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Thread: Big planer start up and coast down time?

  1. #1
    Join Date
    Sep 2016
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    Modesto, CA, USA
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    7,396

    Big planer start up and coast down time?

    I bought a Powermatic 18" planer with a three phase motor. I would like to know how long it should take to go from a dead stop until it is at full speed and also how long to coast down to a stop. I need this information to set the VFD acceleration time. I am guessing 3-5 seconds. I do not see a coast down function on the vfd so I have to input a deceleration time.
    I do know that a general rule of thumb is acceleration and deceleration should be 3 seconds or more when there is only moderate spinning inertia. Going any faster can strain gears and pulleys. Once that planner is up to speed there is a lot of metal spinning around.
    Bill D

  2. #2
    Join Date
    Nov 2009
    Location
    Peoria, IL
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    2,955
    3-5 seconds would be way too quick. I'd go at least 15-20.

  3. #3
    Join Date
    May 2013
    Location
    Northern Virginia
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    1,155
    Mine starts in about 3 seconds. Stopping may be 5-7. But you can set it to anything you want. I think I have 5 or 8 seconds on my jointer and a 25 second stop.

  4. #4
    Quote Originally Posted by Bill Dufour View Post
    I bought a Powermatic 18" planer with a three phase motor. I would like to know how long it should take to go from a dead stop until it is at full speed and also how long to coast down to a stop. I need this information to set the VFD acceleration time. I am guessing 3-5 seconds. I do not see a coast down function on the vfd so I have to input a deceleration time.
    I do know that a general rule of thumb is acceleration and deceleration should be 3 seconds or more when there is only moderate spinning inertia. Going any faster can strain gears and pulleys. Once that planner is up to speed there is a lot of metal spinning around.
    Bill D
    Most VFDs state the units of accel/decel rate as Hz/sec, and default on most units I've worked on is 1 (hz/sec), so 1 minute to start or stop. ...Out of the box.

    That said, obviously you can set to whatever you want. The faster the 'accel' rate, the more the in rush current, and the less you save on the light bill. Too slow, and you grow old waiting for it to hit claidheamh-mor-peel mode. For 'decel', I'm sure you've seen the threads about braking of overrunning loads. With a 18" head, you may need either external brake resistors, or keep the decel above 10-15secs? If you start throwing 'high temperature' or 'high DC bus voltage' faults every time you stop it, you'll know the decel rate is a bit aggressive.

    I have my 5hp DC set for 20sec accel, and 60sec decel (easy on the bill going up, and there is no safety risk coming down). For a planer, I'd try 10-12sec on both accel & decel to start. YMMV.

  5. #5
    Join Date
    Dec 2006
    Location
    Toronto Ontario
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    10,865
    I would set acceleration to 5 seconds and deceleration to 10 seconds.

    It’s a pretty small machine…..Regards, Rod.

  6. #6
    Join Date
    Dec 2005
    Location
    West Lafayette, IN
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    6,478
    It shouldn’t take too long to slow down, maybe 5 seconds. If you set it too short, say 3 seconds, no worries the VFD will hit overload and the cutterhead will coast to a stop after. Just add a second or two and try again.

  7. #7
    Join Date
    Sep 2016
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    Modesto, CA, USA
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    Further reading of the manual says parameter #6 options are "stop by itself" or "deceleration". I assume "stop by itself" is coast down with no braking. That avoids having to worry about deceleration rates and times. For a planer or jointer I do not think a spinning cutterhead is much of an issue. For a tablesaw, drillpress or shaper braking is a good idea with an exposed blade and kickback concerns.
    Bill D
    Last edited by Jim Becker; 05-21-2022 at 11:47 AM. Reason: language

  8. #8
    Join Date
    Apr 2017
    Location
    Michigan
    Posts
    2,257
    My table saw is set to 1 second accel and 1 second decel. Very handy and never had a problem. No external resistor.

  9. #9
    Join Date
    Sep 2016
    Location
    Modesto, CA, USA
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    7,396
    One second deceleration sounds risky to me. The arbor nut might unscrew at that torque load.
    Bill D

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