Tuesday, December 1, 2020

Apprentices corner

Think of a balance wheel like the heart of a watch. The pivots and the staff are the main arteries, the hairspring is the muscles expanding and contracting. Without the arteries, there is no movement, no rotation, and no watch ticking. The biggest culprit of damage: impact.                         
In the above image you can see the fine pivot extending at the bottom of the staff, however the top pivot has been broken off. This short length does not fit into the upper jewel and thus the balance wheel has no top point of support. Broken balance staff pivots are a common problem amongst older watches and is the reason for replacement. You will also see the coil of the hairspring where it slots into the balance cock. This style of spring is called a Breguet overcoil. 

Below you can see the image of six balance staffs, with the left-most being the brand new replacement balance staff and the five on the right are the various broken staffs removed from the Japanese railway pocket watches we have been working on last week.
Up until the mid-1960s, shock absorbers such as Incabloc and other patented inventions were not common in pocket watches, and as a result, many watches now lay dead in boxes or storage or the back of your cupboards collecting dust. These shock absorbing systems were the 'bike helmets' for the balance staff pivots when encountering a not so soft landing with the floor, preventing the pivots from snapping. Hence, earlier watches when encountering these circumstances, were not so lucky. Whilst it remained easy to break a pivot on the balance staff, replacing one is a skill not so easily found; as not all watchmakers are able, or have experienced how, to replace a balance staff. There is no room for error and no place to hide at any step of the process. No corners are to be cut or else the final result will be worse than the before. Patience and true attention to detail are the cornerstones. Without these, the job cannot be even mildly considered.

Now to begin the written recount of the journey through the replacement process.
The process, after removal of hairspring, begins with the correct selection of tools; our balance staffs all belonged to the same calibre, with identical dimensions, we needed only to select the correct tools once and then note the numbers of the tools down. Continuing on, the tool is then lowered into place just over the pivot on the shoulder of the staff, and checked for alignment. This is all before our second most important part of the process comes into play: the right force. A small hammer strikes the tool at the top to push down on the staff and subsequently push it and the balance wheel out of the roller. The initial moment before you strike can only be described by the feeling of diving into a body of water and the suspense between your feet leaving solid ground and the re-entry into the water. A moment of truth, one could say. The first hit over, you now have the feel of the staff and can adjust your force accordingly, whilst also listening for changes in tone. Once out, all excitement is held until the roller and roller jewel are assessed, along with the balance wheel. Once all is revealed well, it is time to double down to remove the staff carefully from the wheel.

This stage has two schools of thought. Either, one strike to cleanly remove the staff, or a series of small nuanced taps to encourage the staff to move through the rivet. The second is the preferred, for smaller taps allow the metal to freely loosen, provided there is adequate wheel support, without high risks of shredding the rivet and opening the hole for the next staff too far. We experienced this with one balance staff hole, and despite many adjustments, the wheel remains ever so slightly wobbly. Enough to annoy or discourage our efforts, but not enough that the watch does not work within its means. The inability to hide is the perfect way to describe our triumph, not through lack of effort to correct, but there comes a time where you must weigh the risks and draw the line. This first stage cannot be rushed or sloppily completed or else the next stage will not end well for the watch or the maker.

The new replacement staff must be tested between the main plate and balance cock for N shake and rotation. Satisfied, the new staff can be supported from underneath as two newly selected tools come into play. The riveting stage begins with a flat tool that simply presses the wheel down by hand onto the staff so it sits flush with the widest flange. Next a rounded tool coaxes the metal undercut on the staff into a tight doughnut shape against the wheel, with slightly weightier taps as we rotate the wheel around. Followed by the flat tool again to flatten the created rivet. The wheel now undergoes a series of checks for equal weight balance, freedom of rotation (does it spin), and to finally check if it’s true. 'Does the wheel wobble and if so why', is the question we ask as we look closely to check if we have achieved parallelism or not. This is the stage at which Nick steps in for the final finessing and checking stages, and whilst I and another apprentice may know the process, we are yet to learn the art and finer details.  

After all is said and done, we can boil the process down to two key points; the correct selection of tools and the right amount of force applied. 

To add another layer to this instructional narrative, the balance staffs for the pocket watches in this learning process, were not sourced the same way we may for a watch you wear on your wrist. These pocket watches are over sixty years old and Seiko no longer supplies replacement parts for them. Luckily, back in 70's there was a third party balance staff manufacturer who made parts for this calibre, and thanks to their visionary efforts, we are now able to repair old Seiko railway pocket watches. Obviously, the third party maker hardly made any profit from investing time and efforts into making those parts, so from a business perspective that was a kind of failure. Yet if it wasn't for that 'failure', restoration of vintage Seiko pocket watches would be almost impossible.

Chloe, first year apprentice.

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