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Table Saw RPM to high

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  • Table Saw RPM to high

    I have a Ridgid R4510. While cutting the rpms shot up enough to blow the breaker. I reset the breaker and tried the saw again. It blew the breaker. I then tried it in a 20amp outlet and it ran but definitely higher than normal. It also smelled. The saw doesn't get much use. Do think the motor is bad? What else could it be? Thanks in advance for your feedback.
    Last edited by Monticapuletti; 08-02-2018, 01:13 PM. Reason: Grammar

  • #2
    the motor or capacitor is bad. probably the motor.
    ~~

    ... it was plumbed by Ray Charles and his helper Stevie Wonder

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    • #3
      The RPMs don't cause the breaker to trip, drawing too much current does.
      When you use the 20a circuit the motor isn't running higher than normal, its was just running lower than normal on the 15a circuit.
      The 15a ckt couldn't deliver the energy necessary so it ran the motor under voltage which cooked your motor to some extent.
      Always use the higher rated ckt (20a) and if you need an extension cord, use a heavy duty one.

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      • Mightyservant
        Mightyservant commented
        Editing a comment
        Welcome back Johncameron we havent seen you around much and I'm glad to see you back !
        Last edited by Mightyservant; 08-08-2018, 09:48 AM.

    • #4
      Obviously you have a problem. I would recommend you don't continue running the motor without identifying and fixing the problem as it could result in unnecessarily burning up the motor.

      Is this a direct drive table saw or belt drive?

      Regardless, with power disconnected, does the motor shaft turn freely? If it is direct drive, with power disconnected to the saw, does the blade turn freely and take a second or two to spin down? If it belt drive, disconnect the power and the drive belt and try spinning the motor shaft by hand. Does it spin freely?

      If the motor doesn't spin freely, I would recommend trying to replace the bearings which typically can be cross-referenced at a local bearing shop by showing them the old bearings.

      If the the motor turns freely, it might be worth removing the motor and taking it for analysis to a local motor shop.
      Last edited by JonWally; 08-11-2018, 03:31 PM.

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      • #5
        If the motor truly is spinning faster than it should that creates a safety issue (during use) other than damage to the motor, and that is the rim speed of the blade may be higher than it is rated for and you could end up with carbide teeth separating from the blade which would then be flying around the shop looking for a place to land, most likely in your eye !!

        So don't run that motor until you figure out what's wrong and fix it.

        On the 15A breaker, I'm not following your comments John. If the 15A breaker is undersized it would trip, it would not limit the energy (watts) delivered to the motor. The motor will draw what it wants be it normal or not, and the breaker will open if the trip current is exceeded, it will not throttle or limit power to the motor or create an undervolt condition. If a 15A breaker is the recommended size IAW the manual then operating with a 20A breaker just invites damage to the motor as the 20A breaker may not protect the motor from an overcurrent condition as intended.

        What am I not understanding about what you said John? Or are we saying the same thing in different ways.

        "When you use the 20a circuit the motor isn't running higher than normal, its was just running lower than normal on the 15a circuit.
        The 15a ckt couldn't deliver the energy necessary so it ran the motor under voltage which cooked your motor to some extent."
        "It's a table saw, do you know where your fingers are?" Bob D. 2006

        https://www.youtube.com/user/PowerToolInstitute

        ----

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        • #6
          Originally posted by Bob D. View Post
          I'm not following your comments John. If the 15A breaker is undersized it would trip, it would not limit the energy (watts) delivered to the motor. The motor will draw what it wants be it normal or not, and the breaker will open if the trip current is exceeded, it will not throttle or limit power to the motor or create an undervolt condition. If a 15A breaker is the recommended size IAW the manual then operating with a 20A breaker just invites damage to the motor as the 20A breaker may not protect the motor from an overcurrent condition as intended.

          What am I not understanding about what you said John? Or are we saying the same thing in different ways.

          "When you use the 20a circuit the motor isn't running higher than normal, its was just running lower than normal on the 15a circuit.
          The 15a ckt couldn't deliver the energy necessary so it ran the motor under voltage which cooked your motor to some extent."
          Yes, it should trip if its drawing too much current but breakers are not a fast acting device especially when current is right on the threshold. A 15 amp breaker may need to see 20 amp spike before it actually trips.
          Breakers work by either a magnetic coil pulling a spring loaded lever, or a bimetal actuator that moves when it gets too hot.
          Conversely, if a 80% rated 15a circuit breaker only loaded to 13 amps, it will eventually trip the breaker after about 3 hours when the heat inside the breaker reaches its threshold inspite of the fact current hasn't reached 15 amps.

          If you overload a circuit, the load (motor in this case) will always try to draw as much current as it can but the circuit (wire too small/high resistance) is incapable of doing so.
          When the current is unavailable, the voltage will drop. So the 120v motor runs slowly at about 90v and cooks.

          So yes, an overload circuit will limit the voltage once the max amperage of a circuit is reached and its not a good thing. It doesn't throttle it but a 15 amp circuit is only capable of delivering so much energy (1800va)

          It always best to use a circuit with a rating that exceed what you need.
          Such as putting a 15 amp load on a 20 amp circuit.

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          • #7
            Originally posted by Mightyservant View Post
            Welcome back johncameron we havent seen you around much and I'm glad to see you back!
            Thanks for the warm welcome Mightyservant.
            Always a pleasure seeing your posts.






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