Saw Stop, the saga

[usonian]

https://www.lumafield.com/article/new-vs-used-sawstop

Some folks took the time and money to reverse-engineer one.

Before SawStop shares its patent with the public, we thought we’d see how much of the brake’s engineering we could uncover with industrial X-ray CT. Using our Neptune scanner and Voyager software, we compared CT scans of a new and deployed brake to understand how the SawStop works and the hit it takes when one of them comes to the rescue.

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The SawStop safety brake represents a remarkable engineering feat in woodworking safety. It operates by running an electrical current through the saw blade, which is continuously monitored by the brake cartridge. When the blade comes into contact with skin, the electrical signal is disrupted, triggering the brake mechanism. In less than 5 milliseconds—faster than a car airbag—the actuator assembly unleashes the aluminum pawl and halts the blade spinning at 3,500 RPM. The saw blade teeth bite into it, and the blade’s momentum causes it to retract under the table to prevent further injury.

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The stark reality of table saw injuries has led the U.S. Consumer Product Safety Commission (CPSC) to consider mandating advanced safety features, such as the SawStop safety brake, on all new saws sold in the country.

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SawStop was founded in 1999 by Dr. Steve Gass, a patent attorney and physicist who invented the Active Injury Mitigation (AIM) system to halt a saw blade almost instantly upon contact with skin. Initially, Gass attempted to license the technology to major power tool companies, but none were interested. Now, opponents of the CPSC’s proposed law claim that implementing the technology would raise the price of table saws. Despite previous litigation against would-be imitators of their safety brake, SawStop has committed to dedicating its original patent to the public when these new regulations go into effect.

Vast amounts of detail at the link, including 3-d model in your browser.

Live long and continue to have 10 fingers.

One comment on Hacker News:
I recall reading that the majority of their patents were expiring in the next few years and the one that they’ve offered to not enforce (rather than release) is the important one that doesn’t expire until the 2030s.

More, if you’re interested.
https://news.ycombinator.com/item?id=42361825