Stepping into the world of power tools can be intimidating, especially when faced with a wall of Circular Saw Blades covered in technical jargon. Terms like "kerf," "gullet," and "negative hook angle" might sound like a foreign language, making it difficult to choose the right blade for your project. But understanding this terminology is the key to unlocking better, safer, and cleaner cuts.
This guide is designed to demystify the language of saw blades. We will break down the essential terms into simple, easy-to-understand definitions, explaining how each feature affects the blade's performance. By the end, you will have the confidence to select the perfect Circular Saw Blade for any task, just like a seasoned professional.
The Anatomy of a Saw Blade: Key Terms Defined
Every part of a saw blade has a specific name and purpose. Let’s break down the most important terms you will encounter.
1. Kerf
What it is: The kerf is the width of the slot that the blade cuts into the material. Essentially, it is the thickness of the cutting edge.
Why it matters:
- Standard Kerf (thicker): Offers more stability, is less likely to bend or warp under pressure, and is ideal for powerful, corded saws cutting thick hardwoods.
- Thin Kerf (thinner): Removes less material, which puts less strain on the motor. This makes it perfect for cordless saws, as it extends battery life and makes cutting feel easier.
2. Gullet
What it is: The gullet is the curved space or valley in front of each tooth.
Why it matters: The gullet’s primary job is chip removal. As the tooth cuts, the waste material (sawdust) is collected in the gullet and ejected as the blade spins.
- Large Gullets: Found on ripping blades with few teeth. They can clear large amounts of sawdust quickly, preventing the blade from clogging and overheating during fast, aggressive cuts.
- Small Gullets: Found on fine-finish blades with many teeth. They are designed for slower, more delicate cuts where less material is being removed with each pass.
3. Hook Angle (or Rake Angle)
What it is: The hook angle describes the direction the tooth leans in relation to the centre of the blade. Imagine drawing a line from the centre of the blade to the tip of a tooth—the hook angle is the angle of the tooth's face relative to that line.
Why it matters: It determines how aggressively the blade cuts.
- Positive Hook Angle (e.g., +10° to +20°): The teeth lean forward, actively pulling the material into the blade. This is great for fast ripping in wood but can be too aggressive for other materials.
- Negative Hook Angle (e.g., -5°): The teeth lean slightly backwards. This creates a much less aggressive, scraping action. It is a critical safety feature for mitre saws (to prevent climbing) and for cutting hard, slick materials like metal and plastics.
4. Plate
What it is: The plate is the main steel body of the Circular Saw Blade, excluding the teeth.
Why it matters: The quality of the plate determines the blade's stability. A high-quality plate is made from tensioned, hardened steel that resists warping when it heats up. Premium blades often have laser-cut expansion slots in the plate to help manage heat and dampen vibration.
5. Bore
What it is: The bore is the hole in the centre of the blade.
Why it matters: The bore must match the size of your saw’s arbor (the spindle the blade mounts onto) perfectly. A mismatched bore is a major safety hazard. Common UK bore sizes are 20mm for handheld saws and 30mm for table and mitre saws.
6. Tooth Geometry
What it is: This refers to the specific shape ground onto the top of the carbide teeth.
Why it matters: The geometry dictates what the blade is designed to cut. The most common types are:
- ATB (Alternate Top Bevel): Teeth are bevelled in alternating left and right directions, creating a sharp, knife-like edge. This is perfect for clean crosscuts in wood and plywood.
- TCG (Triple Chip Grind): Alternates between a flat "raker" tooth and a chamfered "trapper" tooth. This durable, chipping action is ideal for tough materials like laminates, non-ferrous metals, and plastics.
- FTG (Flat Top Grind): Every tooth is flat. It’s an aggressive, chisel-like grind used for fast ripping along the grain of the wood.
Illustrated Glossary of Blade Terms
To help visualise these concepts, here is a quick summary:
- Plate: The main circular body.
- Bore: The central mounting hole.
- Teeth: The carbide cutting edges.
- Gullet: The valley between the teeth.
- Kerf: The width of the cut.
- Hook Angle: The forward or backward lean of the teeth.
(Visual aid: Imagine a diagram of a saw blade with arrows pointing to each of these parts, clearly labelling them.)
Quick Selection Guide for DIY Users
Feeling overwhelmed? Don't be. For most common DIY tasks, you can simplify your choice by thinking about the job you need to do.
I am building a garden shed or cutting framing timber...
- Your Goal: Speed and efficiency.
- What to Look For: A ripping blade with a low tooth count (18-24T) and an FTG (Flat Top Grind). The large gullets will clear sawdust quickly, and the aggressive teeth will power through the wood.
I am building bookshelves from plywood or fitting skirting boards...
- Your Goal: A clean, splinter-free finish.
- What to Look For: A fine-finish or crosscut blade with a high tooth count (40-60T+) and an ATB (Alternate Top Bevel) geometry. The knife-like teeth will sever the wood fibres cleanly.
I am fitting a laminate kitchen worktop or flooring...
- Your Goal: To cut without chipping the brittle top layer.
- What to Look For: A blade with a TCG (Triple Chip Grind) geometry. A high tooth count (48T+) is also beneficial. This will chip away at the laminate cleanly instead of shattering it.
I am using a cordless circular saw for a bit of everything...
- Your Goal: To maximise battery life and cutting power.
- What to Look For: A thin-kerf Circular Saw Blade. The thinner blade removes less material, putting less strain on your saw’s motor. A general-purpose ATB blade with around 40 teeth is a great all-rounder.
By learning this basic terminology, you are no longer just guessing. You are making an informed decision that will lead to better results, longer tool life, and a safer workshop. The right knowledge turns a simple steel disc into a precision instrument, and the right Circular Saw Blade will transform the quality of your work.