Hammond clock motors

Discussion in 'Electric Horology' started by Thomas Kelley, Apr 1, 2020.

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  1. Thomas Kelley

    Thomas Kelley Registered User
    NAWCC Member

    Mar 22, 2018
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    As a preamble....I have limited clock repair training but have played around with it for about 8 - 10 years and one of the clocks that got me started was the Hammond synchronous. The simple but accurate time keeping design grabbed my interest. Electro-mechanical clocks remain my major focus but I am working on expanding my knowledge now that I have retired and find the NAWCC to be an invaluable resource. I am very much hoping the National Convention is still able to take place in June (becoming less optimistic I'm sad to say!) as I am looking forward to gaining additional clock repair knowledge.

    The question I have is......sometimes, after cleaning and repairing a Hammond clock, the motor can sometimes be noisy and the spin to start doesn't want to catch like it does in the majority of my clocks. It's like there is resistance somehow. The mechanical aspects of the clock are perfect as far as I can tell. Could it be a polarity issue?
    My Hammond mantle clock is having these problems and I could live with the minor running noise but I find the clock is stopping once or twice a week and, as I mentioned, starting is not as smooth as I know it should be.
    What can I test or check to try and correct this? Would replacing the coil be a start even though it appears not to be damaged?

    Any guidance anyone could provide would be greatly appreciated.
    [​IMG]
     
  2. Uhralt

    Uhralt Registered User
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    Sep 4, 2008
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    I have a Hammond "Skyscraper" clock that had similar symptoms, but I'm not sure if it has the same motor as yours. In mine, the rotor can easily be detached from the coil. It is completely sealed. I noted some stickiness when I manually turned the pinion, especially when I pulled it out a bit. The first thing I did was to replace the old oil inside the rotor. There is a little plug soldered on the side of the rotor. This needs to be unsoldered. Now I sprayed some carburetor cleaner into the opening, swiveled it around and let it drop out. I repeated this until it came out reasonably clean. Then I let it drip out completely. With small syringe I filled in about 3 ml of Mobile1 5-20 synthetic motor oil. Soldered the plug back in and the motor ran beautifully.

    Uhralt
     
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  3. Thomas Kelley

    Thomas Kelley Registered User
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    Mar 22, 2018
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    I appreciate your reply. I have several Skyscrapers and their one of my favorite Hammonds. Those have a sealed rotor whereas I am referring to open rotor models. I have just started to appreciate the sealed rotor design and enjoy working on them.
     
  4. Dave T

    Dave T Registered User
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    Dec 8, 2011
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    #4 Dave T, Apr 7, 2020
    Last edited: Apr 7, 2020
    Can you post a picture of the "open rotor"?

    This thread goes through my learning experience on these motors. And until I removed the solder plug as stated above, flushed it out, and replaced with fresh oil mine was doing the same thing you describe.

    Sessions Electric Wall clock with Hammond motor
    It works great now!
     
  5. Thomas Kelley

    Thomas Kelley Registered User
    NAWCC Member

    Mar 22, 2018
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    You can tell the type of motor your Hammond clock has by the back plate. I include a picture I "borrowed" from Craig Shields' book on Hammond Clocks Maintenance and Repair. Excellent book and highly recommended. It covers both closed and open rotors. It may be available thru the NAWCC, I haven't checked.
    The picture shows the rotor with torsion spring and brass weight.

    IMG-4246.jpg IMG-4247.jpg
     
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  6. Al Dodson

    Al Dodson Registered User
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    Aug 22, 2019
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    The noise as it runs is probably due to wear of the bearings. These are from a fibers material. Delrin plastic makes a great substitute and are easy to make from 3/8 inch rod which is the OD of the existing bearings. The fit of the pivot hole is very important as this is where the noise comes from.

    I have the open rosters can be hard to start if the stator pieces (the toothed segments) are too close to the rotor. If you loosen the screws holding the coil, you can adjust them. If the coil screws are loose, you may hear a buzzing sound. If the problem is loose bearings, it will be more of a rumbling sound.

    Another problem I’ve found with these later type of Hammonds is the deterioration of the lead wires from the coil. Unwrapping the covering of the coil and soldering new leads is a delicate operation but it is possible.
     
  7. Thomas Kelley

    Thomas Kelley Registered User
    NAWCC Member

    Mar 22, 2018
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    Great advice about the stator / rotor proximity. On the clock I recently repaired, I did have the coil and stator assembly out to solder new wires to the leads (it is a delicate operation!) and I'll bet when I put it back, the positioning may not have been exactly as it should be. I didn't notice that there was any "play" in the positioning to do this but then, I didn't look for it. I will give it a try (once our power comes back on from a storm last night!)
    Thanks again for your assistance! I'll let you know how it goes.
     
  8. Thomas Kelley

    Thomas Kelley Registered User
    NAWCC Member

    Mar 22, 2018
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    I adjusted the distance between the rotor and and the stator and it did help but still had noise. I put a "new" rotor in and the the noise is much less - tolerable (my wife doesn't hear a thing! LOL)
    I probably have some wear on the pivots that I will need to address at some point but for now, the clock is running reasonably quiet and accurate.
    Thanks again for your guidance.
     

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