Electric Seth Thomas Wall Clock Help Needed

Discussion in 'Electric Horology' started by devils4ever, Mar 28, 2014.

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  1. devils4ever

    devils4ever Registered User

    Mar 28, 2014
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    Hi all,

    First post here. Hopefully, I'm in the right forum.

    I have a Seth Thomas electric wall clock that I inherited from my mom's estate. I believe we got it in the 1960s. It has stopped running and I'd love to get it going again. I think it needs a cleaning and oiling since it runs for a few seconds and stops. It has a starting lever to get it going.

    Is this something a mechanically inclined person can do themselves? If so, are there any online guidelines on techniques, materials, etc.? Or, can someone recommend a repair shop?

    Also, I would like to know approx when this clock was made. I'm assuming 1930s or 1940s?

    Thanks.

    SethThomasClock.jpg
     
  2. Willie X

    Willie X Registered User

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    I think that one has a 'capsule' rotor with a coil that slips over the rotor's case. If it runs at all the coil is probably good. Easy to fix ... IF ... you can find a rotor. They, the one I'm think about, disappeared from all the supply houses probably 15 years ago. Might be able to find a new old stock one somewhere.

    A picture of the movement, along with the numbers on the rotor case, will be necessary to make sure you are looking for the right part.

    Willie X
     
  3. R. Croswell

    R. Croswell Registered User

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    If it has a starting lever (that is actually used to start the clock, not just clear a power failure indication) then it won't have a sealed rotor and I would hazard a guess of 1920's After the 1930's I believe pretty much all electrics were self starting. Pictures of the movement would help. With vintage electric clocks I always have a concern about the risk of fire. Personally, I don't run old electric clocks but others think it is fine to do so. You can get a complete new plug in electric clock movement that you should be able to fit to this clock to have a safe reliable time piece.

    If the wiring looks good, you can plug the clock in and leave it alone for about a half hour. The unplug it and feel the motor. If it's warm you may be able to clean and oil the movement and make it go. If the motor is stone cold it's history.

    If we can see pictures of the movement we can better tell what you can and cannot do.

    RC
     
  4. shutterbug

    shutterbug Moderator
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    I recently discovered on Timesavers website a "clearance store" where I was able to get a couple of new coils. They might need to be modified for different uses, but after enlarging the hole in one of them to fit a Telechron motor, and modifying the mount in the case it worked well.
    I just had a peek, and it seems they are gone.
     
  5. devils4ever

    devils4ever Registered User

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    #5 devils4ever, Mar 29, 2014
    Last edited: Mar 29, 2014
  6. eskmill

    eskmill Registered User
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    Thank you for the good photos which reveal an older model ST spin-to-start electric clock motor.

    Do as Croswell explains, "If the wiring looks good, you can plug the clock in and leave it alone for about a half hour. The unplug it and feel the motor. If it's warm you may be able to clean and oil the movement and make it go. If the motor is stone cold it's history."

    Still, make sure the cord and cord cap are not the problem.

    Another possibility is that you may have been fooled by the intertia of the motor by operating the starter lever.

    The function of the starter lever forces the magnetically locked motor's rotor to rotate at a speed somewhat near the 60Hz synchronous rate of the alternating electrical current. A good and well lubricated spin-to-start clock motor will usually cause the sweep seconds hand to continue to advance for ten or fifteen seconds without electrical connection.....or a burnt-out motor.

    Too, it may require repeated use of the starter to put the motor's rotor into synchronization with the alternating current.

     
  7. devils4ever

    devils4ever Registered User

    Mar 28, 2014
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    Thanks for everyone's help so far.

    So, I wired it back up and was able to get the motor running by manually flicking the little metal fork thing. It would run for a minute or two before stopping. So, I assume this means the motor is good. So, does it need a cleaning and oiling?

    I took some more pics of the movement with better depth of field to show the condition of the gears. They are located at the same flickr link in my previous email at the end of the set.
     
  8. shutterbug

    shutterbug Moderator
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    The motor can't overcome wear in the plates. Your clock probably needs to be disassembled, cleaned, bushings installed and re-assembled. Then the existing motor will likely be able to run the train just fine.
     
  9. devils4ever

    devils4ever Registered User

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    Is this something I could do myself or do I need a pro? For a pro, can anyone recommend a reputable shop?
     
  10. shutterbug

    shutterbug Moderator
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    It appears to be a fairly simple time only movement. I'd say it's a pretty good one to use as a learner. If you get in trouble, we can help you. Worst case scenario, you take a box of parts to a pro and let him sort it out for you. Nothing ventured, nothing gained. All of us had a first :D
    If there are two motors, it could get a bit more interesting though. Is it time only, or is there also a strike feature?
     
