τυποι κορωνας

[GiannisH]

   Φίλε Παναγιώτη και όλοι οι επί του θέματος συνομιλητές, όσο με αφορά το μπράβο σε κάθε νέα προσπάθεια από τον οποινδήποτε ισχύει και θα ισχύει για όλους τους τομείς της ζωής. Ίσως η κουβέντα έπρεπε να είχε ξεκινήσει από την παράθεση των σχεδίων και μετά. Έτσι ούτε βιαστικά μπράβο ούτε βιαστικές καταδίκες θα υπήρχαν

   Από κει και μετά, θα ήταν ενδιαφέρον νομίζω να δούμε(με καλή διάθεση) τι εγγυήσεις δίνει η εταιρεία, τι ζητά σαν σέρβις και ενδεχομένως αν έχει κάποιες ιδιαιτερότητες στην εφαρμογή της υλοποίησης(ως αναφορά τα υλικά που έχουν χρησιμοποιηθεί, την κατεργασία κλπ)

   Έχω την εντύπωση χωρίς να είμαι σίγουρος, ότι πέραν και της Tag Heuer, έχω δεί κι άλλη εταιρεία να διαφημίζει χρονογράφο που λειτουργεί στο νερό. Δεν έχω καταφέρει ακόμη να θυμηθώ ποιά, ελπίζω να μου έρθει κάποια στιγμή  

[george_]

έχω δεί κι άλλη εταιρεία να διαφημίζει χρονογράφο που λειτουργεί στο νερό.


να λειτουργει σε υψηλες πιεσεις.η λυση ειναι "συμβατικη",μαλλον εχουμε καποιους συμβιβασμους..και οι μεγαλοι δεν το καταφεραν?οχι απλα ,επειδη εχουν φημη,ιστορια και πολλα $$$$$$$ ,δεν εχουν αναγκη να κανουν τετοιου στυλ διαφημισεις..με τεχνικες λυσεις που αφηνουν ερωτηματικα

[blackbird]

Η Ταγκ στο κατειργημένο Άκουαγκράφ, πού 'σαι Γιωρίκα, υιοθετούσε άλλη λύση. Είχε καλυμένα τα κουμπιά με καουτσούκ. Στεγανότητα στα 500μ.

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Δημήτρης

[konakis]

ωραίο βιντεάκι b&b ................ θυμίζει κατι αντίστοιχα της IWC και σε ήχο-εικόνα και σε παραστατικότητα (βυθό-λειτουργικότητα)

[kostas]

Η Ταγκ στο κατειργημένο Άκουαγκράφ, πού 'σαι Γιωρίκα, υιοθετούσε άλλη λύση. Είχε καλυμένα τα κουμπιά με καουτσούκ. Στεγανότητα στα 500μ.


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σωστός.

είναι μία μέση λύση, νομίζω όμως πως σαφώς είναι η πλέον προσιτή για τους ερασιτέχνες.

[blackbird]

Η μόνη ένστασή μου είναι μέχρι πότε θα υποστηρίζει η Ταγκ το ρολόι.

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[kostas]

Αυτό ακριβώς είχα κατά νου και εγώ.
Ναι μεν οι άλλοι χρησιμοποιούν πιό σύνθετες λύσεις, πλιν όμως όλα αυτά τα ο-ρινγκ κλπ πρέπει να είναι και τυποποιημένα, αλλά και εύκολα να κατασκευάζονται στο μέλλον.
Οι μεμβράνες αυτές επάνω από τα κουμπιά σαφώς και είναι "ειδικά" τεμάχια.

αν είχα τέτοιο ρολόι ίσως να αγόραζα κανά δύο ζεύγη ανταλλακτικά για κάβα, ποτέ δεν ξέρεις...

[george_]

Ενα αναλογο θεμα,εχουν ανοιξει στο wus...


I am getting a Fortis B42 Cosmonaunt watch next week, rated at 200 meters with Fortis non screw down crown (standard now on all B42 series watches)

Was wondering since these use double gaskets (internal) to retain the 200meter water resistance, and most dive watches use a screw down crown (traditional design from the original Rolex Subs I believe)

I have a few PADI/NAUI certifications but normally don't use a watch for diving anymore. Gave that up about 20 years ago after dive computers came out.


Rolex trip-lok stem/crown is now well copied by others.

