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Table saw motor

Discussion in 'Do It Yourself (Not Computer-Related)' started by jaguar88xj6, Apr 27, 2010.

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  1. jaguar88xj6

    jaguar88xj6 Thread Starter

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    I have an old(70"s or 80"s) craftsman table saw(it was given to me and told it ran fine).Heavy cast iron top, direct drive 11.5 amp. The motor won't start on it's own. It hums and sometimes tries to turn left and sometimes right. If I spin the blade it will run slowly and get hot. If I get it spinning enough it will pick up speed and finally kick into high speed. Once there it runs good and cuts fine. It is not a capcitor start. The switch box has a switch and a relay inside. The relay has 3 terminals. 1 on the bottom and 2 on the top. The motor has 3 wires. 1 black,1 white and 1 red. It is wired,black from power cord to the switch, black jumper from switch to single connector on relay, white directly to white from motor, black and red from motor to the 2 other relay termials. The relay shuts the saw down if tipped. The rotor has no exposed windings. It looks like a smooth barrel. I can find any switches inside the motor. Motor seems to have 2 different windings inside. I'm running this saw in a detached garage with 14 guage wire running to the plug. It is not a dedicated circuit. Although my belt drive capacitor start saw runs perfect on the same plug. Any help will be appreciated. Thanks.
     
  2. JohnWill

    JohnWill Retired Moderator

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    Sounds like a capacitor start motor, are you SURE it's not a capacitor start?

    What's the exact model of the saw?
     
  3. jaguar88xj6

    jaguar88xj6 Thread Starter

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    That was my first thought also, but there is no capacitor, or any mounting screw holes on the motor and the power cord and motor cord go directly into the switch box and there is no room there for a cap either. I tried using a cap inline with the blackwire and it made no difference, just blew the cap after turning slowly. I'm at a loss. The saw is a Craftsman model 113.226680. Thanks.
     
  4. wacor

    wacor Banned

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    Bad brushes???

    Bad centrifugal switch??
     
  5. JohnWill

    JohnWill Retired Moderator

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    I can't believe this is a 100% induction motor, not to drive a saw! There has to be either a cap or at least the centrifugal switch mentioned by wacor.
     
  6. jaguar88xj6

    jaguar88xj6 Thread Starter

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    When I was given this saw it had a replacement motor(same as the original) and the original that burned up. They both have all the wiring and switch all originally conected. Hard wired to motor, pluged into relay in switch box. Power cord plugged into switch in switch box. You may be right, but I took the old motor and switch box apart and can find no cap. I don't know what a centrificul switch should look like, but don't see anything in the motor that looks like it could be one. What should I be looking for? Thanks.
     
  7. jaguar88xj6

    jaguar88xj6 Thread Starter

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    Sorry. I forgot to mention that this motor also has no brushes. Thanks again.
     
  8. Mumbodog

    Mumbodog

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    If there is no capacitor, then it has a centrifugal switch on the shaft inside the motor, it is stuck in the run position, most of the time you can clean and lightly lubricate it to return it to working order.

    .
     
  9. JohnWill

    JohnWill Retired Moderator

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    Yep, the centrifugal clearly has to rotate, so it's on the armature somewhere. :)
     
  10. Mumbodog

    Mumbodog

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    Its fixed to the armature (usually at the back end of the motor), it rotates with the armature, it has springs that keep it on the start windings of the field, when the armature reaches a certain RPM the centrifugal forces overcome the springs and switch current to the run windings of the field. This mechanism can get dirty and stick in the open position, and the motor cannot start on the run windings. Clean it and it should close and work normally. In extreme cases the centrifugal switch will need replaced, any motor rewinding shop will have them, and if they are nice, will sell you one at a reasonable price, otherwise replace the motor, Harbor Freight has reasonably priced replacement motors for table saws.

    .
     
  11. jaguar88xj6

    jaguar88xj6 Thread Starter

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    Thank you all. Will look for the switch and see if I can free it up.
     
  12. Koot

    Koot

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  13. K7M

    K7M

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  14. wacor

    wacor Banned

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    If there is a relay would there not be a capacitor though??

    The motors I work on that are capacitor start have a relay to take the start winding out of play.

    I am not familiar with the centrifugal switch other than remembering some of the older motors having them. If there was a cent. switch would there not be a need for a relay?
     
  15. paisanol69

    paisanol69

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    ...Not poking fun at you Koot, But at the Sears link you posted, it's obvious that whoever Sears hired for their data entry update work , for their online parts dept, definately did NOT HAVE A CLUE !!:D

    I guess since the main item is a table saw, whoever did the data entry figures that these "minature blades"were for the hobbist that deals in smaller jobs!!!

    And when you click on K7M's link, there a socket from what looks like a 3/8" drive set, listed as a "nut" ! Jeesh, I would hate to have to depend on Sears online repair catalogue, fo parts!!:mad:
     

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