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Thread: How long does your table saw blade spin after power off?

  1. #1

    How long does your table saw blade spin after power off?

    Always had contractor table saws, but finally bit the bullet and upgraded to a Jet ProShop II. First thing I noticed was how long the blade spins after turning the saw off.

    Old rigid saw - blade stops in 8 seconds.

    New Jet table saw - 13 seconds! That additional 5 second s seems like an eternity.

    As the Jet is more powerful, I'm wondering if the longer spin is common for other 1.5+ hp table saws.

    Is 13 seconds reasonable for middle tier saws?

    Any inputs appreciated.

  2. #2
    Join Date
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    Mine spins for a few seconds, of course it has electronic blade braking to meet the EU 10 second rule with a dado stack on it..........Rod.

  3. #3
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    3 seconds for my Unisaw. That's what I told the VFD to do.

  4. #4
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    Sep 2018
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    PM 66 5hp 3 phase 3 seconds on the VFD.

  5. #5
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    1993 Unisaw, 3HP. Three times tried.........7, 8, and 8 seconds. 220V, single phase.

    Saw untouched original, using full kerf Freud rip blade.
    Rick Potter

    DIY journeyman,
    FWW wannabe.
    AKA Village Idiot.

  6. #6
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    I remember the big disk sander in high school woodshop took many minutes to coast down to a stop. I guess 24" diameter or so. probably a cast iron disk. No belts just direct drive so the motor just added more mass to spin down.
    Bil lD

  7. #7
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    My 3 HP SawStop takes about 3 seconds to wind down. Jack Forsberg has a video of a massive 36" direct drive disc sander that takes several minutes to coast down.

  8. #8
    My Baileigh 3HP, 220V, 1PH takes 9 seconds.

  9. #9
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    OK VFD guys... can you explain how the VFD ended up on the saw? FActory installed? What is the benefit of controlling the blade speed on a TS?
    the brake capability is really neat feature...
    my PM2k takes 10 seconds to stop...I stick a piece of pine in it... a manual brake

  10. #10
    Quote Originally Posted by Will Blick View Post
    OK VFD guys... can you explain how the VFD ended up on the saw? FActory installed? What is the benefit of controlling the blade speed on a TS?
    the brake capability is really neat feature...
    I assume they have 3 phase motors but single phase service. No real need to vary the speed in normal operation.


    My slider has a brake, although it's not on a VFD. The ~3s stop time is nice - long enough that you pause, not so long that you get impatient and do dumb things.

  11. #11
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    Dan, dumb things indeed!!
    I am very cautious ww. But its amazing how fast we can make a simple mistake.
    I would love a brake, but dont think there is any aftermarket ones, if so, pls advise.
    Once I made a bunch of cuts... I finished, turned off saw, stacked some of the wood to the left of the blade. I have a blade guard. I then grabbed the small sliver off cuts to the right of the blade, one offcut was stuck under the blade guard, I lifted it up and my finger hit the side of the spinning blade, not the teeth...the blade was at the end of the ramp down cycle but still spinning, but it was so long after I turned off the saw, I forgot it was still free wheelin... no damage to finger, but a few seconds earlier, and hit the teeth, could have lost a digit, its that simple, many ways to loose a digit. These blades are so sharp, ramp down speed can destroy a finger.
    I had headphones on, which stopped me from hearing, which might have helped. It made me think how beneficial a brake would be. I use a pine board when I need to stop the blade, for repetitive cuts where offcut needs to be removed.
    But that time, I had no reason to stop the blade, and it almost cost me!

  12. #12
    18" blade on a DD saw takes a bit, so does the SLR

  13. #13
    Join Date
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    Quote Originally Posted by Will Blick View Post
    OK VFD guys... can you explain how the VFD ended up on the saw? FActory installed? What is the benefit of controlling the blade speed on a TS?
    the brake capability is really neat feature...
    my PM2k takes 10 seconds to stop...I stick a piece of pine in it... a manual brake
    VFDs have many purposes (and functions) besides variable speed control.

    Many can convert from single phase input power to three phase output power, needed for many used machines with three phase motors from commercial shops.

    Three phase motors do not have torque ripple like single phase motors do, so some users prefer the smoother operation of three phase motors.

    Most VFDs are programmable for turn-on ramp up time (limiting starting torque and/or current if needed) for the motor to reach operating speed.

    Most VFDs are also programmable for stop time, either lengthening or shortening the normal coasting time to a stop. Most will perform some braking, and can be configured to dump excess energy to an external power resistor to stop the motor more quickly if desired.

    Three phase motors are more reliable that single phase motors, since there are not centrifugal start/run switches, start or run capacitors. However, the VFD itself includes capacitors, so the combination of VFD with three phase motor is likely no more reliable than a single phase motor.

    Andy

  14. #14
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    I think all the aftermarket dc injection brakes only work on three phase motors? Probably as cheap to buy a small VFD today since they are much more common so probably cheaper.
    Bill D

  15. #15
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    Quote Originally Posted by Bill Dufour View Post
    I think all the aftermarket dc injection brakes only work on three phase motors? Probably as cheap to buy a small VFD today since they are much more common so probably cheaper.
    Bill D
    My saw uses DC injection on a single phase motor....Rod

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