Horological Meandering

AndrewD
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Shock resistance testing

Hi All,

Tom’s early Incabloc advertisements prompted me to read about shock resistance testing of watches and I thought you might be interested in the information too. ISO 1413:1984 is the common standard employed, but is relatively easy to achieve with modern watch design.

The International Organization for Standardization (ISO) document “ISO 1413:1984 Horology, Shock-resistant watches” describes the method of testing and specifies the minimum requirements that a watch must achieve in order to be described as shock resistant. Some of the watches that pass this test have “Shock Resistant” engraved on the watch. I assume “Shock Proof” is some literary licence taken by the manufacturers and obviously overstates the truth.

The test is based on the simulation of the shock received by a watch falling from a height of 1 m on to a horizontal hardwood surface.

In practice this is achieved by applying two shocks, one on the 9 o'clock side, and one perpendicular to the front of the watch on the crystal. The shock is delivered by a hard plastic hammer weighing 3 Kg mounted on a pendulum delivering an impact velocity of 4.43 m/s. The watch must be able to maintain its accuracy to +/- 60 seconds/day as measured before the test.

Attached are some photos from a 2004 PuristS tour of the JLC Manufacture. The link is provided for some interesting discussion on the forces involved .

Regards

Andrew