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Message: <blockquote data-quote="MrCat" data-source="post: 28247333" data-attributes="member: 38575"><p><a href="https://mailchi.mp/c9c9245c9428/theres-no-way-13386776?e=c9ff62683f" target="_blank">Here`s an AWSOME article</a> about one of the most robust watches built by Seiko.  The <strong>Seiko Tuna</strong>....</p><p></p><p>** 7C46 high torque quartz movement - said to be fully repairable </p><p>** Single piece case, machined entirely from a solid titanium block. No case back </p><p>** Whilst Swiss dive watches had a helium escape value, Seiko decided to build the watch so tightly sealed that no helium could get inside the watch in the first place  <img src="/styles/default/xenforo/smilies/default/lol.gif"  class="smilie" loading="lazy" alt=":lol:" title="LOL    :lol:" data-shortname=":lol:" />  Typical Japanese <img src="/styles/default/xenforo/smilies/default/D.gif"  class="smilie" loading="lazy" alt=":D" title="Big grin    :D" data-shortname=":D" /></p><p></p><p></p><p><strong><u>Copied from the article (credits to the original author):</u></strong></p><p></p><table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td>In the 1960s, both Swiss and Japanese watchmakers 'worked out' that when watches were used professionally for helium saturation diving at great depths, they <u>blew their glasses off during decompression</u>. The problem was - Helium. Under high pressure, the inert Helium gas could enter the watch through regular gasket constructions, building up pressure inside the watch, equal to the pressure outside of the watch at that depth. Then, while decompressing the diver, the helium gas couldn't get out quickly enough, and thus the build-up pressure inside the watch caused the glass to blow off.<br /> <br /> In order to allow for quick helium release, the Swiss decided to construct a case with a helium valve.<br /> <br /> The Japanese opted for another solution: <u>to construct and build a divers watch so 'tight' that the helium couldn't enter the watch in the first place</u>. Seiko's solution was found in a special type and construction of the gasket, combined with titanium monocoque casing.<br /> <br /> The first Tuna was built in 1975, fitted with an automatic movement, waterproof to 600m.<br /> <br /> The rest is the history.<br /> <br /> Three years later, another release: the new quartz Tuna. It was the world's first professional Diver's 600M featuring a world-class corrosion-proof, shock resistant, airtight case.<br /> <br /> In 1985 Seiko released a 1000m titanium Tuna with ceramic bezel protection fitted with a high grade quartz mechanism.<br /> This was not an ordinary battery operated watch, but one fitted with a purpose built mechanism: shock resistant, high torque, and super accurate. The diver's watch standard - robust, reliable, repairable - was set by Seiko.<br /> <br /> During the past couple of decades the market for divers watches exploded. New models offered everything from a dive computer to email and web browsing to banking. Yet only a handful of watches were still built to 1980s standard: a true 1000m water resistance.<br /> <br /> In 2020, the new-old Tuna was welcomed by tens of thousands of serious watch aficionados looking for 'an old fashioned, properly built, no-nonsense' divers watch. A classic watch featuring high-tech materials like titanium, coated steel, and ceramic. A repairable watch which could be passed on to the next generation. </td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td><p style="text-align: center"><img src="https://mcusercontent.com/27872ef1eb15e92361d40e896/images/a3595b94-7645-954e-020d-a40cc518b43a.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p> </td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td><strong>Inside the Tuna can</strong></td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td>The original plan was to publish here a couple of images to show the 7C46 movement as well as the single-piece titanium case. However, since no suitable images could be found, I has no choice but to dig into it myself.<br /> <br /> The disassembly starts with removing the 4 side screws with a 1.5mm hex key. Once the screws are removed, the ceramic 'shroud' comes off, as well as the rotating bezel.<br /> <br /> Underneath the bezel are two click springs which hold the bezel in position.</td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td><p style="text-align: center"><img src="https://mcusercontent.com/27872ef1eb15e92361d40e896/images/156da120-fbee-cf4a-87f6-f326d38f7142.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p> </td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td><p style="text-align: center"><img src="https://mcusercontent.com/27872ef1eb15e92361d40e896/images/3ae33bb4-652f-ce88-01fe-c42b12a8208b.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p> </td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td><p style="text-align: center"><img src="https://mcusercontent.com/27872ef1eb15e92361d40e896/images/bc4ce424-b7b2-f927-4655-a30bbdb23769.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p> </td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td>At this point in time, the watch is still fully waterproof, so removing the bezel protector for cleaning or for the replacement of the click/bezel itself does not affect water resistance. (Hint: you can clean the bezel yourself!)</td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td><p style="text-align: center"><img src="https://mcusercontent.com/27872ef1eb15e92361d40e896/images/f74e4bd5-d6b6-ba98-cc04-d53b87a28b32.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p> </td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td>Crystal removal requires a special tool. The crystal is held down by a screw-down bezel. Between the bezel and crystal there is a poly washer.</td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td><p style="text-align: center"><img src="https://mcusercontent.com/27872ef1eb15e92361d40e896/images/b0a0e3df-5afe-d59c-a4cc-f8ee334d98a8.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p> </td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td>The crystal's rubber seal is of a special shape, designed to 'hug' the crystal when pressurised.<br /> The crystal itself is a sapphire, flat, faceted, 4mm thick.</td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td><p style="text-align: center"><img src="https://mcusercontent.com/27872ef1eb15e92361d40e896/images/b40ba8fa-4949-573e-a2af-c0080fe11a2e.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p> </td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td>The next step is to remove the minute chapter ring. Underneath the chapter ring is a rubber O-ring which provides shock-absorbance for the dial and movement.</td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td><p style="text-align: center"><img src="https://mcusercontent.com/27872ef1eb15e92361d40e896/images/56140486-06b3-53ba-840d-b6b5c86fe811.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p> </td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td>Stem removed, movement extracted form the case.</td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td><p style="text-align: center"><img src="https://mcusercontent.com/27872ef1eb15e92361d40e896/images/e50f63bb-592d-7033-9229-1c722f689268.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p> </td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td><p style="text-align: left"><table style='width: 100%'><tr><td><p style="text-align: center"><img src="https://mcusercontent.com/27872ef1eb15e92361d40e896/images/adb1a9d1-c57e-b775-895f-552968afb9f0.jpg" alt="" class="fr-fic fr-dii fr-draggable " style="" /></p> </td></tr></table></p> </td></tr></table> <table style='width: 100%'><tr><td></td></tr></table></blockquote><p></p>

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