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Discussion Starter · #1 ·
Authored by Harry, Denmark

Having seen a number of questions regarding the fitting of new crystals to Seiko divers, I have prepared the following simple guide. From the outset I would like to say that anyone can do this, with a few simple tools, even if their 9-year old son William is watching and has an inexhaustible line of questions.

Start with a clean work area. A sheet of printer paper gives a nice, dust-free work surface. The crystal is a domed sapphire crystal from Harold Ng (Yobokies), the watch is a wonderfully patinaed original vintage Seiko 6309 on a Super Oyster with Yobokies solid end links:

Using a sharp pocketknife, ease the bezel off by pushing the knife under the crystal and twisting gently. The bezel will pop off. Take care not to lose the small steel ratcheting ball.

Tell William to keep quiet. Use a rubber-ball (or other) caseback remover to...remove the caseback:

Press down on the retaining mechanism and remove the crown:

Turn the watch over and gently tip out the movement. Cover the movement with a shot glass:

Get another shot glass, pour a whiskey and tell William to keep quiet. Rummage in your box of tools and find the crystal press:

Remove the crystal retaining ring in the same way you removed the bezel:

Send William out to blow his nose. Crystal retaining ring removed:

Use crystal press to remove crystal. A firm squeeze:

...and it pops right out. Check the condition and orientation of the crystal gasket and wipe it with a smear of silicone grease:

Clean the surrounding area with a Q-tip:

Press the new crystal in with the crystal press, checking that the crystal gasket is not pinched:

Place the crystal retaining ring in position:

...and use the crystal press to snap it home:

Insert the movement and crown, making sure the chapter ring lines up:

Lubricate the caseback with a dab of silicone grease and fit, after which the bezel can be snapped on using the crystal press:

And admire your handiwork, after unlocking the cupboard and letting William out:

Time taken: a little over 10 minutes.

THE VERDICT: it was a pleasure to deal with Yobokies, in the same way it is a pleasure to deal with our other suppliers of Seiko parts. We really need to stop from time to time and thank our blessings by having suppliers who also are enthusiasts.

The crystal is a wonderful upgrade to the flat Seiko original. The gentle dome gives depth to the dial and creates a wonderful play when moving the watch. The dome gives life to the watch and makes it look like it is under water, even when it is not. The AR coating on the inside of the watch gives fascinating blue reflections (see last picture) and makes the dial easy to read at all angles. The fact that it is a scratch resistant sapphire gives peace of mind in daily use. In all, a "mod" which improves an already perfect watch. SCORE: 10/10.

Discussion Starter · #2 ·
: "Hi, thought id give this a go just purchased some tools from EBay and already have the crystal and black chapter ring from Harold Ng , was wondering is it easy to change the chapter ring as well while doing this job and what kind of silicone grease do you recomend,thanks"
The crystal needs to be removed in order to remove the chapter ring, so this is the perfect time to do it. I use the silicone grease we have in small tubes in the lab, which we use to lubricate our pippettes - I have no idea how "heavy" it is. I hear people use a drop of the silicone "oil" available in auto parts stores to lubricate their gaskets. Apparently the oil risks "running" though and staining the chapter ring and dial so no more than a thin smear would be sufficient.

6,987 Posts
great thread..william would be proud
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