Reversing Drum Switch And Split Phase Start Cap Motor
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  1. #1

    Reversing Drum Switch And Split Phase Start Cap Motor

    The 1/2 H.P. 120 volt motor on my lathe finally kicked, it was only the start winding points that got fried, but the motor was so dirty and greasy, and it had overheating issues, so I got a new one.

    I looked at the old drum switch, and it was pretty ratty, so I got a new one. A friend gave me the motor, and I picked up the drum switch from Grainger for about sixty dollars with tax.

    The only problem was that I did not have a schematic for the motor and rather than guess and fry the start winding points I figured I would take it apart and I am glad I did. The main lug that I would normally attach the power in, was also tied to the start winding points. So I had to take the two leads off that fed the two-run windings and connect them directly to the neutral out from the drum switch. And then run one of the alternating/reversing, start winding leads out from the drum switch to the main lug on the motor. And then connect the start winding lead from the motor to the output of the start winding points. It worked perfectly. If you ever have to do one, this could save you from frying the points with a direct short. This drum switch only requires four wires from the switch to the motor but you should have a ground too.

    Sincerely,

    William McCormick
    If I wasn't so.....crazy, I wouldn't try to act normal, and you would be afraid.

  2. #2

    Re: Reversing Drum Switch And Split Phase Start Cap Motor

    Need more info on drum switch and new motor
    I hope you did buy a reversing motor they make some wire for one way.

    The 4 wires are how ever wire did not have 4 wire w/ground AKA 5 wire. I seen that a lot on small tools

    If you buy new drum switch I know Grainger the best it the use doors

    Dave

    Quote Originally Posted by William McCormick View Post
    The 1/2 H.P. 120 volt motor on my lathe finally kicked, it was only the start winding points that got fried, but the motor was so dirty and greasy, and it had overheating issues, so I got a new one.

    I looked at the old drum switch, and it was pretty ratty, so I got a new one. A friend gave me the motor, and I picked up the drum switch from Grainger for about sixty dollars with tax.

    The only problem was that I did not have a schematic for the motor and rather than guess and fry the start winding points I figured I would take it apart and I am glad I did. The main lug that I would normally attach the power in, was also tied to the start winding points. So I had to take the two leads off that fed the two-run windings and connect them directly to the neutral out from the drum switch. And then run one of the alternating/reversing, start winding leads out from the drum switch to the main lug on the motor. And then connect the start winding lead from the motor to the output of the start winding points. It worked perfectly. If you ever have to do one, this could save you from frying the points with a direct short. This drum switch only requires four wires from the switch to the motor but you should have a ground too.

    Sincerely,

    William McCormick
    Last edited by smithdoor; 11-03-2018 at 03:28 PM.

  3. #3

    Re: Reversing Drum Switch And Split Phase Start Cap Motor

    That is the drum switch link.


    https://www.grainger.com/product/2X4...!g!81032188557!

    Name:  Splitphasestartcapmotor.png
Views: 79
Size:  1.11 MB
    Name:  lathe.png
Views: 78
Size:  1.60 MB

    That is a piece of five wire SOOW cord going to the motor from the switch.

    Sincerely,

    William McCormick
    If I wasn't so.....crazy, I wouldn't try to act normal, and you would be afraid.

  4. #4

    Re: Reversing Drum Switch And Split Phase Start Cap Motor

    What you cannot see is that between #2 and A, underneath is the start winding points. When the motor is at rest or under a heavy load, it is a dead short between A and #2. When the motor is running normaly it is open between A and #2.

    Connected to the main lug by terminal #2, are two wires, one wire from each of the two run windings. A is where you land a wire from the start winding. The drum switch reverses the two leads of the start winding. To reverse the motor normally you just switch the two start winding leads between A and five.

    But with the drum switch, you have to remove the two-run winding leads that are landed on the main lug near #2 and connect them directly to the switched neutral from the drum switch. And then connect one of the start winding outputs from the drum switch to the main lug by #2 and then one lead from the motor start winding to A, and the other start winding output from the drum, directly to the other motor start winding lead. The hot out from the drum switch goes to the other main lug.

    Sincerely,

    William McCormick
    If I wasn't so.....crazy, I wouldn't try to act normal, and you would be afraid.

  5. #5

    Re: Reversing Drum Switch And Split Phase Start Cap Motor

    This simple but you will need 6 wired to motor due to thermal protection

    Need a wire to red, black, temal 5 and temal A

    Two wires to lines

    Do need to see inside your drum switch
    I do think there has been any change drum switch

    If no changes (front part of switch) caddy corner red and black
    The caddy corner temal 5 and A

    One of line wires goes (back switch) and the plug

    The other line goes to plug note this the white wire

    Dave

    PS looks great South Bend 9 lathe
    I do not thermal protection the slow blow fuses works best for motors.

    Quote Originally Posted by William McCormick View Post
    That is the drum switch link.


    https://www.grainger.com/product/2X4...!g!81032188557!

    Name:  Splitphasestartcapmotor.png
Views: 79
Size:  1.11 MB
    Name:  lathe.png
Views: 78
Size:  1.60 MB

    That is a piece of five wire SOOW cord going to the motor from the switch.

    Sincerely,

    William McCormick
    Last edited by smithdoor; 11-11-2018 at 09:52 PM.

  6. #6

    Re: Reversing Drum Switch And Split Phase Start Cap Motor

    Quote Originally Posted by smithdoor View Post
    This simple but you will need 6 wired to motor due to thermal protection

    Need a wire to red, black, temal 5 and temal A

    Two wires to lines

    Do need to see inside your drum switch
    I do think there has been any change drum switch

    If no changes (front part of switch) caddy corner red and black
    The caddy corner temal 5 and A

    One of line wires goes (back switch) and the plug

    The other line goes to plug note this the white wire

    Dave

    PS looks great South Bend 9 lathe
    I do not thermal protection the slow blow fuses works best for motors.
    You may be right, the start winding is isolated from the thermal protection. So in theory if the motor over heats the start winding would still get power from the drum switch. I am going to look into that. Good looking out.

    Sincerly,

    William McCormick
    If I wasn't so.....crazy, I wouldn't try to act normal, and you would be afraid.

  7. #7

    Re: Reversing Drum Switch And Split Phase Start Cap Motor

    I will probably just bypass the thermal overload. And rely on the breaker to take it out.

    Sincerely,

    William McCormick
    If I wasn't so.....crazy, I wouldn't try to act normal, and you would be afraid.

  8. #8

    Re: Reversing Drum Switch And Split Phase Start Cap Motor

    I believe the thermal overload is between the line input by five, and terminal 5. Terminal four is floating and holds the wire the brown wire, that connects both run windings, if you choose to wire it for 220v.

    The drum switch does not just switch the red and black it powers the red in one position with L1 and the black with L2, in the opposite position it powers the red with L2 and black with L1.

    So I cannot hookup or use the thermal overload. With that drum switch. I just have to stick brown on the terminal right by the main lug by 5 to bypass the thermal overload. I have a 15 amp breaker on the line with the lathe.



    She is running again.

    Sincerely,

    William McCormick
    If I wasn't so.....crazy, I wouldn't try to act normal, and you would be afraid.

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