Workshop -4-
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A great part of repaired wristwatches are water proof or water resistant, with screwed back, demanding for particular care at the moment of case opening and especially of case closing. This Bergeon machine allows dealing easily with this problem: the hardest closed case can be easily opened with no risk of damaging. Furthermore, at the moment of closing it, it's possible to accurately measure force so the integrity of new gasket can be preserved. It must be remembered that a water resistant watch can be used sometimes in a situation where the life of its owner depends on it, typically during scuba diving. |
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Sometimes the teeth of a pocket watch wheel are slightly
worn. It's possible to repair it by hammering the teeth to expand their
profile and by reshaping them by cutters mounted on a machine like this. Its action is similar to the wheel-cutting machine seen on the previous page. The main difference is this machine can't create completely new wheels (nor pinions) because it hasn't got the ability of "indexing" the wheel dividing it in as many equal parts as the number of teeth is. Teeth must be at least approximately shaped. |
Here is how the tooth shape problem is treated on the "Encyclopedia"
| A selection of measuring instruments: two 1/100 mm. micrometers and a common gauge caliper used by every toolmaker. While the latter type can usually show the 1/20 mm. (2/1,000"), the former can show the 1/100 mm. (4/10,000"). If accurately made like the JKA with dial indicator and used by a skilled operator they arrive to show the 1/400 mm. (1/10,000"). These performances are useful for example in balance staff making when spare parts are no more available. |  |
A typical micrometer
This is a very old tool that we still use sometimes on lathe work. An old caliper like this is capable of measuring 1/100 mm. (4/10,000") on its brass graduated scale and most of all it is a very quick mean of taking a measurement (even if not with absolute reliability), because of its ingenious construction.
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About balance wheels, it's very important that they're properly "poised", in other words, every arc of their circumference must be of the same weight than any other. There is abundant literature on this matter. You can see the tool used for this job, which is called "poising tool". |
This microscope is used to observe small parts like pivots or balance staffs for wristwatches. Its magnifying power is limited to 20X or 40X, but it offers a "stereo" view, which allows depth of image to be appreciated, so it is possible to work on parts while looking at them. The focal distance is very high, so there's enough room between lenses and the observed part to allow the insertion of tools.
