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3/4HP Belt Sander Motor

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rsmith52

Joined: 16 Mar 2017
Posts: 15
Location: Crawford, CO

Posted: Mon Apr 13, 2020 11:51 am Post subject: 3/4HP Belt Sander Motor

Not directly aircraft related but a tool that I use extensively in construction of my Bearhawk for shaping metal parts. The motor is now spooling up very slowly and when a load is placed on it, slows down considerably. As far as I can tell, it is brushless, It's described as Type:  TEFC Capacitor-Start Induction and does have a large external capacitor. Any ideas on repairing instead of replacing this?

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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Apr 13, 2020 4:09 pm Post subject: 3/4HP Belt Sander Motor

At 02:46 PM 4/13/2020, you wrote:

  	  Quote: 	
		  Not directly aircraft related but a tool that I use extensively in construction of my Bearhawk for shaping metal parts. The motor is now spooling up very slowly and when a load is placed on it, slows down considerably. As far as I can tell, it is brushless, It's described as Type:  TEFC Capacitor-Start Induction and does have a large external capacitor. Any ideas on repairing instead of replacing this? 	




  Hmmm . . only one capacitor? If so, the capacitor

  is significant only for starting. If it spools up

  slowly -AND- lugs down under load, I'm thinking

  the motor has hurt windings . . . not good if

  this is the case.



  There is a centrifugal switch that disconnects

  the start winding and its companion capacitor

  after the motor reaches some fraction of

  nameplate rpm. If that switch is burned, then

  it wouldn't start at all. The fact that

  it is 'sluggish' at all times does not bode well.



 

   Bob . . .

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barp99(at)gmail.com
Guest

Posted: Mon Apr 13, 2020 5:00 pm Post subject: 3/4HP Belt Sander Motor

On 14/04/2020 10:05 am, Robert L.       Nuckolls, III wrote:

     

      	  Quote: 	
		                At 02:46 PM 4/13/2020, you wrote:

               	  Quote: 	
		  Not           directly aircraft related           but a tool that I use extensively in construction of my           Bearhawk for           shaping metal parts. The motor is now spooling up very slowly           and when a           load is placed on it, slows down considerably. As far as I can           tell, it           is brushless, It's described as Type:  TEFC Capacitor-Start           Induction and does have a large external capacitor. Any ideas           on           repairing instead of replacing this? 	
       

       

        Hmmm . . only one capacitor? If so, the capacitor

        is significant only for starting. If it spools up

        slowly -AND- lugs down under load, I'm thinking

        the motor has hurt windings . . . not good if

        this is the case.

       

        There is a centrifugal switch that disconnects

          the start winding and its companion capacitor

          after the motor reaches some fraction of

          nameplate rpm. If that switch is burned, then

          it wouldn't start at all. The fact that

          it is 'sluggish' at all times does not bode well.

         

                

             Bob . . .     	
     There is a small chance it is a capacitor run motor.       A capacitor run motor has no centrifugal switch, and the second       winding stays in circuit. If your capacitor starts to fail, its       capacitance will drop, reducing the phase angle between the two       magnetic fluxes, reducing start and run torque. If no centrifugal       switch, check the capacitor for correct capacitance, and replace       if low, this may be an easy and cheap fix.  

       

       Brian Phillips.

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stuart(at)stuarthutchison
Guest

Posted: Mon Apr 13, 2020 7:27 pm Post subject: 3/4HP Belt Sander Motor

I have a recurring problem with the start circuit on my heavy duty cold saw, but itâ€™s an easy fix.  

 I started by changing the capacitor, but it wasnâ€™t that.  Turns out that periodically I need to use a small file to clean the centrifugally-controlled points that keep the start capacitor in circuit until the motor spools up.  Otherwise it stays  slow, bogs down and starts making smoke after about 30 seconds.  I get a season or two out of it before cleaning again.

  

 Cheers, Stu

    	  Quote: 	
		   On 14 Apr 2020, at 10:53 am, Brian Phillips <barp99(at)gmail.com (barp99(at)gmail.com)> wrote:

     On 14/04/2020 10:05 am, Robert L. Nuckolls, III wrote: 

  	  Quote: 	
		   At 02:46 PM 4/13/2020, you wrote:   	  Quote: 	
		  Not directly aircraft related but a tool that I use extensively in construction of my Bearhawk for shaping metal parts. The motor is now spooling up very slowly and when a load is placed on  it, slows down considerably. As far as I can tell, it is brushless, It's described as Type:  TEFC Capacitor-Start Induction and does have a large external capacitor. Any ideas on repairing instead of replacing this? 	
    Hmmm . . only one capacitor? If so, the capacitor  is significant only for starting. If it spools up  slowly -AND- lugs down under load, I'm thinking  the motor has hurt windings . . . not good if  this is the case.   There is a centrifugal switch that disconnects  the start winding and its companion capacitor  after the motor reaches some fraction of  nameplate rpm. If that switch is burned, then  it wouldn't start at all. The fact that  it is 'sluggish' at all times does not bode well.   

  Bob . . . 	
 There is a small chance it is a capacitor run motor. A capacitor run motor has no centrifugal switch, and the second winding stays in circuit. If your capacitor starts to fail, its capacitance will drop, reducing the phase angle between  the two magnetic fluxes, reducing start and run torque. If no centrifugal switch, check the capacitor for correct capacitance, and replace if low, this may be an easy and cheap fix.    Brian Phillips.

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