Risking your life with damaged circular saw blades.


Vern Burke, SwiftWater Edge Tool Works
Biddeford, ME

I’ve just been reading a report online about injuries to a serviceman in Iraq from the structural failure of a diamond circular saw blade. I’m going to talk a little in this post about the high risk from saw blade damage.

Circular saws are dangerous enough to deal with, having one come apart, spraying high speed shrapnel, is REALLY dangerous. Fortunately, it usually takes a lot to cause structural failure of a saw blade.

In this case, cracks that started in the expansion slots of the blade caused a section to break out and be thrown, injuring the operator.

The remaining sections of the blade show the cracking clearly on every single section.

The real problem here isn’t the cracking however. As this picture shows, the teeth and plate of this blade were severely eroded, probably from extreme amounts of abuse and operation well past the point the blade was worn out. This blade has worn the diamond coating off the teeth long ago and been cutting directly on the steel tooth, which the steel was never designed for.

Cracks from other sources such as overheating or hitting metal in wood are one thing. Cracks because you operate the blade far beyond any sensible life span and wear the whole structure of the blade thin is just silly. I’ve also seen this done with carbide table saw blades. I had a customer bring me in a 10″ carbide blade that he had knocked every single carbide off of and he was cutting directly on the steel teeth. DON’T DO IT!

Imagine this kind of failure happening with a 30″ cordwood saw blade or a sawmill type circular blade!

The takeaway from this is not only to inspect your circular saw blades (big and small) for general damage such as cracks but also to know when to call it a day on a worn out blade.

If the diamond material is all gone, if your blade is missing carbides, if the teeth have eroded and are not capable of being properly sharpened, it’s time to throw it out before it becomes a spinning hand grenade.

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