  11. eskmill

    eskmill Registered User
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    #11 eskmill, Mar 30, 2014
    Last edited: Mar 30, 2014
    I have studied your photos: both sets. Unfortunately they don't reveal enough to provide a sensible answer to give you a good plan of to continue your analysis.

    I could describe more about the inner motor pinion bearing but that is only somewhat visible in your photos. I tried to down load one of your photos to add pointers but your Flicker Fotos are protected from copy thus I cannot provide a description of where to proceed next to discover the fault(s) with the clock works.

    The motor is simple the rear motor bearing is obvious but not the front or innermost bearing which takes most of the thrust load and most likely to wear causing a binding condition when the motor tries to operate the clockworks.

    I believe the front motor pivot bearing is deep inside and is a composite of a "starter" brass gear wheel and a small pinion which engages with the larger diameter brown fiber gear. (the fiber gear with it's fine delicate teeth must be treated with respect....chip one tooth and you may as well put the whole works in the dumper) This fiber gear wheel is the one part of the clock that must have some light grease smeared on it's teeth.

    You ask about a reputable repairer for your Seth Thomas Electric clock motor. I would advise with caution. Many repairers will absolutely refuse to undertake any electric clock. You will either have to repair it yourself or with luck make a good enough analysis to be able to determine why it won't continuously run and take the assembly and your notes and convince the repairer to effect a quality repair of the fault and to service the movement to good condition.

    You could perform some further analysis by simply removing the rear-most plate that carries the motor and while doing so, carefully watch for any small parts such as the shaft that carries the brass starter gear and drive pinion. Carefully examine the pivot end of this motor shaft for severe wear and the brass bearing that carries the inner motor shaft pivot.

    It is possible that the motor bearings are not plain brass but instead, sintered bronze which absorbs light oil.
     
  12. Tinker Dwight

    Tinker Dwight Registered User

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    I as thinking, If people are worried about fires, once the
    old wiring has been replaced, one can get a thermal fuse
    from an appliance shop an tape it to the motor.
    If the temperature exceeds the set point it will open
    and stop any continued heating.
    Tinker Dwight
     
  13. shutterbug

    shutterbug Moderator
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    I'm going to move this to the electric clock forum for more exposure.
     
  14. R. Croswell

    R. Croswell Registered User

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    I think these are mostly used in heating appliances and have to get pretty hot to open. I have also used low amp glass fuses (used to be available at Radio Shack) in fractional amp sizes in series with the motor. One of the hazards is that people often replace the line cord and splice onto the wires going into the motor while the motor wires remain in bad shape.
     
  15. Tinker Dwight

    Tinker Dwight Registered User

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    Hi
    Digikey list these from 151F to 464F.
    I'm sure something about 200F would be fine.
    Wiring still needs proper upgrade.
    Tinker Dwight
     
  16. devils4ever

    devils4ever Registered User

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    It's time only. I'll try to disassemble it a bit more and take some more pics.
     
  17. devils4ever

    devils4ever Registered User

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  18. eskmill

    eskmill Registered User
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    #18 eskmill, Apr 1, 2014
    Last edited: Apr 1, 2014
    Nice photos that I am able only to copy for edit a blurry thumbprint.

    Clean the dirt off the brass bushing bearing and look at the bore. If it is egg shape, the bearing must be replaced.

    Additionally, carefully rotate the large fiber gear with a toothpick and watch for a chipped or broken tooth. Any broken tooth is a bad situation and cause for serious repair.

    I put an arrow pointing to the inner motor bearing....it must be a good fit, clean, well lubricated and perfectly round without more than 0.005" out of round.

    I should also remark that the rotor can be pulled out of the field assembly for inspecting the outer bearing and shaft pivot. Note also that the motor will not operate without the long inner shaft supported as there is only the outermost bearing supporting the rotor assembly.

    I can also state that this design motor will be difficult to start because it is so tightly magnetically coupled to the field assembly it has to be spin started exactly in phase with the magnetic field.
     

    Attached Files:

  19. devils4ever

    devils4ever Registered User

    Mar 28, 2014
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    Eckmill,

    Thanks again.

    Sorry, you are having such trouble with my pics, but I'm not sure why you are having difficulty downloading them. I wasn't logged into flickr and was able to download one in many different sizes including original. I just clicked on the photo of interest, clicked on the 3 horizontal circles on the right side of the page, and selected "Download / All sizes".