Seems early dive watches from the 50's-60's had non screw down crowns.

Just curious

Most likely is based on watch manufacture techonology and giving divers who use watches a more secure feeling of water resistance with a screwed down crown. 


Earlier runs of the Fortis Marinemaster with the screw down crown had problems with the crown assembly, so they went with the non screw down design. Its 200m, so it should be fine.



Rolex trip-lok stem/crown is now well copied by others.


Actually, Rolex's "Triplock", with three sealing gaskets, is not used by any other watch manufacturers.* Most internally threaded screw down crowns are variations on the "Twinlock

[george_]

απο το ιδιο θεμα

iginally Posted by Jeff Caldwell  View Post
Panerai does not use a screw down crown, rather a crown locking device. I must admit for some reason I feel a screw down crown is more secure than a non screw down crown. When my PAM 024 first arrived I was devistated the crown did not screw in ( I just assumed it did and the locking device was just an added safety measure). I don't know that I am over this yet with the 24 but I am working on it . B/F anyone blast me, I know that it is the crown gaskets that ensure water resistance, not the "screw in crown" but I still just prefer a screw down crown on a diver (or any other watch for that matter).
The reason non-screw down crowns are less regarded for water resistance is 1) during winding and setting, the gasket rubs on the case tube and wears, 2) the amount of compression on the gasket decreases over time as the rubber wears and ages (rubber looses elasticity as it ages).

The improved water resistance of a screw down crown is the fact that there is improved compression of the gasket and no wear on at least one of the sealing gaskets. Further, as the rubber ages and looses elasticity, the crown can be screwed down a bit further as still maintain good compression.

The cammed crown on the Pamerai seals in a manner similar to a screw down crown without the trouble of threads. When the crown is cammed down, the rubber gasket is compressed vertically, which causes it to expand horizontally, this expansion causes the gasket to press against the stem and case tube and seal. When the stem is unlocked, and the gasket relaxed, there is reduced pressure on the gasket, so winding and setting does not cause as much wear on the gasket.
__________________
We ask for much in a watch, but 'tis noble movements that signify greatness. Let the measure of time be mechanical, not electronic [quartz].
- Ralph Waldo Emerstein (Watchmaker)


Enlightening as usual... but I have two questions:
The screw down crown can be tightened a little bit further and still maintain compression. But isn't the panerai crown assembly a "fixed" compression? It goes that far and not any further? In that sense a screw down seems to have an advantage because it can be tightened, unlike the Panerai crown guard.

Second question is, although a non screw down crown doesn't have the extra compression given by screwing it tighter, by pushing it, there's also some compression, just like in the Panerai assembly. So aside from the crown guard that keeps the Panerai crown in the lower position, Is there any real advantage to the Panerai crown assembly? (regarding the subject at hand and the explanation you provided about rubber elasticity and compression, of course...)



The Panerai design does not get "extra" compression like a screw down crown, but then it is not subjected to much wear so it does not need it.


I don't you understand how a non-screw down crown seals.

In the first image we see a non-screw down crown, the gasket "grips" the case tube to achieve compression, the amount of grip the gasket has, is related to the difference in inside diameter (ID) of the o-ring, the outside diameter (OD) of the case tube and the amount of elasticity of the o-ring. As the o-ring wears the ID of the o-ring increases and as it ages the elasticity drops, so you see the "grip" relaxes and the overpressure the seal can withstand drops.

Pushing the crown downwards does not affect the sealing in this case.




In this image we see a conceptualized diagram of a Panerai crown. In this case, the o-ring is designed to have little "grip" in the relaxed state. But, when the crown is pushed downward, the o-ring is squished flat, and the breadth increases. This effectively, decreases the ID and increases the OD of the o-ring, forming a tight seal against the wall of the tube and post portion of the crown.



There is usually little sealing on the upper and lower portion of the o-ring as one side is usually in contact with a washer. The washer is to protect the o-ring from rotational wear from either the crown or the case tube, whichever one the o-ring does not ride with.

For comparison, here is a screw down crown screwed down. you can see that the flat upper gasket takes the lion's share of the sealing duties, and will be subjected to no wear during winding and setting, while the back-up annual o-ring gasket will be subjected to the same wear as the non-screw down crown.




http://forums.watchuseek.com/showthread.php?t=414622