WatchTech

ei8htohms
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Four escapements linked with differentials and each balance has a curb pin regulator?

Hello All,

This is a fascinating new piece from Roger Dubuis.



The Roger Dubuis Excalibur Quatuor boasts four independent escapements, each aligned 45° from "flat" (and 90° from each other) and linked with differentials to average out the errors. Do read about it if you haven't yet.

rogerdubuis.watchprosite.com

The thing is, most watch manufacturers serious about accuracy have removed curb pin regulators from their watches to insure rate stability over time in the real world, so why did Roger Dubuis use four of them in this beast?

Curb pin regulators introduce a timing error of their own into the isochronism equation. The idea is that they create an artifical and movable terminus for the hairspring that allows the watchmaker to adjust the rate by moving the regulator and effectively shortening or lengthening the length of the hairspring.

The fact that the curb pins have to have a small gap to allow them to move freely means that the time that the hairspring will be in contact with the pins will vary with amplitude (low amplitude will result in more time in the "free" space between the pins) . Clever engineers have factored this into the general design of the oscillator to capitalize on this error, but this is a work around when you consider that a properly designed hairspring (with an overcoil or variable geometry terminal curve especially) will perform better without curb pins.

Moreover, the sensitive adjustments employed to get the most favorable balancing of errors from a curb-pin-equipped oscillator are a critical source of weakness for watches in the real world. After a watchmaker spends significant time perfectly setting the distance between the curb pins and perfectly centering the hairspring between them (or leaning it on one side more heavily to correct for another error), a decent shock can throw the adjustments off and give you a significant rate error.

So is Roger Dubuis convinced that this watch will never actually be worn (plausible)? Or are they just not really that interested in actually delivering accuracy, and more interested in capitalizing on the perception of pursuing accuracy?

_john