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PeterS

Cleaning and lubricating jewels - Derby 40

Question

I picked up a movement from Ebay to tinker with, I think it’s Derby 40. I only have experience with incabloc and this one puzzles me. There is a balance jewel and an endstone but no shock spring so why the endstone?
To clean and lubricate the jewel it looks like I’m going to have to remove the hairspring.
Any tips, threads, articles or videos lubricating this?

20190612_213743 (Copy).jpg

20190613_212249 (Copy).jpg

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Open "boot" on index pins. Loosen stud screw. Remove balance. Remove two screws on underside of balance cock to remove cap jewel.

Oil drop should cover around 50% of the cap jewel. Refer to BHI document.

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Thank you for your tips and explanations.

I don’t know how you open the boot. My plan was to loosen the stud screw and slide the hair spring through the boot and index pin to remove it but looking at the picture the hairspring doesn’t go as far as the stud. I’ll have to have a good look at it at home, admittedly I never took a balance apart and I’m not sure how it is actually attached and I can’t see it that well from the picture.

Is the BHI document available to view anywhere?

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Hi peter, Drop the balance with hairspring attached into a jar of lighter fluid let soak for couple of days. Put some penetrating oil on the two little screws let sit over night.

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5 hours ago, Nucejoe said:

This looks funny, my msg gets posted after you have already done removed the screws. :o

Apologies.

That’s an odd one. I know websites can be ‘cached’ in web browsers but never came across it on forums. Perhaps the moderators would know what could be causing the lag.

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Lighter fluid contains traces of oil so it would need to go in a fluid that has been formulated for watch cleaning afterwards to remove the traces of oil.
What kind of penetrating oil do you use on stubborn screws? A bottle of it would be handy should I need it.

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A soak in diesel fuel, naphta for day or two,  ends the old story of heads popping off the screws.

I remove balance cock pallets and soak the rest, give one dip in a fluid I can stand the odor of.

Any cheap multipurpose oil would do.

I use several solutions, detergent seperately and brush extesively.

 

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