Help with Gruen wristwatch
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  1. #1
    Member ThorBob's Avatar
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    Help with Gruen wristwatch

    A somewhat beat up Gruen wristwatch came my way, and I would appriciate some help with it. From the looks of it I'd estimate that its from the 70's (based on the case design), but I have been unable to verify much about it.

    The watch has a day/date funtion, with the day "number" in front of the day (for some reason). The case is "golden" finish, but I have no idea about the actual type of finish. The caseback is stainless steel. The dial is silver, with raised gold numerals. The dial reads " Gruen Precision", "Automatic Incabloc".

    The outside of the caseback reads "Stainless steel back, Water resistant, Anti Magnetic, Swiss Incabloc, Automatic". On the inside of the caseback a faint inscription seems to read "NK 10/IX 75" (possible manufactor date?). The rotor reads " Gruen 03, 25 jewels Swiss Made", and I *think* I can read a "ETA" logo and the an inscription saying "HX 2789". Would this make it a ETA 2789 movement?

    Finally I find that the watch will run while on my arm, but even after a full day of wearing it, it will "run down" after a couple of hours. I find the crown very hard to turn (as in winding it). Should it be possible to hand wind this watch?



    Some pix:










    I appriciate all and any info on this watch!


    Thor

  2. #2
    Member AbslomRob's Avatar
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    Re: Help with Gruen wristwatch

    Hi ThorBob. You're probably right about it being an ETA 2789: http://www.ranfft.de/cgi-bin/bidfun-...2uswk&ETA_2789

    The inscription inside the caseback was probably made by the watchmaker who serviced it; I'd guess it was serviced in 1975, which would probably mean the watch was purchased closer to 1970 (5 years was a typical service interval for that era). Other then that, it has no significance (unless you happen to know who did the service, in which case you could use that number to look it up in his books).

    Likely it just needs a service; it was common to use natural oils (whale oil was popular, until its use was banned in the US). These oils dry out over time, and are likely preventing it from winding efficiently. I'd stop wearing it until you get is serviced; the lack of oil is liable to damage the internals. You <could> manually wind it, but the winding mechanism is really designed for the lower torque of the autowind module. And as above, if it's gummed up you don't want to force it.
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  3. #3
    Member ThorBob's Avatar
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    Re: Help with Gruen wristwatch

    Thank you so much for the excellent info! Any pointers as to where I could obtain information about lubricating this movement, and which areas to lubricate? I've had a hankering to start "tinkering" with the guts of these old watches, and this might be a suitable victim

    Thanks again!

    Thor

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  5. #4
    Member AbslomRob's Avatar
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    Re: Help with Gruen wristwatch

    I don't know that it would be a good idea to "start tinkering" with an automatic wristwatch w. Day and Date complications; you might want to start with a simple manual wind pocketwatch movement (you can get them of ebay for <$10) and work your way up. I tend to refer people to www.timezonewatchschool.com; for the money, the two courses are an excellent starting point, and the toolkits give you all the basic tools you need.
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  6. #5
    Member ThorBob's Avatar
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    Re: Help with Gruen wristwatch

    Point well taken, it does seem like jumping in at the deep end. Excellent tip on the school, I believe I will try out those courses; seems to be just what I was looking for!

    Thank you so much for your help!

    Thor

  7. #6
    Member lysanderxiii's Avatar
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    Re: Help with Gruen wristwatch

    There is a common misconception that "natural oil" is always whale oil. While whale oil was used prior to it banning in the 1970, natural petroleum based oil was far more common.

    "Natural" oil is generally petroleum based, although even today certain animal-based oils are use (but, not in any watch oils that I know of). Synthetic oil is not petroleum based, but manufactured from inorganic compounds.
    familiaritas parit contemptum; raritate admiratione wins.- Lucius Apuleius
    est necessry, accurate ad secundo? - Lysander magna
    iustum est horologium - Obscurus Genius

  8. #7
    Member AbslomRob's Avatar
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    Re: Help with Gruen wristwatch

    True; importing of whale oil was banned in 1972, but companies were allowed to deplete their existing stock. Whale oil was found to be quite useful for watch and clock lubrication in many parts of America and Canada due to its low-temperature properties. One of largest makers of whale and porpoise oil (Nye) sold their last barrels in 1978, and are still in business selling petroleum and synthetic oils for use with clocks and watches.
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  9. #8
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    Confused Re: Help with Gruen wristwatch

    I'm a little green at this (sorry to reply to a controversy with a question of my own):
    I have an old Gruen barrel style watch that has to be 70-plus years old from my dad that runs and would like to accurately determine its age. My readings tell me that Gruen practice was to etch caliber and style number, which together can determine a year of introduction, inside the case back. My problem: the case appears seamless! Would this be a sign of a unique specimen of some sort-- or would this watch open through the crystal?? I have an old Benrus that is so marked. Any advice is much appreciated. The last thing I want to go is undertake an operation that is high risk of damaging something that is working fine. How would a crystal be removed? / many thanks for any insight.
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    Last edited by thomachuck; August 30th, 2016 at 21:07.

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