review33.com:談天說地:坐井觀錶

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[#1] 坐井觀錶零X年某天突然對手錶產生濃厚興趣，除修讀了幾個遙距修錶課程外，也買了好多修錶書、工具、機芯來實習，雖然不算是一個正統修錶師傅，也算是一個手錶愛好者，平時逛街經過一些細錶舖、錶檔，會八八卦同啲修錶師傅閒聊，交流一下整錶心得，退休前長時間任職工程設計、生產及質量管理，習慣咗用另類角度睇人和事，有在外國相關錶網參與論錶，這裏嘗試提供一個另類平台，歡迎各師兄、師姐參與講錶及相關事宜，祗講錶不講人。		0925 正式會員 58.xxx.xxx.247	2016-10-02 12:14

[#2] 坐井觀錶
http://forums.watchuseek.com/f281/settling-great-crystal-debate-sapphire-vs-hardlex-140805.html

Sapphire crystal:
Artificial sapphire (as is used for watch crystals) is grown in a crystal lattice, unlike the flame-formed sapphire, like the kind you find in common graduation rings. The Sapphire crystals used in the overwhelming majority of watch crystals are artificially grown (in a boule. Once formed, the boule is then sliced and the pieces are then cut and polished to the desired shape. This material is very hard an very resistant to surface scratches from common every day use. However, it is also (like diamonds) brittle and even though it is 4 times harder than Hardlex, it has a tendency to cleave or shatter on impact (provided the impact is just right). Sapphire crystals are also far more difficult to manufacture to high tolerances (read, to avoid micro fissures which could lead to weakspots on the crystal) which adds to their high price. Be warned, not just because a watch has a sapphire crystal does it mean it has a high quality piece suitable for difficult environments such as scuba diving. Flame formed sapphire while chemically identical, lacks the internal crystalline structure and is much softer and brittle. Don't forget that despite myths to the contrary all crystals can be scratched - sapphire crystals are just more resistant to surface scratches.

Hardlex crystal:
Hardlex is a Seiko proprietary type of hardened mineral crystal and comes in at least two different varieties (what goes in Seiko 5's is not the same quality of what goes into ISO divers). Hardlex is closer to 7 in the Moh's scale, but is much more flexible than sapphire. IOW's sapphire is harder but more brittle. Hardlex will scratch easier but resists impact much better. You can read more about Hardlex and the different types of it here:

http://www.larrybiggs.net/scwf/index.php?mod=103&action=0&id=1037842045＞

Sapphlex is also a Seiko proprietary type of hardened mineral crystal that is laminated (layered on the outer side of the crystal) with sapphire. The idea being to provide the best of both sapphires's superior scratch resistance and Hardlex's superior impact resistance.

The types of plastics used to make acrylic crystals has varied widely throughout the years. From a performance POV there are acrylics out there which perform very well in professional divers (most dive computers today use acrylic crystals). The problems with acrylics are that although they can be made to be very very impact and preasure resistant (at least in higher end ones), they are highly susceptible to scratches from simple bumps that would normally not scratch a simple mineral crystal. Provided the scratches are not too deep, they can generally be easily buffed out with the appropriate tools.

Buffing out scratches on mineral crystals (of any kind - sapphire included) is possible, but difficult and time consuming. even then if you are able to remove the scratch, you run the risk of altering the shape of the crystal in that spot. There are no real guaranties as to the quality of results. Although it is possible, it is usually not worth the time and effort to repolish a mineral crystal. Also, since replacements are generally inexpensive, most people prefer to just replace them.

