Pressure Test Results for a Daytona with “screwed-up“ Pushers

[Prof. Rolex]

Dear Rolex-Fans,
sometimes the question comes up, whether a Daytona with pushers in the “screwed-up” position is still waterproof. The manual says clearly, that the Daytona is waterproof only with screwed-down pushers. But is the Daytona with screwed-up pushers really untight? For answering this question my Daytona 116520 was subject to two pressure tests, one with screwed-up and one with screwed-down pushers.

Tested watch: Rolex Daytona, Ref. 116520, bought 28th November 2004 at my AD Bucherer in Interlaken/Switzerland, Serial-No. F 708xxx:


Measuring instrument: Witschi ALC-2000

Testresult:

(Left side: pushers screwed-up, right side: pushers screwed-down)

The result is surprising: The test was okay in unscrewed and screwed position of the pushers!

The differences in the testresults between screwed-up and screwed-down pushers are very small and within the tolerance of the ALC-2000. With a testpressure of +1.0 bar the difference of deformation between both tests is only 0.3 1/1000 mm, with +3.0 bar only 0.5 1/1000 mm. Probably the deformability of the watchcase is slightly different with screwed-down pushers, because of a higher stiffness due to a bracingeffect with screwed-down pushers. The differences in the change of the deformation in a certain time (tightness value) are also within the tolerance of the measuring instrument. Therefore it can be concluded, that the Daytona is also tight with unscrewed pushers.

But please keep in mind, that the test unfortunately was made only with a max. pressure of 3 bar. This is sufficient for the normal use (washing of hands, showering, etc.), but unsufficient for a final statement about the tightness for swimming and/or diving with unscrewed pushers (necessary is a test pressure of min. 10 bar). In any case it must be avoided to operate an unscrewed pusher under water, because then most probably the water will come into the watch. May be that is the reason for the screwable pushers, because a pusher in “screwed-down” position is blocked and cannot be pushed.

For those who are interested in the physics behind the pressure tests:
Have a look to the homepage of Witschi (www.witschi.com) and download the phantastic interactive animation of the ALC-2000 (under downloads, presentation of devices, ALC-2000).

Best Regards
Matthias

[jholbrook]

Wow...thanks so much for posting this!

I've done similar testing....though a BIT less scientific...meaning, I've washed my hands while a pusher was unscrewed more than once.