To cut straight with a circular saw, do not follow a pencil line by eye. Clamp a straightedge guide to the board and run the saw's base plate along it. A homemade guide, made from a strip of plywood glued to a wider thin base, puts the blade exactly on your line. Support both sides of the cut and set the blade about 1/4 in below the wood.
A circular saw is one of the most useful first tools, and with a guide it can do much of what a table saw does. If you are still choosing tools, see our list of essential woodworking tools for beginners. If you have not used a power saw before, read the safety section below before your first cut.
At a glance
- Build time for the guide
- About 1 hour plus glue drying
- Materials
- Plywood or hardboard base, plywood fence strip
- Blade depth
- About 1/4 in below the board
- Good face
- Down (the blade cuts upward)
- Key safety rule
- Support both sides so the kerf cannot pinch
Beginner shortcut
Once you can cut straight, almost any project opens up. The TedsWoodworking plan library has thousands of projects with cut lists, including plenty of simple builds for basic tools.
Why freehand circular saw cuts wander
A circular saw sits on a flat base plate (the shoe). When you push it by hand, tiny side-to-side movements steer the blade. Over 8 feet, those movements add up to a wavy edge. Steering it back makes the blade bind, which can cause kickback. A guide removes the steering problem: the base plate rides against a fixed edge, so the blade can only go one way.
Straightedge guide options compared
| Option | Best for | Pros | Cons |
|---|---|---|---|
| Speed square held against the board | Crosscuts on 2x4s and boards up to about 10 in wide | Fast, no setup | Only short cuts |
| Clamped level or straight board | Quick one-off cuts | Uses what you have | You must measure the blade offset every time |
| DIY two-piece guide (below) | Plywood rips and long cuts | Edge of the guide = cut line, no offset math | One guide fits one saw and one blade |
| Store-bought clamp guide or track | Frequent sheet goods work | Ready to use | Costs more than a DIY guide |
How to build the straightedge guide
What you need
- Base: a strip of 1/4 in plywood or hardboard, 12 in wide and as long as your longest cut (96 in for full sheets, 48 in for a handy short guide). Make sure it is wide enough: measure from the edge of your saw's base plate to the blade, then add the fence width and an inch or two.
- Fence: a strip of 3/4 in plywood about 3-4 in wide, the same length as the base, with one factory edge. The factory edge from a sheet is usually straighter than anything you can cut freehand.
- Wood glue and short screws (shorter than the two layers combined, so they do not poke through the bottom)
- Clamps
Step 1: Attach the fence
Lay the base flat. Place the fence on top, along one long edge of the base, with the factory edge facing the wider part of the base. Glue and screw it down every 8-10 in. Wipe off squeeze-out on the factory edge so the saw slides smoothly.
Step 2: Trim the base with your saw
Clamp the guide to a scrap sheet or foam board so the wide side overhangs nothing you care about. Set your blade depth just deeper than the base. Run the saw along the fence, keeping the base plate tight against the factory edge. The blade trims the base, and now the cut edge of the base shows exactly where your blade cuts.
Step 3: Label it
Write your saw's name and blade on the guide. If you change saws or use a much thicker or thinner blade, trim a new edge or build a new guide.
How to cut straight with a circular saw using the guide
Step 1: Mark both ends of the cut
Measure and mark your cut line at both ends of the board. See our guide to measuring and marking wood accurately for a clean V-mark. Mark an X on the waste side.
Step 2: Support the work
Lay the board on a sheet of rigid foam insulation on the floor, or on several 2x4s across sawhorses so both the part and the offcut are supported. Never cut between two sawhorses with the middle unsupported: the board sags, closes the kerf and pinches the blade.
Step 3: Line up and clamp the guide
Put the trimmed edge of the guide exactly on your marks, with the guide sitting on the part you are keeping, not the waste. That way the kerf falls on the waste side. Clamp both ends firmly.
Step 4: Set the blade depth
Unplug the saw (or remove the battery). Set the blade so it reaches about 1/4 in below the bottom of the board, counting the guide's base thickness. A shallow setting cuts more cleanly and exposes less blade.
Step 5: Make the cut
Place the front of the base plate on the guide with the blade not touching the wood. Start the saw and let it reach full speed. Push forward at a steady pace, keeping the plate pressed against the fence. Do not twist the saw or pull it backward while it is running. At the end, release the trigger and let the blade stop before you lift the saw.
Straight cuts, real projects
Build furniture with just a circular saw
According to the sales page, most TedsWoodworking plans need only a saw, a drill, clamps and a sander, so a guided circular saw goes a long way.
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- Step-by-step diagrams for each build
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Circular saw safety basics
- Wear safety glasses and hearing protection every time.
- Clamp the work and the guide. Never hold a board with one hand while cutting with the other.
- Keep your body out of the saw's path. Stand slightly to the side, not directly behind the saw, in case of kickback.
- Check the lower blade guard springs back freely before each session. Never pin it open.
- Keep the cord behind you and clear of the cut line.
- Do not reach under the board while the saw is running.
- Unplug or remove the battery before changing blades or adjusting depth.
Tips for cleaner, straighter cuts
| Problem | Likely cause | Fix |
|---|---|---|
| Splintered top face | The blade cuts upward, tearing the top fibers | Put the good face down; use painter's tape on the cut line |
| Burn marks | Dull blade, or the kerf closing on the blade | Change the blade; support both sides of the cut |
| Cut drifts away from the guide | Base plate not held tight to the fence | Push forward and slightly toward the fence |
| Rough plywood edges | Blade with too few teeth | Use a finer blade with more teeth for plywood |
Quick crosscuts with a speed square
For 2x4s and narrow boards, you do not need the long guide. Hold a speed square's lip tight against the far edge of the board, slide the saw plate against the square's edge, and cut. Practice on scrap first, and check your saw blade is square to the base plate.
Before you start, make sure you are cutting good material: our guide on how to pick straight lumber helps you avoid warped boards. Then try your new skill on the 2x4 workbench plan.
Your guide is ready. What will you cut first?
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FAQ
Which side of the board should face up when using a circular saw?
The good side faces down. The blade spins upward through the board, so splintering happens on the top face.
How deep should the circular saw blade be set?
About 1/4 in below the bottom of the board. Deeper settings expose more blade and cut less cleanly.
Can a circular saw replace a table saw for a beginner?
For many projects, yes. With a straightedge guide it can rip plywood and boards accurately. A table saw is faster for many repeat cuts, but it is not needed to start.
Why does my circular saw kick back?
Usually because the kerf closes and pinches the blade, often from a sagging, unsupported board, or from twisting the saw mid-cut. Support both sides and keep the saw moving straight.
