A Bluffers Guide to Watch "Bushing"

Three typical Watch bushes.

Where a steel pivot runs in a brass hole in the movement there will eventually be some enlargement of the hole, often turning it into an oval due to unequal pressure on it.

Occasionally there will be some wear to the pivot as well in which case the pivot will need to be smoothed and reduced in size which will result in it being loose in the hole.

Problems are most common on the fast moving and quite small 4th (Seconds) wheel and on the bottom pivot of the centre wheel which although it moves slowly it has a lot of pressure on it and can't be effectively oiled without taking the movement apart - so it seldom gets done.

To remedy this situation a brass Bush or "Bouchon" is set into the movement.

Part of my collection of Bushes, the two large ones bottom left are for
clocks, those for watches in the top box have an external diameter from
0.8mm to 3mm with a range of hole sizes and depths. These are New
Old Stock, the top set is still available but at £270 the set (120 pieces)

First the original hole has to be opened up to accommodate the size of bush required using progressively larger reamers in the Staking or Jewelling set, this will keep the centre of the hole in the right place.

The bush has to be a friction fit but not so tight that excessive force is required to push it in or the bush could be damaged or the movement distorted.

The reamer on the centre hole of a scrapped bottom plate. The metal is soft and the
tool very sharp so it is just turned by hand with no significant leverage required.

If necessary, which it usually is on the bottom plate, the bush has to be ground down to the same thickness as the plate, on the top plate the shaped end of the bush is left as it looks similar to normal pivot holes and helps with oiling. The bush is then pressed in using the staking set.

My staking set with leaver operation, a different anvil than this would
probably be used when pressing home a bush.

The result will be as efficient as the original.

A re-bushed centre wheel pivot hole that I did recently.

Although more expensive, sometimes a jewel will be used instead of a bush resulting in a higher jewel count than advertised:

This Waltham Traveler has been turned into a 15 jewel watch although I suspect
that was because someone wanted to do it rather than to correct a problem.

On occasion you may find the reverse with a broken jewel replaced with a bush, on the centre wheel this is very unlikely to cause any performance issues - European makers did not like putting jewels on the centre wheel in any case as they add little - except for appearance and marketing - and are susceptible to damage.

Bushes used to replace jewels at the 4th wheel and below will not be as efficient as a jewel and will be more prone to wear in the very long term.

A high grade Keystone Howard Series 5 with the top centre jewel replaced
with a bush. The original jewel was machine set and it was probably thought
that enlarging the hole to replace with a friction fit jewel would have left
the bridge dangerously weak. The brass bush however retains its structural
integrity. There is no noticeable increase in friction and the problem was finding
a mainspring that would not overdrive the movement rather than needing more power.
 

J.W. Benson's Alpha-Numeric Serial Numbers.

J.W. Benson "Bank" watch, 11J, 1922
The case has the same numeric serial number as the movement so the date is pretty certain.

Some Benson "Bank" movements and its derivatives after c 1901 have a serial number prefixed with a letter.  About 12% of the 59 Benson "Bank" watches I have seen have this numbering system but the percentage would be somewhat higher if only watches after 1900 were considered.

Serial number L4381 on the top plate of the 1922 movement shown above.

Some have speculated that this is a date code but I have been unable to find a good correlation.

Things get more confusing if you take off the dial because the serial number prefix on the face plate is always different to that on the top plate.

Serial Number C4381 on the face plate of the 1922 movement shown above.

If the Letter was a date code it would imply that the face plate was made 9 years before the top plate or before the watch was finished which appears unlikely.

Unusually for Benson those movements with an Alphabetic prefix to the serial number often have the same serial number on the case as on the movement but without the prefix which makes the dating certain (unless the watches were re-cased by the maker).

The silver case, hallmarked for J.W. Benson 1922 serial No 4381.

So together with the lack of correlation between the letter and dates it appears the letter represented something else.

But I have no idea what.

The watch from the front.

J.W. Benson, 19J, 1904.



J.W. Benson 1904.

This is a very rare, perhaps unique, watch and it perplexes me.



