Service: Stowa B Uhr / calibre Unitas 2812.

IMG_7531Anders has sent us this impressive B-Uhr for a service.



IMG_7535The movement is beautifully decorated with Cote de Geneve on all the bridges and perlage on the base plate.IMG_7536Performance is not to bad, but letting a watch run in this kind of dirt will wear the movement down.IMG_7550I remove the movement from the front of the case.IMG_7551I remove the hands one by one as they are so large.IMG_7552The dial removed shows more nice perlage decoration on the dial side of the base plate. Almost unbelievable to think this was military equipment.IMG_7554I have removed the central seconds cock, pinion and the intermediate wheel that is pressed on the pivot of the third wheel and engages with the seconds pinion.IMG_7557Here you can see the hacking lever mechanism.IMG_7565Here you can see how dirty the movement really is.IMG_7567Here you can see the remains of old oil that has solidified, this stuff is too tough for the cleaning machine to remove.IMG_7568The solution is some good old pegwood to clean the jewel.IMG_7569Here you can see I have removed the barrel bridge.IMG_7571I now remove the setting mechanism.IMG_7573I will reuse the old mainspring after cleaning it, as it is still good.IMG_7616The movement fully taken apart and cleaned.IMG_7618The mainspring is clean and back in the barrel.IMG_7619I have put the barrel back in place together with the barrel bridge.IMG_7621Now the bridge for the centre wheel and third wheel is in place.IMG_7620I fit the winding mechanism into place. I have also put the cap jewels for the escape wheel and balance back in place.IMG_7622A nice feature is that both the forth wheel and escape wheel have separate cocks.IMG_7630Now the movement is back together and ticking as it should.IMG_7624Dial Up.IMG_7625Crown up.IMG_7626Crown Right.IMG_7627Crown LeftIMG_7628Crown downIMG_7629Dial down.IMG_7631The movement is ready for the dial.IMG_7632The Luminous compound on the hands is falling apart and on the minute hand you can see a large crack along the middle.IMG_7633We agree with Anders that the best way to preserve the hands is to apply a thin layer of new compound on the back of the hands. This prevents the compound from falling apart and is not visible to the naked eye.IMG_7639Here the movement goes back in the case with dial and hands in place.IMG_7635This movement looks as good as it performs.IMG_7636I have got to say even though I’m not a huge fan of military watches, I love the functional look of this watch. Andres wanted to keep the watch as original as possible and decided to keep the old crystal.IMG_7634The case back has properly stamped military markings.IMG_7638With approval from Anders here is a wrist shot to truly sow the dimensions of this beast!

20 thoughts on “Service: Stowa B Uhr / calibre Unitas 2812.

  1. Hello. I’ve lost my stop- second levers. Can you show them and their dimensions? You might have to make yourself.

  2. Hi,
    I’m thinking of getting one that has come up for sale near me! It’s in very good condition, still has the original Strap!! What’s a good price for one in all original condition?



  3. Pingback: I think you guys should check this out: Service: "Stowa B Uhr / calibre Unitas 2812"

  4. Great post Mitka! I’ve always wanted to have a look inside one of those beasts. Great solution (IMO) for the hands.

    Btw, that blue nato strap does not really fit … ! 😉

  5. Pingback: Interesting read?

    • All the original B-uhr navigation watches was 55mm.
      IWC, A. Lange & Sohne, Laco, Wempe and Stowa was the only suppliers. Exterior is next to identical.
      The Stowa has perhaps the most beautiful movement.

  6. The movement is in nice condition and excellent time keeping in six positions for a watch that must be 70 odd years old. Shame about the crazed crystal, be careful it doesn’t fall out. Nice work Mitka.

    • The crystal is safe.
      And it looks much nicer in real life and natural daylight.
      I had to decide whether to replace it or not.
      As it may be the 70 year old original I decided to leave it.
      I can replace it easily later on if I regret the decision.

  7. Sitting with it in hands right now…. The size is enormous! It makes my classic Speedmaster look like a little ladies watch in comparison. 🙂
    Not a daily wearer for sure, but a unique piece of horological history.
    Thanks Mitka!

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