How Does A Circular Saw's Electric Brake Work News & Opinion

How Does a Saw’s Electric Brake Work


Tool manufacturers continue to add more safety and fatigue-reducing features on their products. Examples abound with auto lock-ons, auto lock-offs, blade guards, and shields—just to start. You may take one safety feature for granted simply because you can’t see it—an electric brake. On the best circular saws and many other saws, an electric brake marks a premium feature. This solitary feature has saved many a blade, wood floor, cord, or even a finger or toe! It’s easy for a scrap of wood or some obstruction to prevent the blade guard from falling back in place after a cut. Without an electric brake, Ryobi estimates that a blade can continue to spin for 12 seconds on some saws. An electric brake stops the blade in about 2 seconds. So how does a saw’s electric brake work to keep you safe?

Quick Summary

  • Trigger release reverses the electrical flow
  • This type of braking uses electricity
  • Mechanical brakes (more rare) stop a rotating wheel or blade nearly instantly
  • Electronic brakes wear out, but less-so than mechanical brakes
  • Efficiency and brake speed may slow over time—requiring service

Editor’s Note: This article was updated on October 8, 2018.

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How Does a Saw’s Electric Brake Work?

The electric brake might be technically difficult to accomplish, but the mechanism is easy to explain. Real easy. You ready for it? Here it comes:

The flow of electricity reverses when the trigger is released.

Reversing the electrical flow throws the motor into reverse long enough to provide the friction needed to stop the rotating blade. As a result, the saw blade stops much more quickly than it otherwise would on its own. It’s easy to imagine the potential damage a blade spinning for 12 seconds after the cut could do—particularly with larger, heavier saws. Equal danger exists with both circular saws and angle grinders which can be set down while the blade still spins.

While some grinders have mechanical brakes that stop a rotating wheel or blade instantly, electric brakes (which make up a majority of these systems) rely on electricity to stop the blade.

Ridgid MS255SR Miter Saw Action 2 Web

Using saws that have an electric brake whenever possible alleviates this danger. If you’re the purchase decision maker for your company or even just buying a tool for your own use, an electric brake is one feature you should insist on.

Do They Last?

While electrical brakes don’t have the same wear as mechanical systems, they can wear out over time due to brushes and other factors. In either case, it’s wise to monitor how long the blade spins after the trigger is released. If the brake ceases to stop the blade quickly, consider servicing or replacing the tool.

How Does A Saw's Electric Brake Work

Safety First

Don’t think of the electric brake as the first line of defense. The operator always serves that role. Staying safe on the jobsite starts with your mindset. As with any tool, it’s possible for this mechanism and/or the blade guard to fail, so the brake only serves as a backstop to careful use. The electric blade brake (or electronic brake) has likely been the invisible guardian of many tradesmen. Be sure it stays in working order.

 

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Now you know the answer when someone asks you, “How does a saw’s electric brake work?” We hope you work more safely because of it. If you’re a Pro and you have circular saw safety tips, add them in the comments below or leave a comment on Facebook, Instagram, or Twitter.

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Is there any way of know if the electric blade stop is malfunctioning? For example I am having a problem with my battery Makita circular saw that I have not been able to diagnose. It is not the brushes or the switch as I thought either of those could be the culprit and replaced them after reading over about them. Here is my problem. My saw acts like it wants to go but doesn’t I took apart the whole thing and it spins fine by hand so it seems that nothing is jammed in there. If you put your ear… Read more »