Bulova 17AH 15 Jewel Swiss ADJUSTED

Hi

I bought a very nice Bulova pocket watch. The movement marking is stamped '47'. I believe this means the watch is from 1947.

Having looked a a number of similiar watches, this is the only one that I have seen with ADJUSTED.

How does this set it apart from similiar watches like this?

Thanks,

cole

Reverend Rob's picture
Reverend Rob
Posted February 27, 2018 - 1:50am

Panel Member

Unadjusted watches were not subject to tariffs or possibly fewer tariffs at different times in the history of the company. The oldest pocket watches usually had '5 adjustments' or some number associated with the adjustments. This should not be confused with adjustments in positions. Watches marked "Adjusted to (x) positions" are not the same thing. 5 or even 6 positions means chronometer spec usually, while unspecified adjustments could mean almost anything. In general, it refers to regulation and adjustments to endshake in the jewels. 

Watches that were imported into the US will bear the Bulova import code 'BXW'. I'm not sure what year this started, as the older watches do not have the code. Tariffs were also levied against completed or finished goods, and an ebauche is not a finished product. Bulova would complete assembly in the US, oftentimes fitting Bulova custom balances, among other things. In some cases, Bulova was importing from itself, as it did own factories in Switzerland. 

I suspect the laws and tariffs changed often. Watches produced entirely in the US have no import code of course.  This watch was produced in the years following the Second World War, and may not have needed any import code and may not have had any tariffs imposed. I'm just speculating, here but one thing we do know is that the circumstances and regs regarding importation changed over the years. 

 

 

coler
Posted February 27, 2018 - 12:03pm

Thank you very much. I would have never known this. I thought 'stamps' ADJUSTED / UNADJUSTED referenced the actual position adjustment of the watch. Very interesting.

cr

Reverend Rob's picture
Reverend Rob
Posted February 27, 2018 - 12:59pm

Panel Member

Complete watches are always adjusted prior to sale, or distribution. The minimum adjustments would be rate and beat error, and from there it would have been tested in a minimum of two positions. Three positions is average. Positional errors are caused by many things, not the least of which is the poising of the balance. A balance that is unpoised will have a heavy spot, like the tire or rim on a car. This means it will have a vertical positional error, that is, when the watch is crown up or down or left or right. Even miniscule variations have a large effect. 

Hairsprings are adjusted, jewel height can be adjusted, there are adjustments also for heat and cold. A chronometer must be tested in 5 positions and heat and cold. 

In the  past, even the pallet fork could be poised. Adjustments to the pallet fork include endshake as well as depth of the entry and exit stones. A beat error is when the balance is not centred, and will swing further one way as opposed to the opposite. At rest, the balance must be centred and the impulse pin in the centre of the pallet fork horns will locate the pallet fork in the centre of its travel also. Watches with movable stud carriers can be adjusted for beat error easily, by rotating the position of the balance. Errors will also occur when the hairspring passes through the centre of the regulating pins. Ideally, in a well adjusted watch, the hairspring passes through the dead centre of the regulating pins, and this adjustment is done with a microscope for chronometers. The distance between the pins also plays a huge part in the delta, or difference in rate in varying positions. When the hairspring is not touching either regulating pin, it is accessing its entire length, which is overlong. The theoretical length of the hairspring is shortened when it touches either of the regulating pins. Closing the pins decreases the amount of time that the hairspring is longest, and is adjusted accordingly for the type of positional errors encountered. 

These times are miniscule, and beat errors are measured in milliseconds. 

The subject watch has no movable stud carrier, and so must be adjusted by removing the balance from the bridge, and turning the hairspring collett with a special tool. It is a bit of a hit and miss procedure, because you won't know if you are correct until you reassemble the balance to the bridge, and test the watch running. 

The balance also has no shock protection, so broken staffs are more common.