How Do Table Saws Detect Fingers And Stops Immediately?

How Table Saw Detect Finger

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In all workshops, table saws are essential tools for cutting wood and cutting boards. If you are not familiar with how to use these tools correctly, they can be dangerous. There are often accidents where people have lost fingers or even their hands due to improper use of table saws.

For this reason, table saws include finger-detection technology to prevent accidents. By using this technology, the blade will not rotate when it contacts an object that shouldn’t be cut, such as someone’s finger.

What is the mechanism by which a Saw detects your finger? In this article, we will uncover the technology behind it, and by the end, you’ll find out that it’s more complex than it seems.

How Do Table Saws Detect Fingers (Complete Operation)

It is now safer to use table saws with the latest SawStop technology. AIM Safety technology stands for Active Injury Mitigation, which helps table saws detect fingers. The blade stops instantly as soon as your fingertips contact a blade with this technology.

Table saws without SawStop’s AIM can’t detect fingers, and you cannot install it on any other table saw. If you do, installing a SawStop on that table saw will require more structural modifications than buying a new SawStop.

Let’s discuss in detail how AIM technology detects the finger. And also, we will discuss other mechanisms used in table saws.

Digital Signal Processors

In SawStop saws, the blade gets electrical signals when the power is turned on. Despite not having a motor running, it does this.

Brake cartridges contain digital signal processors (DSPs) that monitor the signal for any changes. It monitors the signal through the gap between the blade and the brake and performs the following actions.

  • Detection

A digital signal processor monitors signal based on the fact that the human body is an electrical conductor. A small electrical signal travels from the blade to the human body without harming it. Your skin changes the current signal when it comes into contact with the blade and immediately activates the safety system.

  • Stoping

The aluminum brake blocks the blade within milliseconds. It causes a complete stop of the blade follows, and the motor loses power immediately. And this complete work SawStop saw can perform any one of three modes of mode stopping.

Standby Mode: In this mode, the power stays on, but the blades don’t turn.

Bypass Mode: This mode will not fire the brake even if the motor and blades are spinning. If the brake has fired, you can tell by the status light.

Normal Operation Mode: During regular operation, both motor and blades keep spinning, and the brake will fire if the DSP determines it is necessary.

There is also a submode for bypassing and a normal operating mode known as spinning down. This mode turns off the motor and slows down the blade, but it continues to run. Until the blade stops rotating, the green indicator light remains on.

  • Drop

Angular momentum propels the blade down the table after the blade stops, reducing the chances of subsequent contact several times faster than the blink of an eye. That means it happens in less than about 5 milliseconds.

  • Reset

Well done! Now you reset your saw, so you only need 90 seconds, and start cutting wood again because your finger survived the accident.

Blade Guards

Adding blade guards to a table saw is another way to ensure safety. It is possible to have passive or active guards. A physical barrier prevents fingers or other body parts from getting too close to blades when using passive blade guards.

An active blade guard that is electronic uses sensors to detect when something is too close to the blade. Active blade guards move automatically to cover exposed blade portions in these situations.

Other Technologies

There have also been several other technologies developed to increase the safety of table saws besides the technologies mentioned above. One of these is “brake technology.” Using sensors, it detects the blade’s proximity and stops it automatically.

This provision can prevent injury but can also cause malfunctions if the saw isn’t functioning properly.


To make table saws safer, manufacturers have improved safety features. Safety accessories such as blade guards and sensors can improve the safety of table saws. 

However, it is essential to remember that a table saw is a dangerous tool. So, no matter how safe the technology is, there is always the possibility of injury if you are not careful.

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