When you walk into a workshop or browse an online store for a new blade, the sheer variety of options can be overwhelming. You’ll see numbers like 24T, 40T, or 60T plastered across the packaging, alongside technical terms like "thin kerf" or "full kerf."
For the uninitiated, these might just seem like marketing jargon or minor details. But for the professional tradesperson, these specifications dictate everything. They determine whether you get a rough, splintered edge that needs hours of sanding, or a glass-smooth finish ready for glue.
Understanding the physics of your circular saw blade—specifically the tooth count and the kerf width—is the difference between fighting your tool and having it work as an extension of your arm. In this guide, we dive deep into how these two critical factors impact your cutting performance across different materials.
The Science of Tooth Count: More Isn't Always Better
There is a common misconception that a blade with more teeth is inherently "better." In reality, tooth count is about application, not hierarchy. The number of teeth on your circular saw blade directly influences the speed of the cut and the quality of the finish.
Low Tooth Count (18T - 24T): The Ripping Specialists
Blades with fewer teeth have larger gullets (the deep spaces between the teeth). These are designed for "ripping"—cutting along the grain of the wood.
- Speed: Because there are fewer teeth engaging the wood at any one time, there is less friction. This allows you to push the saw through the material quickly.
- Waste Removal: The large gullets are essential for clearing the long, stringy fibres produced when ripping timber. If the gullets were small, they would clog instantly, causing the blade to overheat and burn the wood.
- Finish: The trade-off is the finish. A 24-tooth blade leaves a rough edge with visible saw marks. This is fine for framing stud work where the cut will be hidden behind drywall, but unacceptable for furniture making.
Medium Tooth Count (36T - 40T): The General Purpose Solution
Often called "combination blades," these attempt to bridge the gap. They typically feature groups of teeth separated by deeper gullets.
- Versatility: They can rip reasonably well without burning (provided the stock isn't too thick) and can crosscut (cut across the grain) with an acceptable finish.
- The Compromise: They won't rip as fast as a 24T blade, and they won't leave as clean an edge as a 60T blade. However, for a contractor who doesn't want to change blades five times a day, they are the ideal workhorse.
High Tooth Count (60T - 80T+): The Finishing Experts
When you are cutting across the grain (crosscutting), cutting plywood, or working with melamine, you need a high tooth count.
- Cut Quality: More teeth mean each tooth takes a tiny "bite" of the wood. This severing action is much gentler, drastically reducing the chance of tear-out or splintering on the surface.
- Speed: Because the gullets are small, these blades cannot clear dust quickly. You must feed the saw slowly. Pushing a high-tooth blade too fast will cause friction, burning the wood and dulling the carbide tips rapidly.
Understanding Kerf: The Width of the Path
"Kerf" refers to the width of the material removed by the blade during the cut. Essentially, it is the thickness of the slot the saw makes. While it seems like a fixed standard, the choice between thin kerf and full kerf has massive implications for your power tool's performance.
Full Kerf (Standard)
Standard full kerf blades usually remove about 3mm (1/8 inch) of material.
- Stability: The thicker steel plate makes the blade incredibly stable. It resists wobbling, vibrating, or deflecting when it hits a knot or hard grain pattern.
- Durability: The extra metal acts as a heat sink, helping the blade stay cooler during heavy-duty cutting.
- Power Requirement: This is the catch. Removing more wood requires more horsepower. Full kerf blades are best suited for powerful corded saws (15 amps or higher) or stationary table saws.
Thin Kerf
Thin kerf blades remove significantly less material, often around 2mm or less.
- Efficiency: Because you are turning less wood into sawdust, the saw's motor doesn't have to work as hard. This is the secret weapon for cordless circular saws. A thin kerf circular saw blade puts less strain on the battery, giving you more cuts per charge.
- Yield: When working with expensive exotic hardwoods, a thin kerf blade wastes less valuable timber.
- Stability Issues: The downside is that the thinner plate can be prone to flutter or deflection if pushed too hard. However, modern tensioning technology has largely mitigated this issue in high-quality blades.
Matching the Blade to the Material
Now that we understand the variables, how do we apply this to real-world materials?
1. Hardwoods (Oak, Maple, Walnut)
- Ripping: Use a 24T thin kerf blade. Hardwoods are dense; a thin kerf reduces resistance, preventing the saw from bogging down.
- Crosscutting: A 60T blade is the sweet spot. It provides a polish-ready finish without burning the dense grain.
2. Softwoods (Pine, Spruce, Fir)
- Construction: A standard 24T ripping blade is perfect. Speed is usually the priority here.
- Finish Carpentry: A 40T to 60T blade works well for trim. Softwoods are prone to tear-out, so a sharp, higher tooth count helps keep edges crisp.
3. Plywood and Sheet Goods
Plywood is tricky because the thin veneer on the surface splinters easily.
- Recommendation: You need a high tooth count (60T to 80T). Look for a specific tooth geometry called "Hi-ATB" (High Alternate Top Bevel), which slices the veneer fibres cleanly rather than punching through them.
4. Laminates and Melamine
These are the ultimate test. The brittle plastic coating chips if you look at it wrong.
- Recommendation: Use a dedicated laminate blade with a very high tooth count (80T+) and a specialized "Triple Chip Grind" (TCG) tooth shape. This combines a trapezoidal tooth with a flat tooth to gently remove material without shattering the brittle surface.
Why Professionals Choose Key Blades and Fixings
Understanding tooth count and kerf is useless if the manufacturing quality isn't there. A cheap 80-tooth blade will perform worse than a quality 40-tooth blade. This is why professionals rely on Key Blades and Fixings.
We curate our inventory based on performance, not just specs. When you buy a circular saw blade from us, you aren't just buying a piece of metal; you are buying precision engineering.
- Optimised Geometry: Our blades feature calculated hook angles and tooth grinds that maximise the effectiveness of their tooth count.
- Plate Stability: We stock blades with laser-cut expansion slots that allow the plate to expand as it heats up, keeping the kerf consistent and preventing warping.
- Carbide Quality: The "grain" of the carbide matters. We supply blades with micro-grain carbide tips that hold a sharp edge longer, ensuring that your 60T finishing blade stays a finishing blade for longer.
Conclusion
The "best" blade doesn't exist in a vacuum. The best blade is the one that matches your specific task. A 24-tooth ripping blade is a disaster for cutting melamine, and an 80-tooth finishing blade will burn out your motor if you try to rip oak beams with it.
By understanding the relationship between tooth count, kerf, and material, you can make informed choices that speed up your workflow, extend the life of your power tools, and improve the quality of your work.
Stop fighting your saw. Analyse your next project, check your blade specs, and if you need the perfect tool for the job, explore the professional range at Key Blades and Fixings.