Adventures with a Watchmakers Lathe - Part 1.

NOS Balance staffs for a size
16 watch - these for a Moeris
are particularly simple ones!

As with all pictures here click on
 the image for a larger view

There are a few watchmaking repairs that can only be done with a lathe and similar tools, the most critical being the manufacture of replacement balance staffs. Whilst replacement staffs are available from New Old Stock (NOS) for most watches by Waltham and several of the Swiss makers such as Cyma/Tavannes and Revue (that is one reason I deal in those makes) it is becoming increasingly hard to find them and prices are correspondingly rising, also NOS staffs are not available for any English watch made pre WWII.

For sometime I have been contemplating buying the necessary equipment and investing a considerable amount of time learning how to use it - several weeks full time I suspect before usable staffs are produced -  I haven't used a lathe since my apprenticeship days which was rather a long time ago and that lathe was about 6 foot long.

Having bitten the bullet and decided to do it I have finally managed to buy a second hand lathe and whilst I am closed for business awaiting the new financial year and for the supply of watches to pick up I will be writing a few blog entries to chart progress and to describe key aspects of the lathes use.

The first problem is the cost of a lathe, a new fairly comprehensive (but not complete!) set up by Bergeon, a premium supplier of quality watch and jewellers tools, is currently £27,594 (plus cutting tools and other bits and pieces) so that is clearly out of the question, even a "budget" watchmakers lathe by "Star" to a basic specification and with no motor is £2,874 and would require quite a few extras to make is usable for making staffs.


My Pultra 10 Lathe after
a days worth of restoration.

So clearly second hand was the way to go, after several failed attempts I was very fortunate to acquire an excellent English lathe by Pultra probably made in the early 1950s and with a very good specification. I was particularly fortunate in that some one tried to "snipe" me with a bid in the last 10 seconds of the eBay auction and I won by 12 pence!

A couple of the collet chucks (more of which in a later post) need replacing at between £20 and £45 each new (depending on size) or £10 - £15 used and I may want a few more, but apart from that it has all of the pieces necessary, except a motor which the seller has yet to auction.

However I have decided to go with a new electronically controlled motor which is on order, it is not designed for this type of lathe so will need some work to mount it and the lathe onto a base board and to connect them up.

One interesting feature of watchmaking lathes in general is that they are operated very much like a wood turners lathe with the cutting tool hand held, this close up shows the tool rest (not in position in the picture - in use it would be closer to the centre line). This particular one is a premium "tip over" type which can be folded back to allow access to the work for measuring etc. and then tipped forward, back into position without having to reset its position.

The whole lathe is 10.5 inches long and the tool rest only an inch long so this is pretty small precision engineering!

It was missing a few, mainly non essential but nice to have things, most of which I have now sourced and hopefully they will all be here in a week or so.

So far the total cost is about £1.2k but small compared to £28k for a Bergeon!

Click on "Lathes" under labels to the right of the page for other articles in the series.

Restoring a Silver Watch Case

Click on the images to see a larger
version.

A while ago I posted a description of how a watch movement is cleaned, in this post I explain how I restore a silver watch case. The case in question was made by John Woodman of Smith St, Northampton Square, London in 1888.

From the wear pattern you may be able to see that the back of the case is depressed, there is also a dink bottom left and there is a lot of pocket wear, in reality it actually looks worse than in the picture. So something had to be done.

The first stage is to get rid of the worst of the muck and oxidisation, this is done with silver polish and a glass fibre brush.

If this were not done the next stage would not work as effectively and the fluid would have to be changed more frequently, perhaps after each case.

The ultrasonic cleaning is primarily to get into the parts other processes cannot reach including into digs and scratches. The fluid bath is detergent based and the case will stay in for 30 minutes which seems about optimal for a silver case.

The second ultrasonic machine shown is loaded with a solvent based cleaner that I use for cleaning movements.

The next stage is to press, rub or hammer out the back and the dents. This process will be different depending on the way the case is made and any finish such as engine turning on the back. Swiss cases in particular are sometimes made with a bezel similar to that on the front with a silver disk inserted - if you press on that to hard it will come out and be a devil to get back in and it you hammered the edge probably impossible.

It is better to press or rub rather than hammer as it will cause less damage to the inside which is difficult to burnish out due to the shape of the case and the necessity of preserving the hallmarks. The amount of work done on the outside has therefore to be balanced with the amount of damage to the inside and possible distortion of the case which may or may not be readily correctable.

The picture above shows the case after this work, the dink still visible but it is now more of a scratch or dirty mark.

For a case with a smooth back now comes burnishing with increasingly finer abrasives. A balance has to be struck between the amount of silver removed compared to the gain achieved in appearance and possible loss of structural strength.

