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AndyHull

Brac Cal 107 balance jewel.

Question

I picked up a Brac Cal 107 "Tropicalized" watch a while back, with what appeared to simply be a broken balance top pivot. I removed the balance and examined the pivots and sure enough the top one was missing.

However I purchased what I assumed was the correct part namely a "Balance Wheel Assembly BRAC Cal. 107 (10.5''') Part #705 (TC125)" - and attempted to fit it.

This was a little more fiddly than fitting a "balance complete", but since I couldn't source one of those, I pulled the trigger on the balance assembly, and fitted it to the existing balance cock without too much swearing.

However it appears to my untrained eye that there is a second issue, namely that the lower jewel is too low. The balance therefore doesn't sit correctly. I imagine this may have been pushed down by the same impact that broke the top pivot (and made the interesting impact mark in the bottom plate, which you can see in the picture.

So the questions (based on this admittedly pretty poor picture) are.

A) Is my diagnosis likely to be correct?

B ) How to I remedy this ?

 

RIMG0281.JPG

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I have read enough of your posts to think you have made a well reasoned call.I would try pressing it back through from the opposite side with a little oil and the flat of a screw driver.flush as previously mentioned.

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2 hours ago, JBerry said:

Do you have a jeweling tool to adjust the height of the jewel? I would think it should be flush with the mainplate

I don't have a jeweling tool, unfortunately, but... I suspect that might be next on my list of things to buy.

The jewel certainly looks to be well below the level of the main plate, but I wasn't sure if that was normal for this type of movement, and my new balance staff was too short, or if my hunch was correct and the jewel had shifted.

I guess I should strip the thing down, or at least pop off the dial and hands,  and examine it from the other side, but that may not prove conclusive.

Better still I should compare with another Brac 107, but since they seem to be fairly uncommon, that is easier said than done. 

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All these movements work in similar ways..I don't think they reinvented the wheel when they built this one.it doesn't makes sense for the jewel to be recessed.you would have metal on metal friction.don't you think?

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1 minute ago, yankeedog said:

I have read enough of your posts to think you have made a well reasoned call.I would try pressing it back through from the opposite side with a little oil and the flat of a screw driver.flush as previously mentioned.

I guess I have little to loose, since the watch wasn't expensive, but I like the look of the thing, so I didn't want to dive in and break the jewel.


Perhaps a little gentle pressure, and go easy with the sledge hammer, and we should be good to go.

I've put it back in the to-do pile, so when it reaches the top again I'll give it a go. I guess the worst that can happen is I have to source some jewels and learn how to do it properly. :lol:

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Just now, yankeedog said:

All these movements work in similar ways..I don't think they reinvented the wheel when they built this one.it doesn't makes sense for the jewel to be recessed.you would have metal on metal friction.don't you think?

Actually you make a good point there. I think you have convinced me. I'll give it a whirl. I promise not to use too many sweary words when I inevitably break something important. :P

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I stripdown to mainplate and cock to push the jewel back in by a wooden stick and  adjust for the proper position of balance staff, all as the proceedure to fit in a new balance staff or readjustment of a worn pivot.

Pin pallet offers a wide range for fork and escape interface, whilst jeweled pallets don,t, therefore jewels should be routinely adjusted for proper interfaces.

I beleive I have brac 107 parts, will check and infrom you, be happy to send all parts you may come to need. 

The new wheel and old hairspring are to be vibrated together.

Regards.

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1 hour ago, AndyHull said:

Actually you make a good point there. I think you have convinced me. I'll give it a whirl. I promise not to use too many sweary words when I inevitably break something important. :P

At a young age my father explained that swear words were actually incantations passed down to us from the druids ,they were only outlawed by the church because they worked. I suggest waiting until the full moon to adjust the stone.Or out of an abundance of caution until the autumnal equinox.

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5 hours ago, Nucejoe said:

Found brac107,  drop me your address with the list of parts you need.

Best wishes

Thanks, I will do.
I may not need anything, apart from confirmation that the jewel should be flush with the main plate, but I suspect it should.
Other than that, I think I have everything, although I can't obviously be certain till I tear it down and fix it.
That may not happen for a few days, as the weekend looks pretty busy at the moment.

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52 minutes ago, AndyHull said:

Thanks, I will do.
I may not need anything, apart from confirmation that the jewel should be flush with the main plate, but I suspect it should.
Other than that, I think I have everything, although I can't obviously be certain till I tear it down and fix it.
That may not happen for a few days, as the weekend looks pretty busy at the moment.

It dosn,t have to be perfectly flush, actually it sits a bit in, 5% mm, the determining factor is to get a functioning  impulse pin/ fork horn interface and balance wheel not rubbing on parts which it is not suppose to.

I have enough brac parts to be your material house for life.  :lol:   No problem attt all.

Regards 

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