How Do You Know When to Replace Circular Saw Blades?

Has your circular saw been struggling to cut lately? Here's how to tell when your saw blade is dull and what you can do if it is.

Circular saws are an essential tool for professional tradesmen and serious DIYers alike. Depending on the blade, you can use a circular saw to cut through wood, metal and even concrete. However, a dull blade can dramatically hinder the quality of your saw cuts. Read on to learn how to tell if your circular saw blade is dull, and what you should do if it is.

What Are the Different Types of Circular Saw Blades?

Although a circular saw can cut through a wide range of material, it can only do so with the right type of blade. There are three primary types of circular saw blades:

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  1. Carbide-tipped. These are the most common type of circular saw blades, consisting of a steel disc with carbide-tipped cutting teeth around the outside edge. These blades are typically used for cutting through wood, but specially designed carbide blades can also cut through light-gauge metal. Carbide-tipped blades usually cost between $20 and $100 and can last from six months to a couple of years. The cost and longevity of carbide-tipped blades largely depend on the tooth count and the material they’re used to cut.
  2. Steel-tipped. Although somewhat rare today, steel-tipped blades are made entirely of steel and were the most common variety of circular saw blades before carbide-tipped options. Steel-tipped blades are usually cheaper than carbide-tipped, costing between $10 and $30, and are easier to sharpen than carbide-tipped blades. However, they aren’t nearly as durable and only stay sharp for about one-tenth as long as carbide.
  3. Diamond-edged blades. Diamond blades are made for cutting through masonry materials like concrete, brick and tile. The perimeter of the blade is coated in diamonds, and are usually completely round without cutting teeth. Diamond blades usually cost between $15 and $75. They can last between 12 and 120 hours of continuous use, depending on the quality of the blade and material they’re used to cut.

How Do I Know When a Circular Saw Blade is Dull?

Every circular saw blade wears out over time. There are several tell-tale signs that your blade is dull or is getting there. Signs that a carbide-tipped or steel-tipped blade are getting dull include:

  • The blade will cut slower than usual or may completely bind mid-cut;
  • The blade will create more tears or chipping than usual;
  • The blade will produce burn marks on the wood and may start smoking.

Signs that a diamond-edged blade is getting dull include:

  • The blade will glaze over, indicating the metal bond that holds the diamonds on the blade has melted over the diamonds;
  • The blade will look smooth, which indicates the diamonds have completely worn away;
  • The blade will cut slower than usual or completely bind mid-cut, just like carbide and steel blades.

Ignoring these signs can result in reduced cut quality and permanent damage to the blade.

What Should I Do If My Circular Saw Blade Is Dull?

Depending on the type of blade you’re using, you can clean, sharpen or replace it. More often than not, a dull carbide-tipped or steel-tipped blade is just dirty and needs to be cleaned. Simple remove it, soak it in an all-purpose cleaner and brush it clean. If you’re still experiencing symptoms after cleaning and reinstalling the blade, you may want to consider sharpening it.

Steel-tipped blades are the easiest to sharpen, and you can usually do so yourself with a hand file or mechanical blade sharpener.

Carbide-tipped blades are more difficult to sharpen because the teeth need to be ground at specific angles with a diamond wheel, so it’s generally recommended to have them professionally done. A professional sharpening usually costs between 25 and 50 cents per tooth, so you should weigh the cost of having it sharpened against the cost of purchasing a replacement.

Diamond-edged blades that are used on table-mounted miter or tile saws can be easily sharpened and deglazed with a dressing stone, but blades used on handheld circular saws typically need to be replaced.

James Fitzgerald
James Fitzgerald is a handyman and freelance home-improvement writer with a passion for DIY, gardening, and anything involving working with his hands. He has over a decade of professional experience in a variety of trades, including construction, tree work, landscaping, and general maintenance. When not in search of the next enticing DIY project, he may be cooking, lifting weights, riding his motorcycle, hiking out at the coast, or nose deep in a great book.