Repairing/replaceing a small motor

Discussion in 'General Electronics Chat' started by roma, Nov 25, 2013.

  1. roma

    Thread Starter New Member

    Apr 20, 2011
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    This is a follow-up to a post I started more than 2 years ago on advice for repairing a WaterPik, a device that shoots water onto gums of the teeth.


    I've finally gotten back to the repair. I've determined that the battery and the charger do in fact work. The motor doesn't, and there's rust all over.

    There are holes for screws in the casing of the motor, as the attachment shows. As such, it would probably be difficult to find a replacement motor. A friend recommended that I disassemble and clean it up, instead.

    I attempted to do so, but was unsuccessful in prying the motor top open. I have a feeling this motor was designed NOT to be taken apart. Any ideas on how to open it up without completely destroying it?

    Perhaps there is a place out there where I can find a similar motor with screw holes that will fit in the WaterPik casing. Let me know if somebody has ideas on such an online resource.

    Thank you!
     
  2. elec_mech

    Senior Member

    Nov 12, 2008
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    I think you can find a suitable replacement motor. RadioShack sells one that looks very similar. Alternately, you might find one with the same shaft diameter and pull the gear from yours.

    Does the motor move at all or make any noise when you apply power to it?
     
  3. PackratKing

    Well-Known Member

    Jul 13, 2008
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    What is the distance center-to-center in 1/1000's inch of the mounting holes... and the voltage / shaft size of the motor

    Don't hold your breath, I may have a decent one kicking around...:D

    It also looks as though your waterpik has some seal issues, as the motor appears to have been wet more than once...
     
    Last edited: Nov 25, 2013
  4. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    I've repaired motors that size many times. You need a strong dental pick type device (oh the irony) to bend back the two metal tags that retain the plastic endplate.

    Then the endplate comes out and if it is just corrosion and no windings are destroyed the repair is mainly cleaning and re-lubing the bearings and greasing all metal with vaseline etc to reduce future corrosion.
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If repair fails.
    There are literally thousands of miniature DC motors on ebay.
    If you found a suitable one, it should not be hard to carefully drill and tap a couple of holes!
     
  6. PackratKing

    Well-Known Member

    Jul 13, 2008
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    :DAll you need are enough small enough drills and taps, and adequate experience using the same, which most do not have...

    a # 2 / 56 tap is easy enough to find, tho' will snap like a toothpick if not weilded properly...as will any tap...

    Edit...
    The main necessity for micro-tapping, is to not use a device that will not allow good tactile control of the amount of torque you are asking the tap to endure...
    I used these things daily for 25 years - not so much lately, repairing high-end 35mm SLR film cameras, and leaf-shutters...

    Pictures to follow shortly in another post.
     
    Last edited: Nov 27, 2013
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    I would guess from the picture it is at least #4/40?
    If one were to drill the holes first and then get a local small machine shop to tap them if the OP does not have the resources ?
    Max.
     
  8. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Screws are normally 2mm metric thread.

    The big problem will be pressing the gear from the shaft, it's hard to remove and install on the new motor shaft without destroying something.
     
  9. Metalmann

    Active Member

    Dec 8, 2012
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    Yes, I've seen dummies at work drop taps, some costing hundreds; on the concrete floors, and they crack and split like glass.:rolleyes:
     
  10. MrChips

    Moderator

    Oct 2, 2009
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    Darn! Just broke a 4-40 tap finishing the last of eight holes.
    Why? Because I probably got excited about getting the job done and went too fast on the last hole. The sad part of course is that the broken tip of the tap is now stuck in the unfinished hole. Now have to start all over again.

    Luckily there was a horse's hair of a piece of the tap sticking above the work. Not enough to twist the tap with a pair of pliers but just enough to hit with precision jeweler's screw driver and a small hammer in order to ease the tap out.

    Result? A bastard screwdriver - and a broken tap to go into the collection of shortened 4-40 taps.
     
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  11. Metalmann

    Active Member

    Dec 8, 2012
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    What type of tap handle are you using?
     
  12. Metalmann

    Active Member

    Dec 8, 2012
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  13. MrChips

    Moderator

    Oct 2, 2009
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    Pretty much a standard Starrett T-handle as shown in the second link.

    Any recommendations on where to buy 4-40 taps? I need to restock.
     
  14. Metalmann

    Active Member

    Dec 8, 2012
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    The last 4/40s I bought were from Amazon, even comes with the proper size drill bit.

    They are not the highest quality, though.;)

    The main failure of a tap, is keeping it straight, at 90 degrees.

    Look for "Butterfield" for quality.
     
  15. MrChips

    Moderator

    Oct 2, 2009
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    Tell me about it. What's your secret to keeping it straight?

    (Sorry about the hijack but I find this discussion very helpful.)
     
  16. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    I saw something online long ago about putting your tap in a drill press, removing te drive belt and turning the pulley by hand. I don't remember what was used for the chuck since taps are normally square and drill presses have three jaws.
     
  17. MaxHeadRoom

    Expert

    Jul 18, 2013
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    I often use my portable drill and suitable tapping fluid, put the clutch on the lowest setting.
    There is no side pressure that you can often not help even with a T handle.
    Variable speed and reversible to clear the tap.
    I use WD40 on aluminum, copper & brass.
    For ferrous, I use the regular mineral oil based tapping fluid.
    Max.
     
  18. MrChips

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    Oct 2, 2009
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  19. MaxHeadRoom

    Expert

    Jul 18, 2013
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    I usually initially get the set of three and then replace as needed.
    Taper, Second and Plug or Bottom.
    Max.
     
  20. Metalmann

    Active Member

    Dec 8, 2012
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