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Khan

EB 8021 N service

Question

Dear watch enthusiasts 

As a hobbyist, I'd like to ask few questions for EB 8021 N.  

Where do you release the mainspring?

Do I have to remove the barrel Arbor when replacing the mainspring? The Arbor seem to be fixed with the barrel. 

These EB movements are way more trickier compared to any higher quality swiss movements. 

Thanks in advance

Khan

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That sounds similar to an EB 8810 The arbor forms part of the lid. I had to tighten the mainspring end on the arbor before fitting and wound the spring in by hand to the barrel and lastly rotated the lid the final few turns with the hook tight on the arbor.
Wasn’t easy. Not sure how that mainspring is let down the layout was simple on the Eb 8810 held in place by a clamp.



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That's tough, have tried that in case the mainspring was stuck on the Arbor. The EB 8810 has the click for releasing mainspring on the top. In case of EB 8021 N, it's hidden in lowest part and covered with top plate above barrel. Question is now, how to remove the Arbor and winding disc to securely place the mainspring, please find my images. 

IMG_20190414_134354693.jpg

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I serviced one of these about a couple of week ago. I found the ratchet wheel (which is what it is) was friction fitted to the barrel arbor. With some careful encouragement with 120 screwdriver, turning the driver as I rotated the barrel, the wheel popped off. Of course, once off, the arbor was freed from the barrel. Refitting was done using brass tweezers, again rotating while pushing down (not much force required). The servicing went relatively well and the watch is now winds perfectly and is ticking away happily!

Hope that helps?


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Hello Adam
I will give it a try. Thank You very much for advice. And do You have an idea how to release the spring force when fully winded?
Kind regards
 

You would need to remove the calendar mechanism to reveal the click. I’ve added a photo again showing the brass plate removed. You can then release the mainspring tension using the crown as normal.55145b4508cb5139adc7daf28c9103c5.jpg


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Amazing responses! I appreciate your time and effort. I also demounted the Arbor by placing two screwdrivers right below the Arbor on the spring side it popped out. Regarding spring force release, I removed the balance and pallet fork and 'slowly' let the wheels run by controlling with a pegwood (hope it doesn't give wear and tear)..

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Sounds resourceful. I’ve resorted to similar inventive methods in the past. To be honest, it’s probably unlikely the soft pegwood would have caused damage. It will just need a thorough clean.


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Possibly. If it unwound uncontrolled then more likely. Inspect the pivots and jewel holes under high magnification to check before reassembly.


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Hello Adam

Would You kindly explain the assembly procedure for the barrel Arbor and the mounting of the barrel disc on the opposite side? After replacing the new mainspring, it seems tough and impossible to push the Arbor in the center..

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