How Does SawStop Detect Fingers?

No matter how many times I watch the SawStop video demo using a hot dog to show how quickly the blade stops spinning when it comes in contact with the dog, it still amazes me.  The mark left on the hot dog is minimal, at worst, hardly a nick, and had it been a finger, it might not have shed any blood.

In an effort to make table saws safer, SawStop developed a system that somehow senses skin, or at least something soft, and immediately stops the spinning blade dead in its tracks the moment it comes in contact with skin.

Imagine that contact with skin, and the blade stops spinning.  That finger detection technology is like magic.

However, there is some science behind SawStop’s safety technology, and SawStop has protected its development of this technology with patents.  Just exactly how does that safety technology work, though?  It can’t be magic, can it?

We’ve written about SawStop, and their table saw safety features in the past, including SawStop and Festool, SawStop patents, and SawStop Professional vs Industrial table saws.

Who Is SawStop?

SawStop is owned by TTS Tooltechnic Systems AG & Co. KG, a privately held German company that also owns Festool. TTS Tooltechnic Systems acquired SawStop in July 2017 for an undisclosed amount.

SawStop was founded in 2000 by Dr. Steve Gass, who invented the company’s signature flesh-sensing technology. The technology uses a small electrical current to detect when skin contacts the saw blade. If skin is detected, the saw stops in milliseconds, preventing serious injury.

SawStop table saws are the #1 cabinet saw in North America.

What Is The SawStop Safety Technology?

SawStop safety technology is a patented system that uses a small electrical current to detect when skin contacts the saw blade. If skin is detected, the saw stops in milliseconds, preventing serious injury.

The SawStop safety system works like this:

1. The saw blade has a small electrical current running through it.
2. When skin contacts the blade, the current changes because the human body is conductive, meaning an electrical current will run through it easily.  We know this from accidental electrocutions where someone has come in contact with an electrical current (a frayed plug, or a downed power line, maybe).
3. The change in the electrical signal then activates the full safety system. You do not have to be grounded for this to activate, either; the simple change in electrical signals is enough to prompt activation.
4. When the blade has come to a complete stop, the blade is dropped inside the housing and below the surface of the tabletop so that no subsequent contact fan be made and no further harm can be caused.
5. The power to the motor is shut off.

The entire process happens in less than 5 milliseconds, which is much faster than a human can react. The SawStop safety technology is one of the most effective ways to prevent table saw injuries.

The blade and brake cartridge can then be replaced, taking less than 2 minutes, and the saw is ready for use again after you’ve stopped any bleeding and wrapped the finger, hand, or arm.  The brake cartridge includes aluminum brake springs that, if you will, spring into action when the system is triggered by contact with skin.

Of course, it does require that you keep a second blade and brake cartridge on hand in the event of such an injury. It might seem like a small price to pay for the safety system, though, a system that might save your finger(s).

Every SawStop comes with this sophisticated safety system, too, stopping the blade and dropping it into the cabinet housing in milliseconds.

As an interesting side note, the human brain calculates its knowledge in milliseconds, so just as you begin to realize you’ve been harmed, the blade has already stopped and dropped, and the motor is off.  Stopping a rapidly spinning blade within milliseconds is pretty darn impressive.

Since SawStop introduced its first table saw in 2004, the company has recorded over 6,000 “finger saves”. This means that SawStop has prevented over 6,000 serious table saw injuries.

The SawStop safety system is not perfect. It can be triggered by other materials that are conductive, such as metal or salt. However, the SawStop safety features are still very effective at preventing table saw injuries.

If you are looking for a table saw that is as safe as possible, a SawStop table saw is a great option. The SawStop safety system is a valuable investment that can help to protect you from serious injury.

Are Blade Guards Effective in Preventing Injury, too?

Yes, blade guards on table saws are effective in preventing injury. They help to protect the user from contact with the blade by physically blocking it. Blade guards can also help to prevent kickback, which is a serious hazard associated with table saws.

A study by the Consumer Product Safety Commission found that table saws with blade guards were associated with a 70% reduction in injuries. The study also found that table saws with riving knives, which are similar to blade guards, were associated with a 50% reduction in injuries.

It is important to note that blade guards are not foolproof. They can be removed or not used properly, and they can be ineffective in certain situations. However, they are an important safety feature that can help to reduce the risk of injury from table saws.

Here are some tips for using blade guards on table saws safely:

• Always use the blade guard when making cuts.
• Make sure the blade guard is properly adjusted and that it does not interfere with the cut.
• Never remove the blade guard unless it is absolutely necessary.
• Be aware of the limitations of the blade guard and take additional precautions when necessary.

If you are using a table saw, it is important to follow all safety precautions, including using a blade guard.  A riving knife is also an excellent safety feature that can help protect your face and head by greatly diminishing the chance for kickback.

By using these safety features together – the SawStop system, blade guard, or riving knife,  you can help to reduce the risk of serious injury.

Can You Bypass The SawStop Safety Feature?

Yes, you can bypass the SawStop safety feature. There is a setting called “bypass mode” that allows you to disable the safety system. Bypass mode is useful for cutting conductive materials, such as metal or carbon fiber, that would otherwise trigger the safety system.

To activate bypass mode, follow these steps:

1. Turn off the saw.
2. Locate the bypass switch or key. The switch is usually located on the top of the control panel, and the key is usually located on the side of the saw.
3. Press and hold the bypass switch or insert the key and turn it to the “on” position.
4. Turn on the saw.

The saw will now be in bypass mode, and the safety system will be disabled. Once you are finished cutting, be sure to turn off the saw and return the bypass switch or key to the “off” position.

It is important to note that bypass mode should only be used when necessary. The SawStop safety system is a valuable safety feature that can help to prevent serious injury. If you are not sure if you need to use bypass mode, it is best to err on the side of caution and leave the safety system enabled.

Here are some additional things to keep in mind about bypass mode:

• Bypass mode is not available on all SawStop saws.
• Bypass mode can only be used for a limited number of cuts. After a certain number of cuts, the safety system will automatically re-enable.
• Bypass mode does not affect the blade guard or riving knife. These safety features should always be used when operating a SawStop saw.

Why Would You Want To Bypass The SawStop Safety Feature?

There are a few reasons why you might want to bypass the SawStop safety feature:

• To cut conductive materials, such as metal, carbon fiber, or green/ wet wood, that would otherwise trigger the safety system.
• To test the safety system to make sure it is working properly.
• To make a specific cut that would be difficult or impossible with the safety system enabled.

This special temporary operation mode will allow the cutting of conductive materials other than the human body without activating the safety system. The braking system is disabled, and the saw blade will not be stopped or dropped.

It is far more than simply pushing a button, though, too – turning off a feature that could take a finger or two should not be made easy where even a slight carelessness could cost you skin and blood.

Video Demo on Real Skin

It’s short, it’s a real finger, and it’s magic.

A safer table was the goal, and SawStop achieved it with the safety system.   Over 6,000 fingers were saved, according to the SawStop website reviews.  That is most definitely a safer table.

Blade guards and riving knives also make a safer table.  Collectively, they give us every opportunity to be safe and keep all of our fingers intact when using our table saws.