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Thread: Table saw knee activated shut off lever

  1. #1
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    Table saw knee activated shut off lever

    There have been a few times that I wish this was on my saw so I built a prototype. The block that touches the switch is angled for square contact. The lever flexes to activate the switch exactly the correct way each time. If it were to break it will fall off leaving the stop switch exposed. Foot won’t accidentally activate unless I raise my foot at least 6 inches. It’s also not in the way when standing by it due to table and rail overhang.
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    Last edited by Bruce King; 11-08-2020 at 9:21 AM.

  2. #2
    Good idea. I built one for mine a few years ago and it's been a good add.
    "All that is necessary for the triumph of evil is that good men do nothing."

    “If you want to know what a man's like, take a good look at how he treats his inferiors, not his equals.”

  3. #3
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    My Delta Unisaw is built with one and it's a mixed bag for me. It can be very convenient and useful but sometimes I accidentally shut it down as well.
    I think that's the hard part with any design like this is to make it easy to shut it down but not to shut it down when not intended. I guess that's the fine line between for any such design as this. Even with what I design as a professional engineer this same issue is true. The resolution of this clearly involves looking at some not so typical methods.

  4. #4
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    Mine hangs from the fence rail from a hinge.

    DRO on Saw Stop (7).jpg

    A tap with the knee or the toe kills the power.
    "A hen is only an egg's way of making another egg".


    – Samuel Butler

  5. #5
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    My jointer has a brake with a short throw handle I have to be really careful not to bump it. It also opens the contacts that turn off the saw. I wouldn’t want anything like that on my tablesaw to easy to bump in to.
    Aj

  6. #6
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    It is great to be able to shut off the saw without taking any hands off the workpiece, or taking your eye off the blade.

  7. #7
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    Only possible problem with the first design is it may be too low and a foot could turn it off too easy. That may also be considered an advantage. i have considered adding a rope switch for the off control. My lathe came with a foot brake that also switches an off switch when stepped on. Some times I have to lift it up with my toe to get things moving. It has never fallen and engaged the stop switch or the brake by itself when things are running. It is the red bar in the photo. The photo is a little off because it is sitting up on a pallet. They are common on metal working lathes that can have hundreds of pounds of metal spinning at high rpm's
    Bill D
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    Last edited by Bill Dufour; 11-08-2020 at 12:23 AM.

  8. #8
    I made similar lever actuators for two saws, hinged from above and worked by knee or foot. A compression. spring ensured that a solid push was required to work it Never had a problem with accidental stops. When you need to shut the saw off but both hands are occupied, nothing else will do. The only better system I have used was the hydraulic blade raise mechanism on a Martin T72- you could dump the blade below the table with your foot faster than the e-stop would stop it.

  9. #9
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    I made this one for my table saw ...





    While it reaches as far as my knee, it is also easier to find and press with a hand than to find and press a small button.

    If you have the ideal design switch, this is the lever ...



    Regards from Perth

    Derek

  10. #10
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    Here's a slightly different way to do it. The stop control is that wood strip at the floor. It is hinged along the top edge. Tapping it with a toe stops the saw. The start control is the push button beside the orange push stick. The saw is powered through a power contactor relay which is inside the box with the pushbutton. A momentary-contact switch on the pushbutton closes the relay, and a momentary-contact switch at that that wood strip at the floor turns off the relay. I can easily find the turn-off switch with my toe no matter where I'm standing to operate the saw.

    tablesaw2.jpg

  11. #11
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    That’s the way to do it if your magnetic switch has gone bad and you don’t want to buy a new one. Hope it stays off if a half second or more power glitch occurs like a magnetic switch does.

  12. #12
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    Here's one I did when I had my Unisaw. I've since downsized and have a DeWalt portable saw and am trying to figure out how to make one for it. They are really useful.

    Stop.jpg
    Dick Mahany.

  13. #13
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    Cool, what were you using the extension jig for?

  14. #14
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    Quote Originally Posted by Bruce King View Post
    That’s the way to do it if your magnetic switch has gone bad and you don’t want to buy a new one. Hope it stays off if a half second or more power glitch occurs like a magnetic switch does.
    The saw didn’t have a magnetic switch , just a mechanical one. The power contactor cost me something like $10.

  15. #15
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    Quote Originally Posted by Eric Arnsdorff View Post
    My Delta Unisaw is built with one and it's a mixed bag for me. It can be very convenient and useful but sometimes I accidentally shut it down as well.
    I think that's the hard part with any design like this is to make it easy to shut it down but not to shut it down when not intended. I guess that's the fine line between for any such design as this. Even with what I design as a professional engineer this same issue is true. The resolution of this clearly involves looking at some not so typical methods.
    Good point, as a fellow P.Eng, the additional consideration I always included in the analysis is: what is worse, accidental shutoffs or not being able to shutoff quickly in an emergency? As a later post suggested, the addition of a spring to prevent accidental shutoffs is a good idea.

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