These cuts are typically made with a compound miter saw, but you can make one with a circular saw if needed. It likely won’t be as precise as it would if you used a miter saw, but you can still get a decent result.
To simplify things, for this example both the miter angle and the bevel angle will be cut to 45° angles.
Keep in mind you can cut the miter angle to whatever angle you like, and the bevel angle to any angle as long as your saw’s bevel angle adjustment goes that far (mine goes to a max of 57°).
Step 1: Measure and Mark Cut Line
Once again, you’ll want to clearly measure and mark your cut line using a speed square and carpenters pencil. Assuming you’re cutting the miter at a 45° angle, the speed square will serve as a perfect guide.
Step 2: Position and Clamp Speed Square
Now, you’ll need to place your saw’s shoe on the wood surface and align the 45-degree indicator line on the shoe with the line you drew in the previous step.
Then, butt the speed square right up against the shoe and clamp it in place. This will serve as the guide for our cut so it needs to be held firmly in place.
Compound miter cuts are a little tricky to get right, so make sure the speed square is firmly clamped and has absolutely no play to it whatsoever.
Step 3: Adjust Bevel Angle & Blade Depth
Next, you’ll want to set the saw’s bevel angle adjustment to 45°. Loosen the adjustment knob at the front, find the 45-degree indicator, and then tighten it up.
After that, you can set the blade depth so the blade extends out just below the bottom of the wood surface.
The reason you adjust the blade depth after setting the bevel angle is that the blade depth will actually reduce the higher you set the bevel angle.
Step 4: Make the Cut
Now, carefully line up the edge of the saw with the guide and cut through your material slowly and deliberately. Watch out towards the end, as the saw can wobble as you finish the cut if you’re not careful.
Step 5: Sand the Edge
Last up, you can clean up any little splinters with a piece of sandpaper or file.
Tips for Accurate Cuts
- Use a sharp ‘finish’ blade in your saw instead of the framing blade it comes with. This will help make the cuts cleaner and avoid splintering.
- Try to keep both hands on the saw through the cut. This will help guide the blade straight and will also ensure you have a good grip on the saw in case of kickback.
- To get an accurate cut you’ll want to make sure you cut slightly outside the cut line. You can always sand it down a bit if it’s too big, but you can’t add back material.