In general I do not try and take out all of the marks but to still give a nice finish. All of this is done by hand.

Ten Louis Brandt and Frère - Omega & Labrador watches.

In the last couple of months I have been able to buy in more "Omega's" than I normally would expect to get in a year, here are most of them, 2 at Brackley missed the group shot. They vary in size from approximately English size 10 to a rare size 18. 

They date from 1897 through to 1922 and all are essentially the classic François Chevillat 1894 designed Omega movement and have 15 jewels with a Breguet sprung cut compensating balance with double roller.

Two from 1900 are unusual in that they carry the Omega name or Logo but have screw mounted jewels on the top plate and a screw micro regulator and are therefore the higher grade Labrador in all but name, but this is before LB&F changed the company name to Omega.



 

The Safety Pinion (Fogg's patent)

A Reversing Pinion prior to assembly.

The Safety Pinion originated in 1865 when it was usually described as "Fogg's patent", it was intended to avoid damage to the movement in the event of a mainspring breakage, the spring being let down too quickly during maintenance or following failure of the click (ratchet stopping the mainspring arbor from "winding down" and forcing the barrel to move instead).

The problem was that with the very strong springs required at the time the backlash after a failure would go through the train and potentially break weaker parts, mainly I suspect the lever pallet and pallet jewels.

The solution is quite ingenious. Instead of the centre wheel pinion being fixed to the wheel / staff it is screwed on. In normal use the gear teeth on the mainspring barrel bear against the pinion and keep it screwed down.

A "Reversing Pinion" during assembly
but not yet screwed on.

If the pressure is suddenly reversed the pinion unscrews and no reverse power is applied to the rest of the movement.
This solution was initial used by Waltham and then by Elgin who presumably licenced it, but by the 1890's, if not earlier, the concept was more widely used in the USA (the example shown is from a Seth Thomas of 1896) and by a number of the larger makers in England including The Lancashire Watch Company and William Ehrhardt.

Waltham later introduced the "Safety Barrel" to address the same problem but as the amount of power a watch required reduce with the introduction of lighter movements, improved manufacturing tolerances and more jewelling, there was no longer a real need and safety pinions were discontinued.

Slow train, fast train

No not about railroad watches as such but about the frequency at which a watch balance turns. By the middle of the 19th century lever watches were pretty much standardised at 16,200 vibrations per hour (VPH). As watches got smaller and engineering tolerances got tighter makers started to move towards a faster beat of 18,000 VPH, usually referred to as a "Quick Train".

As usual the Americans moved first with Waltham changing the beat of their size 18 full plate 1877 model to 18,000 after launching it at 16,200 and the Illinois Watch Company changed quickly in about 1879.

The conservative English trade were, as usual, quite a way behind probably not helped by the investment required in redesigning their watches to change the gearing in the train and retooling costs which would have been more significant for the much smaller English companies than for the large American operations.

Generally it was the early 1890's before the Coventry and Lancashire trades started to use the faster train, led not unnaturally by newly introduced keyless three-quarter plate designs with some of the older full plate designs being allowed to die a natural death, particular Fusee movements,  and others being changed mid life or when Swiss Lever escapements started to replace the English Lever.

The London trade were even more conservative with some makers, notably P & A Guye and J.W. Benson persisting with the slower train up until around about the first World War. The lovely Benson Ludgate pictured was made in 1912 still running at 16,200 which does give it a very nice "majestic" tick.

Wrist watches, as one might expect, continued the development and my 1980s Rolex runs at 19,800 VPH with later ones running even faster.

Waltham Display Case

Click on the image for a larger view

As described in some detail in my post "the standard watch case" buyers could at some retail outlets configure their own watch by selecting a case, movement, dial etc. and then to have the watch assembled for them on the premises

The Waltham display cases as shown here could be used to display a selection of movements to help the customer decide. I suspect the hole in the base was used to bolt it down to stop people making off with a potentially valuable movement.

Now this type of case can be used to simply display the movement or to use it as a desk watch.

Click on the image for a larger view

The back of the case has a second crystal so that the movement, in this case a 17 jewel Waltham 1908 P.S. Bartlett from 1918, is visible.

A Double Own Label!

A 16J Errington, 1895.

At first sight this appeared to be a normal "own label" watch made for by C.H. Errington of Coventry for Curtis & Horespool of Leicester.

However looking at the hallmarks there are normal marks for Chester 1895 but one set of makers marks have been over-stamped by another.

Under high magnification and with a hint from another mark (see below) it is possible to read the second set of marks as belonging to Alfred Moss Jacobs & Co (Watch Makers), 18 Cross St, Hatton Garden, London.

The original marks are probably those of Errington.