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Thread: took apart 3 phase motor. Rotor and Stator are worn. Wondering if its OK?

  1. #16
    Join Date
    Feb 2017
    Location
    Rochester, NY
    Posts
    78
    OK so after taking it apart again I measured the od of the new bearings and old ones with a micrometer. They are the same size. I had no noise/play with the old bearings. I also set the old bearings in the journals and checked play and tried to slide a .0015 feeler gauge between the bearing o.d and journal. As far as I can tell, the journal has zero wear. When I lay the endbell flat and set the new bearing in it (the rotor and shaft are pointing straight up), I can feel the play I was feeling before. So, I think it might actually be coming from within the bearing itself. Not sure if this is normal/OK but like I said, I bought cheap sealed bearings from ebay. They were $13 for both. There is actually grease leaking around one of the seals already. I am now wishing I had just left the shielded Japan bearings in it that did not give me issues...

  2. #17
    Join Date
    Nov 2003
    Location
    Central North Carolina
    Posts
    1,104
    If it was mine, I would clean and de-grease the bearing hole and the outside of the outer race of the bearing and then put some blue Loctite on the outer race of the bearing, then re-assemble the motor. The blue Loctite will keep the outer race of the bearing from spinning until the bearing goes bad. In use as a rotary phase converter, the motor is just coasting most of the time. There is a brief load on the windings whenever you are starting up another 3 phase machine, but then this motor is just coasting again. I doubt that you will ever need to take this motor apart again when using it this way in your home shop. It's good enough for your needs. Get on with your life.


    Charley

  3. #18
    Join Date
    May 2008
    Location
    Peshtigo,WI
    Posts
    701
    According to the data plate in your other post you need a 6206 and a 6205 bearing. You can buy them with shields or seals, won't make a difference if your motor is totally enclosed, data plate says uniclosed but I don't know what that is. I would get the bearings with seals myself and you take out any doubt about the frame.

    I would go to a bearing supplier...maybe Motion Ind. and buy SKF bearings, ignore the country of manufacture they're good bearings, and they shouldn't cost a whole bunch. The SKF numbers would be 6206 2RS C3 and 6205 2RS C3. 2RS means a rubber seal on each side and C3 is the internal clearance of the bearing.

    If you think there is excessive clearance in the end bells use GREEN sleeve retainer to hold the bearing in the end bell. Green is designed for this application, Blue, Red, and Purple Loctite is designed as a thread locker not a sleeve retainer. To be exact I would use Loctite 641, it will fill a .008 diametral gap and can be disassembled without heating should you need to replace bearings in the future.

    I also wouldn't worry about greasing the bearings in the future, they'll last a good long time especially if there's no radial load on them. Just be sure to pay attention to the way they sound while the motor is running and change them out right away when you hear them start to fail.

    We have 20 HP motors at work on a shot blaster that run sixteen hours a day with about 50 pounds of weight on the shaft at 3600 RPM and they haven't been greased in three years and they are running strong yet.
    Confidence: The feeling you experience before you fully understand the situation

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