The inside of the Benson 19J movement showing the Geneva stop work
on top of the barrel and the English Lever escapement.

It is a high grade London made size 18 movement with 19 jewels, a Breguet hairspring, gold balance screws and Geneva stop work. And I suspect it is a Half Chronometer (adjusted) movement.

 
But it is branded the "Bank" watch.
 



A Benson "Bank?" from 1904 but with 19 Jewels, a Breguet sprung
cut compensating balance with gold screws and Geneva stop work.

It has the same frame and design as the normal "Bank" watch of the period but I have records for 59 other "Bank" watches in various sizes, in silver and gold and in Hunter and open faced configurations (and I have seen pictures of an awful lot more). None have Geneva stop work and all have 9 or 11 jewels with an over-sprung rather than Breguet sprung balance - which is in accordance with the literature and my Benson catalogue from the 1930s.




A typical Benson "Bank" with 11 jewels from 1920. This is a later version with 4
plate screws rather than the earlier 3 and a slightly different layout of the train.

From the Benson adverts I have seen it was their normal practice to give names to most of their watches, but only the "Bank", "Ludgate" and "Field" had the name inscribed on the movement, others such as their high end "presentation grades" - the "Heirloom", the "Superlative" etc. are simply marked "Best London Make" or similar and with the Benson name, address etc.

The Benson "Superlative" from c 1903, probably an upgraded "Field" and still
in my Catalogue from c1936 then costing 70 Gns as a Gold Hunter or Half
Hunter in it's standard size and £100 as a large (2.5") Hunter.

I can’t understand why Benson would have branded a very high grade watch with the name of what at the time was their entry level London made watch.
 



A "Bank" type watch but with 15J for Sir John Bennett 1893, almost
certainly by P & A Guye.

My best guess is that this was an expensive mistake by the engraving department at  P & A Guye who made a lot of watches for Benson, including almost certainly the "Bank", but who also made variants of the same movement in various grade for Benson and the trade.
 

The earlier version of the "Bank" watch made into the early 20th Century.
Those from the early 1890s had 9 jewels, later increased to 11. The two
plate designs were probably made in parallel for 10 - 12 years. This design
appears to have been unique to the Benson branded "Bank", those sold into
the trade, and some sold by Benson, having the plate design of the later "Bank".

 

Waltham 1908-642

Waltham 1908-642 from 1918.

This is one of a series of posts illustrating the main grades of Waltham size 16 watches, primarily the 1899 & 1908 models.

A fairly rare movement with only 3,000 made in two runs, as an intermediate grade between the -640 and -645, it appears to be a 1908-640 but adjusted to 5 positions rather than 3 and without some of the decoration of the -645. The two runs were mixed Lever Set Railroad watches and Pendant Set Railroad Grade. I have had 3 of these, all pendant set and it is possible that the Pendant set versions were for the UK where Lever Set watches were not popular.

The 17 jewel movement is also adjusted for temperature and possibly isochronism, it has a Swiss lever escapement with a steel escape, Breguet sprung cut compensating balance, double roller and screw micro adjustment.

WD40 - The watch's enemy.

click on the image for a larger view

Not for the first time I have had a watch in sprayed with WD40, you can't mistake that smell.

The watch has a 15 jewel Ehrhardt movement - probably a 1906 series but I have yet to take the dial off - it was made for the British Military during WWI  (note the broad arrow property mark below the serial number) but was one of many made by the company that were never delivered and then put into silver cases and sold to the public, this one hallmarked by Ehrhardt in 1921.

It was advertised as "in very good condition and working" and "the watch will run the full length of its wind but does run slow I think it needs a service, the watch sum [sic] time stops I shake it and it starts again".

To get it going someone (possibly not the vendor but I would not bet on that) had sprayed it with the dreaded WD40, it may have run for a short time but on arrival only ran with pressure and it is easy to see why when you look at the hairspring, several coils of which are stuck together. And the stuff will have got all over the place causing other problems.

It should be restorable but will take longer than it should.

WD40 is great stuff - but not on watches!