Beautiful Minerva has staff issues

[Dmitry]

Hello Team,

salvaged a beautiful Bulova Minerva (ca 1920) with a rare BII movement. In my bargain hunting on ebay I managed to secure three different movements in various conditions of delapidation, but enough to put together one working movement.

Interestingly, although all the calibers are marked as BII, they are not quite the same:

1. The hole for the stem to go in is different, I had to drill a larger diameter hole in #1 to accommodate a stem from #2.

2. Balance cock posts in #3 are thicker than in #1 to the point that it will simply not fit.

But these details are all nice and dandy and make the restoration journey that much more enjoyable and memorable, what fun would that be to just put the parts together.

And this brings me to the subject of a broken staff, see picture attached.

I lucked out with two movements where staffs seem to be OK, but while on #1 it functions perfectly (15sec a day deviation), on #2 the wheel just would not turn.

I have attached macro pictures for you to examine and I am looking for advise on technical details for the staff, I was not able to source any details on what type of staff I need to order for the B2, or what else I should check beyond the obvious inspections of the top and bottom jewels, which seem to be OK as well. (Only staff on #3- pictured- is broken, the #2 which appears fine would not turn.)

What confuses me is that even when I remove the pallet fork to test out the balance wheel assembly, I get no back and forth movement, the wheel does not wobble, but instead appears being held in place by some other majic powers.

I will appreciate any insights into what kind of saurcery I should try next.

[jdrichard]

8 hours ago, Dmitry said:

Hello Team,

salvaged a beautiful Bulova Minerva (ca 1920) with a rare BII movement. In my bargain hunting on ebay I managed to secure three different movements in various conditions of delapidation, but enough to put together one working movement.

Interestingly, although all the calibers are marked as BII, they are not quite the same:

1. The hole for the stem to go in is different, I had to drill a larger diameter hole in #1 to accommodate a stem from #2.

2. Balance cock posts in #3 are thicker than in #1 to the point that it will simply not fit.

But these details are all nice and dandy and make the restoration journey that much more enjoyable and memorable, what fun would that be to just put the parts together.

And this brings me to the subject of a broken staff, see picture attached.

I lucked out with two movements where staffs seem to be OK, but while on #1 it functions perfectly (15sec a day deviation), on #2 the wheel just would not turn.

I have attached macro pictures for you to examine and I am looking for advise on technical details for the staff, I was not able to source any details on what type of staff I need to order for the B2, or what else I should check beyond the obvious inspections of the top and bottom jewels, which seem to be OK as well. (Only staff on #3- pictured- is broken, the #2 which appears fine would not turn.)

What confuses me is that even when I remove the pallet fork to test out the balance wheel assembly, I get no back and forth movement, the wheel does not wobble, but instead appears being held in place by some other majic powers.

I will appreciate any insights into what kind of saurcery I should try next.

End play off

[oldhippy]

Have you checked to see if any have a shockproof, only the one you have posted doesn't. The staffs will be different. Buying old watch movements who knows what you have it's more likely you have cannibalised movements. I can tell be the condition of the screws that movement has had very poor treatment.  

[Nucejoe]

 End stones might be pushing on pivots of the staff, in which case balance should get free to oscilate when you loosen cock screw.

That is what jdrichrad reffering to by end play.

Regs

 

[HectorLooi]

if you look at photo #2, the upper pivot is broken. I would check the upper jewel for damage too.