    In any case, I selected the 1024 x 683 size and attached it here.
    IMG_4300_edited-1.jpg

    I used a tiny amount of mineral spirits (I hope this is okay) and cleaned the bushing where the motor shaft goes. I added a tiny drop of light machine oil and reassembled. I rewired the motor and I had it running for minutes until I stopped it. You are right that starting the motor can be tricky. You have to match the speed closely to get the motor running. But, I remember that growing up as a kid, it took a few tries to get it going.

    I took it apart again and examined the large fiber gear. It seems to be intact and I see no missing teeth.

    So, I guess the next step is to disassemble again and examine the bushing more closely. I have dial calipers, but how do I measure the hole on something so small?

    Also, my plates appear to be steel, not brass. Other clock mechanisms I've seen online are brass. Is this an issue?
     
  20. Tinker Dwight

    Tinker Dwight Registered User

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    Put a small round piece in that has some clearance.
    measure how much it wiggles.
    It looks like the rest of the train could use some cleaning
    and fresh oil as well ( it is always hard to tell from a picture ).
    There should never be enough play in the bushings of the
    armature that the armature touches a pole surface.
    Tinker Dwight
     
  21. devils4ever

    devils4ever Registered User

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    What should I use to clean and oil the movement? Is paint thinner and 3 in 1 oil good?
     
  22. Tinker Dwight

    Tinker Dwight Registered User

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    It does need to be take apart to clean.
    You only put oil on the bushings and pivot, not on the gear teeth
    ( with the exception that the fiber wheel is usually lightly oiled ).
    Some of the gunk may need scrubbing. Use tooth picks to clean
    the bushings.
    I use kerosine for cleaning by hand but use what works.
    Tinker Dwight
     
  23. devils4ever

    devils4ever Registered User

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    Thanks, Tinker. I guess I'll have to bite the bullet and take this apart. It's very intimidating with all those parts! :eek:

    I've read a lot of people use ultrasonic cleaners. I might be able to get one. Otherwise, I"ll see what I can get.

    So, do I need clock oil?

    What is the purpose of the fiber gear? Why was this used? Should I add oil to the teeth?

    I may try just disassembling, cleaning, and oiling first. See how it runs before doing any repair work.
     
  24. eskmill

    eskmill Registered User
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    #24 eskmill, Apr 3, 2014
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    devilsforever asks: "So, do I need clock oil?" Yes and no. A teaspoon of Mobil 1 0-20 or 5-30 (or any synthetic engine oil) will do a dozen of what you are working on. Just one drop on each pivot end where it protrudes through the plate.

    What is the purpose of the fiber gear? Why was this used? Should I add oil to the teeth? The fiber gears are quiet running. If it was a brass or metal gear, it would growl and and wear out. Either oil or other light petroleum grease just on the fiber gear teeth.

    Oil on clock gear teeth is generally a no-no because it attracts and imbeds abrasive dirt. However, for electric motor driven clocks, where the gear ratios are opposite a spring or weight driven clock or watch, lubrication of the gear teeth is imperative due to the relatively high speed of the driving pinions.

    This is especially true for the fiber gear used in electric motor driven clocks. The delicate tooth fibers must be lubricated because the fibers are bonded into shape with old-fashioned phenolic resin. The fiber teeth are strong only in the direction that the steel pinion on the motor meshes.

    Don't oil gear teeth that move very slowly.
     
  25. devils4ever

    devils4ever Registered User

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    To disassemble to clean, when I try to remove the top plate, do I need anything to pull the top gears off?
     
  26. eskmill

    eskmill Registered User
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    The "top" gears or the ones that carry the hands must come off. Before removing the outermost or top plate, make a pencil sketch of their relative position and direction. This to avoid re-assembling with a wheel-pinion pair up-side down. Try to understand what each wheel and pinion is doing.

    You should, now with the motor removed at the rear, be able to manipulate the large fiber gear with a tooth pick several turns to see if there is any binds further down in the gear train that is causing the works to fail to run continuously.

    Once you have the front plate off and all the down-stream wheels and pinions removed, replace the front plate and replace the motor so that the motor outermost shaft is supported in the front plate bronze bearing. The motor now can be tested electrically and mechanically. It must be able to run continuously once started and running.

    My reason for testing the motor without any mechanical load is to assure that the rotor tips are well magnetized.

    Your electric clock movement does not have a rear-setting knob....this makes the job even easier.
     
  27. eskmill

    eskmill Registered User
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    #27 eskmill, Apr 3, 2014
    Last edited: Apr 3, 2014
    In my previous reply, I alluded that the motor rotor tips must be magnetized.

