antique electric motor repair Q

Discussion in 'Off Topic' started by machiasmort, Oct 20, 2010.

  1. machiasmort

    machiasmort Active Member

    I'll be looking around the internet for an answer but figured I'd tap the knowledge of my Brother's here on the board first.

    I'm rebuilding an old brushed motor from the 50's.

    I broke the brush board removing the armature. I need to glue or replace the board? Don't know what I should do? Or what materials to use.

    The board needs to be strong but heat resistant and non conductive.

    Thanks guy's. P.S. Just a thought, sculpey clay would be easy to use, don't know if it would hold up to the heat?

  2. Sculpy will hold up to the heat, but has no strength. It would break during reassembly. I would epoxy it back together, making sure it is perfectly clean prior to glue up.
  3. machiasmort

    machiasmort Active Member

    Hey man, thanks! That's what I was thinking when I wrote the post also. Figured I'd get input... I used the black two part stuff that comes in a syringe. Hope it takes the heat! Seems like it stuck real well. I cleaned the board w/alcohol then sanded the surrounding areas. I was broke in 4 places tho! I'll let you know how I make out. Hopefully the brush holder don't come loose and hit the motor case. ZAP! Don't want to be standing in water if that happens!
  4. jimraysr

    jimraysr Member

    Broken Brush Board

    I am guessing the board is brown or tan? Bakealite or some other material used before fiberglass.

    I would try to epoxy a blank circuit board (green fiberglass) to the back if there is space. Radio Shack may have some, but more likely theirs would have copper plating on one side.

    If no space then would make a new on from the fiberglass material. Problem would be that brush holders are generally brass riveted to the board?

    The fiberglass should give you both strength and temperature resistance.

  5. machiasmort

    machiasmort Active Member

    Jim, good idea but the brush stakes wouldn't have fit thru the other side to be peened over! Thanks, you made me say "why didn't I think of that"!

    My fix worked and the motor is running but sounds like a 2strk sputtering.

    I hope it smooths out?
  6. jimraysr

    jimraysr Member

    Motor Sputter??

    It has been my experience that a sputtering universal (AC / DC or DC only) motor makes noise when the brushes don't fit the curve of the communicator or the communicator is rough. Generally the copper segments will turn black if there is arcing do to poor connection to the rotor?

    You probably can't see the arcing when the motor is assembled, but the sound is a giveaway.

    I am sure you know this, but if the brushes are put back in the holders turned 90 degrees the curve in them won't fit the communicator.

    Last edited: Oct 25, 2010
  7. machiasmort

    machiasmort Active Member

    I've never heard a motor run this rough!!! LOL! It is starting to smooth out and yes, I did put the brushes in properly LOL! You think differently by the way it runs though!

    Is it communicator or commutator? I always thought commutator? But either way, what might be causing some of it, I laid two small washers dirrectly on top of it, held in place by the spindle (runs through center). I did this because another brass friction bearing was slidding on the spindle and wasn't contacting it's race that was built into the motor case.

    Don't know if you guys could envision what I'm saying? But the washers on top of the commutator worry me that it's safe to have them there? It's the only way I could think of keeping the brass bearing forced up to make contact with the other half of it's housing. I lucked out because the washers were perfect thickness and there is very little slop! It's to an old "precission" engraving machine!
  8. jimraysr

    jimraysr Member

    Commutator is the word. Communicator is the result of too quick a look at word check suggestions. 8O) = I would guess I have used the term thousands of times in conversation (being really old) and only seen it in print a few hundred times?

    When my contemporaries and I were taught to read, it was called "sight reading". No phonics. The reader was called "Streets and Roads" with Dic. (not Richard), Jane and Spot. If you haven't seen a word before, may not be able to pronounce it, and very likely not be able to spell it later.

    So I rest my case. Glad your project is functioning better.

    You are using the washers as spacers on the shaft? taking all the play out on one end might push the brushes toward an end of the COMMUTATOR not used before? Obviously to far towards the solder terminals would be really rough.

    Last edited: Oct 25, 2010
  9. machiasmort

    machiasmort Active Member

    I'm glad you are taking me correctly because I appreciate the input!

    Yes the washers are on top of the shaft and laying directly on top of the commutator. The brass bead bearing slides onto the shaft and is located above the washers, making contact with the bearing race on the housing (shell) of the motor.

    I presume that the cells in the commutator are insulated from the shaft? Am I correct?

    That was a very good thought on using a new surface on the com! I think thats what might be going on. The brushes were worn into the bottom of the com and now are hitting slightly higher (toward the middle), because of the bearing pushing the assembly down!

  10. jimraysr

    jimraysr Member

    There used to be mica sheets between the segments as an insulator. The mica had to be undercut to keep the brushes from skipping when a commutator was resurfaced. I assume the shaft insulator is longer than the segments to keep the commutator from shorting against the end bell or the bearing?

  11. ibdennyak

    ibdennyak Guest

    Jim, you are really funny. *being really old*, Perfect reasoning.

    You are about 10 years older than me, so I must have just started with phonics in about 2nd grade. I distinctly remember Miss Iauch telling me to "sound it out" before hitting me with the ruler. Aaaaah 2nd grade....spent 4 of the happiest years of my life there.
  12. SimpleSimon

    SimpleSimon Active Member

    Denny, I can identify with the ruler bit. My first and second grade teacher (it was a really small school) was Mrs. Emch - a true dragon of Teutonic motherhood. She and I went round and round and round, as my Dad taught me to read by sight reading long before I started school, and I truly despised the **** & Jane readers. I refused to learn phonics.
  13. I use fine emory cloth to polish the comutator/brush rings whenever I rebuild a DC motor/brushed AC motor. You can put the rotor shaft in a drill press or lath chuck to turn as you polish, or if the shaft is too big you can just hold the rotor between your knees and turn it regularly as you polish the copper. A smoothly polished comutator and new brushes will arc a little until the brushes wear into the comutator, like breaking in rings to a cylinder. If the comutator is rough the brushes will tend to "bounce" and arc on the comutator.
  14. fasteddy

    fasteddy Member

    ****,Jane and Spot the dog. "Look ****, see Jane run". Great. Thanks fellas, now I'll have nightmares if I can get to sleep at all.

    ibdennyak, I know the feeling. Spent 3 very comfortable years in grade 5. The only bonus was every year the work got easier.
  15. machiasmort

    machiasmort Active Member

    By the time he was 25 in 11th Grade, life got even better w/ a car on the road and knowing what the girlies liked! LOL! Sorry FE!
  16. fasteddy

    fasteddy Member

    Marty, who talked? LOL

  17. SimpleSimon

    SimpleSimon Active Member


    You know who I mean, don't pretend you don't.
  18. jimraysr

    jimraysr Member

    2nd Grade

    Boy, I skip a day on line and you guys take everything and run.

    Talk about nightmares? I had forgotten 2nd grade. Miss Mastsha had spent the year before teaching in Hawaii.

    She came back to Phoenix and we spent the year in grass skirts. Producing shows and making buts of ourselves going to other schools and putting on these shows.

    Nothing else learned that year! You haven't lived till you see a chubby little (round tummy and all) kid with red hair in a grass skirt.

    I am assuming we have solved all the commutator / brush problems and the motor is happily pushing a bike up hill at 30 MPH with a 25 year old 2nd grader at the controls?

  19. fasteddy

    fasteddy Member

    Which Loretta?

    Jimraysr, just can't turn your back here even for a minute.

  20. machiasmort

    machiasmort Active Member

    LOL! You guys are too much!

    Is that the one he told he was only 17 Simon?