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Thread: SawStop Injury

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    SawStop Injury

    This video is hopefully one of the worst injuries received with a SawStop. Don't watch if you're queasy.


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    Re: SawStop Injury

    A pair of Grr-ripper's would have prevented that particular accident as well.

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    Re: SawStop Injury

    He's really short.

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    Re: SawStop Injury

    all I see is a black rectangle in your post----------no play button, no link, etc. ?????
    We make a living by what we get...............We make a life by what we give

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    Re: SawStop Injury

    Quote Originally Posted by walnutjerry View Post
    all I see is a black rectangle in your post----------no play button, no link, etc. ?????
    Can't help you with that. Maybe Ethan has an idea. It's working for others, including me. Here's what we see:
    Attached Images Attached Images

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    Re: SawStop Injury

    I have the overarm blade guard and the dust collection it adds is very good. Recommended.
    I don't believe in Astrology. I'm a Sagittarius and we're skeptical.

    "May the grain be with you" - Roy Underhill

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    Re: SawStop Injury

    Obviously that injury could have been much worse. But my question is did that sawstop function correctly or did it fire slower than it should have. I have seen the demo many times but never seen the hot dog look like that. I wonder if sawstop owners can test their saws response time without destroying a brake and blade

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    Re: SawStop Injury

    Phil, as I recall, his saw is seven years old. I wonder if the newer ones are faster. I had the same question.

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    Re: SawStop Injury

    I would say that this mans being out $300 is a lot better deal than losing the whole thumb and potentially eliminating his ability to even do woodworking. Its pretty hard to grasp things without a thumb I would imagine.

    Just saying... he is a lucky man and I would say the SawStop saved him a lot more than what he lost in cash.

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    Re: SawStop Injury

    I've watched some demos with hotdogs and I suspect the guy in the video was moving his hand faster than the hot dogs are being moved into the blade. He describes moving material away form the blade and if he does it like I sometimes do it, he was flicking it away with a quick movement. I think how many teeth get you and how deep they get you are a function of how your hand is moving. More forceful movement towards the blade and quicker movement both mean more injury - even when the blade stops in the same time. I have no idea if SawStop has changed their cartridges over time. They are using something like gunpowder to trigger the blade dropping and the aluminum block jamming into the blade but there are different kinds of gunpowder that vary by burning rate - there is actually quite a large range. (something like a 25ACP needs a lot faster powder than a 375 H&H rifle).

    To me the lesson is that a SawStop is not a reason to adopt bad practices at the table saw. You still can get bit.

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    Re: SawStop Injury

    Quote Originally Posted by patlaw View Post
    Phil, as I recall, his saw is seven years old. I wonder if the newer ones are faster. I had the same question.
    I've wondered if the cartridges wear out over time, and if too old don't function as well or as fast. A lot of shops have wide variations in temp and humidity over the seasons.

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    Re: SawStop Injury

    I took a minute to google up how the sawstop cartridges work. They do not use a fast burning powder to activate, they use a spring. The spring is held in tension by a wire that melts when the aluminum block is slammed into the revolving blade. The wire melts when the electronics detect you touched the blade by a change in the current it is always placing on the blade.

    That leaves me a little curious about the spring design. A spring held in a compressed state for an extended period of time (possibly years) can take a set - can lose some of it's force. It looks like a pretty small spring and Wikipedia says it is applying 1000 lbs of force - doesn't seem credible for such a small spring. But if the material is at a high state of stress, it makes creep much more likely. If you got the spring really hot that would increase creep too but most of the cartridge is plastic so I doubt you could hurt the spring without destroying the plastic. The restraining wire is another potential aging issue. It also could creep and it's electrical properties could also change with age.

    So do SawStop cartridges get old and need replaced? Do they say anything about that?

    Wikipedia (which I realize is open access so not always reliable) says activation is supposed to be in no more than 5 milli seconds and the outside of the blade can move 10.4 inches (1/3 of a revolution) in that amount of time - enough to do the damage in the video if the thumb is moving firmly into the blade in my estimation. So it may have functioned normally. 1/3 of a revolution is right for a 5 millisecond time if the saw is 3600 rpm.

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    Re: SawStop Injury

    Gotta remember, besides stopping when the blade is touched, the reaction overcomes the clamping mechanism on the trunnion and the blade drops below the table. As the trunnion pivots downward, moving in an arc, the blade moves away from the operator. Also notice the blade in the video has “depth limiting” protrusions behind each tooth. Sawstop recommends Not to use this type blade as it can slow the reaction time of the safety mechanism.
    Last edited by riggsp; 07-11-2018 at 07:19 PM.

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    Re: SawStop Injury

    I always find it humorous when something goes wrong, or has potentially gone wrong, with a SawStop and all the SS owners have to step up and defend it.
    Happiness is a direction not a destination. ~Athena Orchard

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    Re: SawStop Injury

    I think that you have hit on the problem. The anti-kickback, blade depth limiting features of this blade would reduce the effectiveness of the Sawstop braking mechanism by keeping the blade from digging in to the brake as quickly as it would have done without the depth limiting features.

    Pete

    Quote Originally Posted by riggsp View Post
    Gotta remember, besides stopping when the blade is touched, the reaction overcomes the clamping mechanism on the trunnion and the blade drops below the table. As the trunnion pivots downward, moving in an arc, the blade moves away from the operator. Also notice the blade in the video has “depth limiting” protrusions behind each tooth. Sawstop recommends Not to use this type blade as it can slow the reaction time of the safety mechanism.
    Pete - KD4CQZ

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