    Refer to your Flicker Photo #4298. The rotor has pole tips that extend over the field rotor poles. These must have some permanent magnetism. Check with a piece of iron such as the tip of a screw driver to assure that each of the four tips is magnetized.

    Better to use a small magnetic compass. The pole tips on the rotor should be alternately north and south because this is an AC synchronous motor of early design.

    There could be a condition that caused one of the four rotor pole tips to loose it's magnetism....usually due to mechanical shock or having come into contact with one of the fifteen field pole pieces when energized.

    I have added a photo showing the rotor pole tips that have to be permanently magnetic....
     

    Attached Files:

  28. devils4ever

    devils4ever Registered User

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    Great info!

    So, can I use small screwdrivers to gently pry off the large gear that drives the second hand and the smaller one that drives the large gear? Or, do I need a gear puller?
     
  29. eskmill

    eskmill Registered User
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    Please don't use screwdrivers to pry the wheel and pinion off.

    The large wheel that the sweep second hand presses onto should fall off in your hand. And the pinion, in my opinion does not have to be removed. It was probably assembled onto it's arbor while the movement was first assembled. It might even be threaded onto the arbor.

    You are into an area that I cannot help with simply because I don't have the movement in hand and have not disassembled one exactly like yours.

    Have you determined that the motor rotor tips are magnetized? It is rare that the rotor of these purely AC synchronous motor pole pieces loose their magnetism but it has been reported. Restoring their magnetism can easily be done with a small, button shaped ceramic or neodymium magnet.

    Testing the rotor poles for their magnetism is so quick and simple, that it is something that you should try before any further testing or diagnosis.
     
  30. devils4ever

    devils4ever Registered User

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    Well, I got the nerve to disassemble the movement. I cleaned it as best I could with lacquer thinner and a small brush. I checked the rotor and it was magnetized. I tried to get the big wheel off the front, but couldn't. I realized it was attached with a "C" clip. Here's the closeup. I partially reassembled so I could run the motor overnight to make sure it's okay. I added more photos to my flickr account which show the process, if anyone is interested.

    IMG_4319_edited-2.jpg
     
  31. devils4ever

    devils4ever Registered User

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    Motor ran fine overnight. So, I decided to put this thing back together.

    I'm have fun trying to line up all the parts! Is there a trick to this? Getting all those little shafts lined up with their respective holes in the plates is getting frustrating.
     
  32. devils4ever

    devils4ever Registered User

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    Finally, got the movement back together. I did notice some "play" where the motor shaft meets the bronze(?) bearing.

    Put the entire clock together and it runs! It's been running now for over a day. Hopefully, it will continue running for years to come!

    Thanks for everyone's help!
     
  33. eskmill

    eskmill Registered User
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    'Glad to know that you have mastered the clock movement and have it running.

    You have stated that the motor shaft has some "play" in the bronze bearing and that's not a good situation.

    End "shake" or some sloppy fit allowing some up-and-down motion of the motor and pinion shaft is permissible and normal. However any significant wear in side-to-side play or sloppiness is generally the signature of wear leading to end-of-life for the mechanism.

    Wear of the bearing and shaft will always be in the direction of side thrust generated by the tooth engagement of the pinion and the fiber gear wheel. When finally the bearing hole becomes too large, the pinion teeth will jam the fiber gear teeth and stop the motion. Further attempts to force the engagement will destroy the teeth on the fiber gear.
     
  34. devils4ever

    devils4ever Registered User

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    I guess I can try to replace the bronze(?) bearing in the plate. It should be straightforward since it's a bearing already and I don't need to re-center it. Does anyone know where I can get a replacement? I got a copy of "The Clock Repair Primer" by Balcomb from the library. It only covers bushing repairs, not replacing a bearing.

    Hopefully, I can enjoy the clock running again for a month or two without any serious damage. It great to see it running again. :excited:
    I guess I'll have to take it apart again to take some measurements. :mysad:
     
  35. eskmill

    eskmill Registered User
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    'Doubt you will readily find an exact fit sintered bronze bearing that is pressed in the innermost plate. I will dismantle the wreck I found a week ago and if the bearing isn't too bad, I will snail mail the identical motor. What's missing is the fibre wheel. You might simply replace the uppermost plate bearing and all. I first have to find it and examine the wear.

    Sintered bronze bearings are porous and the voids absorb light oil lubricants. Far different from the "king-pin" bushings of ancient auto repair.

    PM me with your postal address.
     
  36. devils4ever

    devils4ever Registered User

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    Wow! That's very generous of you. PM sent.
     

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