I need to build a forward/reverse switch for an AC electric motor

Discussion in 'The Projects Forum' started by Highdensity10, Jan 18, 2016.

  1. Highdensity10

    Thread Starter New Member

    Jan 18, 2016
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    I was gifted an old high torque right angle drill, but the tricky part is that there is no forward/reverse switch, and the leads were all cut off inside the handle. The motor is 120v AC and 3.8A.

    Unfortunately it's old enough that the switch/trigger assembly is discontinued and despite much searching, I am unable to find it anywhere.

    I've done enough messing around with it to figure out how to get it to run. That's the easy part. I've got 4 wires in there. Two going to field and two going to brushes. If I put hot to one of the field wires and neutral to one of the brushes and then connect the other field/brush together, the drill rotates one direction. If I swap the brush wires, the drill will rotate the other direction.

    My issue is trying to figure out how to cobble together something that will accomplish "swapping the wires" small enough to fit inside the handle, or at least minimize exterior modifications.

    I do not have a lot of experience with small circuitry, but I am a fast learner. I can solder pipes together and I can wire electrical in a room of a house, so that has to count for something, right?

    Thanks for any advice you can offer.

    :)
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    Any simple switch you can get which is able to be mounted. Wire it for one direction only, then add a toggle switch (maybe room inside to put in handle?) That reverses your brush wires. Two brush wire configurations one on each end and wires to your squeeze switch from the middle.
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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    You need a DPDT switch with centre off.
    As you may have found out, the field is in series with the armature and you reverse the field connections WRT the armature to reverse.
    Max.
     
  4. StiffCookie

    New Member

    Jan 18, 2016
    8
    2
    Hey!

    I personally would use a DPDT switch for that purpose. You can get them in all shapes and sizes. Here I even drew a little diagram in MS Paint for you! :)

    Regards,

    [​IMG]
     
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  5. Dodgydave

    Distinguished Member

    Jun 22, 2012
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  6. Highdensity10

    Thread Starter New Member

    Jan 18, 2016
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    That is exactly what I thought I had needed but the way I was picturing wiring it didn't make sense in my head, so I omitted that idea from the original post to avoid complicating it.

    So what you have there on the right is the motor... the little dots indicating the brushes?

    And on the left you have L and N. In electrical I'm used to labeling them as line and load or hot and neutral. I'm assuming that is what the L and N are?
     
  7. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Highdensity10 likes this.
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    IMO you need a centre off position, otherwise you can go from full fwd to rev, doing so you blow the motor or the fuse, there are special toggle switches made for this that have a centre off and also includes a prevention of going from fwd to rev through the off position in one motion.
    Max.
     
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  9. Highdensity10

    Thread Starter New Member

    Jan 18, 2016
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    0
    Typically these drills have a sliding switch in the handle so I'll have to see if I can find that variety at radio shack this weekend.

    :) Thanks everyone. I'll update the progress when I get it running 100%.
     
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