0925

正式會員
58.xxx.xxx.247

2016-10-02 12:19

[#3] 坐井觀錶
一個質量好的機芯，經過調較后，與日常配帶習慣和卸帶后擺放位置相配合，可以做到好準確，我有隻 Ocean7 LM-7，5月8日較準后帶到而家，祗快了34秒。

最後修改時間: 2016-10-02 12:34:21

0925

正式會員
58.xxx.xxx.247

2016-10-02 12:33

[#4] 坐井觀錶
https://en.wikipedia.org/wiki/COSC

COSC standards

0925

正式會員
58.xxx.xxx.247

2016-10-02 12:37

[#5] 坐井觀錶
ISO 6425 divers' watches standard

The standards and features for diving watches are regulated by the ISO 6425 - Divers' watches international standard. ISO 6425 defines such watches as: A watch designed to withstand diving in water at depths of at least 100 m and processing a system to control the time. Diving watches are tested in static or still water under 125% of the rated (water)pressure, thus a watch with a 200 meter rating will be water resistant if it is stationary and under 250 meters of static water. The testing of the water resistance is fundamentally different from non-dive watches, because every watch has to be fully tested.

Besides water resistance standards to a minimum of 100 meter (330 ft) depth rating ISO 6425 also provides minimum requirements for mechanical diver's watches (quartz and digital watches have slightly differing readability requirements) such as:
• The presence of a time-preselecting device, for example a unidirectional rotating bezel or a digital display. Such a device shall be protected against inadvertent rotation or wrong manipulation. If it is a rotating bezel, it shall have a minute scale going up to 60 min. The markings indicating every 5 min shall be clearly indicated. The markings on the dial, if existing, shall be coordinated with those of the preselecting device and shall be clearly visible. If the preselecting device is a digital display, it shall be clearly visible.
• The following items of the watch shall be legible at a distance of 25 cm (9.84 in) in the dark:
o time (the minute hand shall be clearly distinguishable from the hour hand);
o set time of the time-preselecting device;
o indication that the watch is running (This is usually indicated by a running second hand with a luminous tip or tail.);
o in the case of battery-powered watches, a battery end-of-life indication
• The presence of an indication that the watch is running in total darkness. This is usually indicated by a running second hand with a luminous tip or tail.
• Magnetic resistance. This is tested by 3 expositions to a direct current magnetic field of 4,800 A/m. The watch must keep its accuracy to +/- 30 seconds/day as measured before the test despite the magnetic field.
• Shock resistance. This is tested by two shocks (one on the 9 o'clock side, and one to the crystal and perpendicular to the face). The shock is usually delivered by a hard plastic hammer mounted as a pendulum, so as to deliver a measured amount of energy, specifically, a 3 kg hammer with an impact velocity of 4.43 m/s. The change in rate allowed is +/- 60 seconds/day.
• Resistance to salty water. The watches under test shall be put in a 30 g/l NaCl (sodium chloride) solution and kept there for 24 hours at 18°C to 25°C. This test
www.avionica-watches.com
• water solution has salinity comparable to normal seawater. After this test, the case and accessories shall be examined for any possible changes. Moving parts, particularly the rotating bezel, shall be checked for correct functioning.
• Resistance of attachments to an external force (strap/band solidity). This is tested by applying a force of 200 N to each springbar (or attaching point) in opposite directions with no damage to the watch of attachment point. The bracelet of the watch being tested shall be closed.
• Marking. Watches conforming to ISO 6425 are marked with the word DIVER’S WATCH L M or DIVER'S L M to distinguish diving watches from look a like watches that are not suitable for actual scuba diving. The letter L indicates the diving depth, in metres, guaranteed by the manufacturer.

0925

正式會員
58.xxx.xxx.247

2016-10-02 12:56

[#6] 坐井觀錶
0925兄下一步應該係自己造錶 :) 再創立品牌

newnew

正式會員
202.xxx.xxx.229

2016-10-02 12:57

[#7] 坐井觀錶
newnew兄，有想過，亦 draft 咗幾張錶殼 drawings，想話做一個 series 的基準底座配帶，上面套不同款錶頭，不過問過啲廠，MOQ 數量唔細，國內細廠質量/精度未達要求，番鬼佬報價又太貴，自己又咁上下年紀，作罷了。

0925

正式會員
58.xxx.xxx.247

2016-10-02 13:09

[#8] 坐井觀錶
Swatch常用機芯，拾幾年前買3隻練洗油，其中一隻裝了殼。