When the sharpening cost is a large fraction of a new blade, when the carbide tips are already ground short, or when the body has been overheated. A blade with blued patches or a visible wobble is scrap whatever the teeth look like.
Resharpening is excellent value on a good blade and a waste of money on a cheap one. Three things decide which you have.
Carbide left on the tip
Each grind removes material from the tooth. A quality blade starts with tall tips and takes many grinds; a budget blade starts with a thin sliver brazed on and has one, maybe two, before the tooth is level with the body. Look at the tips side-on against a fresh blade of the same type. If they are visibly stubby, this is the last time.
The state of the body
The body is the part nobody inspects and the part that ends blades. A blade that has been overheated in a bind shows blue or straw discoloration around the gullets, and heat destroys the tensioning that keeps the plate flat and stiff at speed. That is permanent. No amount of tooth grinding fixes a body that has lost its tension.
Spin the blade on a nail through the bore and sight along it. Visible wobble is the end.
Missing or chipped teeth
A saw doctor can replace a tooth, at a price that only makes sense on a large or specialized blade.
What a sharpening service does
A carbide blade is ground on diamond wheels, usually on the top and the face of each tooth, which is why every grind shortens the tip a little. A good service also checks the plate for flatness and can replace a missing or broken tip; ask before you hand the blade over whether they do both, and what a replacement tip costs.
Related questions
How many grinds a blade can take is covered in how many times a saw blade can be resharpened, and what to expect from a service in can I get a saw blade resharpened.
The rule
If the blade cost less than about two sharpenings, replace it. If it cost several times a sharpening, sharpen it and keep sharpening it.
Last reviewed October 29, 2026