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Armature question...Growler??

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  • Armature question...Growler??

    Still fooling with this Enco power feed. I went to a local battery/alternator shop looking for brushes and the guy said it doesn't sound like the problem because the brushes look OK. So I go home, get the armature and fight traffic all the way across town. The guy takes one look at it and notices a broken winding, he puts it on the "growler" (Some mysterious machine in back) and pronounces it dead. He says I may be able to re solder the winding... I fight traffic home and solder a piece of copper strand back in there being careful not to disturb the laquer on the rest of it and wrap it in some cardboard tucking it back in. I put the whole thing back together run it foe a few seconds and the overload pops out. Back to square one...
    The surface where the brushes run have little grooves in between the "bars" isn't there supposed to be potting compound in there? The brushes are still leaving a black streak on the armature like peeling out on a driveway...
    I'm just not giving up yet. If it didn't run at all it would be different.
    I was thinking about putting some high temp epoxy or something in the grooves and then making a skim cut on the armature and putting new brushes in it. The "growler" will have to wait till next week.

    ------------------
    Hoffman in Warner Robins Ga
    Techno-Anarchist

  • #2
    Don't put anything in those grooves. There is normally mica insulating material between the segments of the armature.
    I would take it to a starter rebuild shop and have them reinsulate the windings. When
    they get an armature that is shorted to the core They will tap the end of the armature against a piece of metal and put it back on the growler to see if the winding is clear of the core. If it is they dip it in an insulating liquid and bake it in an oven to solidify the insulation.This will normally take care of a short against the core.
    If it has an open winding that requires repair or replacement. The black streaking
    on the comuntator is just carbon and caused
    by arcing , it can also be caused by the absense of electricity which acts like a lubricating layer between the brush and the comuntator. The brushes would wear out very fast if the electricity was not there between the brush and the comuntator.

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    • #3
      The problem may be a common item as I had one in the shop a couple years ago and it had an open winding in the armature. Too much trouble and costly to rewind. It can be done if you have the inclination and the correct size wire. Balancing is another problem. Does Enco offer any repair parts? The commutator must be in good condition from your comments.

      JRW

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      • #4
        I'm thinking it has an open winding. I put some different brushes in it and the overload stopped kicking out but if it stops in a certain spot it won't start. If I could find the short I'm sure I could fix it but I'm not sure about troubleshooting to isolate it. I checked continuity from the armature segments to the shaft and none are grounded there. There is continuity between all the slots except for 4 of them. Not sure what it means.
        It's just something to fool around with and maybe learn something in the process.

        ------------------
        Hoffman in Warner Robins Ga
        Techno-Anarchist

        Comment


        • #5
          Dead segments = broken wire.
          Make sure you didn't knock a few loose when you turned the commutator. These can be soldered or just crimped in. You should have resistance that varies from about 20 to 60 ohms between pairs.

          Is the Enco armature the same as the Servo? I have a model 90 that's captured in a box. I don't think I'll ever get it back together. If it's the same, you're welcome to it. (I guess I should check it before I offer it.)

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          • #6
            Thanks Ken. I have a Servo drive that needs a zytel gear. (Big plastic one on the bottom) I may be interested if you have one. I'm not sure if the armatures are the same but I doubt it. I'm fixing up the Enco to serve as a quill feed for my Gorton mill. Back to work tomorrow and then christmas stuff for a few days. I'll check the wires at the comm. when I have time they are staked in with copper pegs. Email me if you have a zytel I'm interested.

            ------------------
            Hoffman in Warner Robins Ga
            Techno-Anarchist

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            • #7
              What model Servo do you have? Do you need the drive pin to?

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              • #8
                After you turned it, did you get all the shavings out of those grooves?

                The grooves are supposed to be there, but any shavings between will cause a short of at least one coil. That will be discovered on the "growler", and might be the problem that was found.

                You would hope the motor shop guy would have scraped them out and tried again, but......
                CNC machines only go through the motions.

                Ideas expressed may be mine, or from anyone else in the universe.
                Not responsible for clerical errors. Or those made by lay people either.
                Number formats and units may be chosen at random depending on what day it is.
                I reserve the right to use a number system with any integer base without prior notice.
                Generalizations are understood to be "often" true, but not true in every case.

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                • #9
                  " it can also be caused by the absense of electricity which acts like a lubricating layer between the brush and the comuntator. The brushes would wear out very fast if the electricity was not there between the brush and the comuntator."

                  That's an interesting comment. Where can I find out more about this?
                  I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

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                  • #10
                    I got all the shavings out of the grooves. Ken, I have the drive pin, it's a servo 140. I'll post the dimensions of the gear after work. Think I'll check the connections tomorrow.
                    Thanks for all the help guys!

                    ------------------
                    Hoffman in Warner Robins Ga
                    Techno-Anarchist

                    Comment


                    • #11
                      Hi Darryl,
                      Take a carbon brush and drag it across something, it will leave a carbon streak on the surface. Take a generator without any output and spin it and the carbon will come off on the comuntator. However if it is generating power it will spin for thousands of hours without any significant wear.
                      The difference is the electrical flow between the comuntator and the brush.
                      I will venture to say that most of the wear on a normal set of brushes occurs when starting and stoping. A set of brushes should be replaced if they are 1/2 of their original length.

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