In this tutorial, we will cover one of the most popular modification on SEIKO watches - Changing To Sapphire Crystal.
**Applicable on most SEIKO watches.
*The toughest part of this mod would be pressing down the sapphire crystal evenly.
SEIKO Watches without bezel can skip this step and go straight to step 1.
The need for bezel removal is dependent on the custom build of bezel and bezel insert dimensions, and watch model. Example, SKX007, there is no need to remove the OEM bezel and bezel insert for crystal swap of similar OEM dimension. However, particular sapphire crystal with tight clearance will require you to remove the bezel.
On another hand for SKX013, its OEM bezel insert sitting on top of the bezel has a smaller inner circumference than the diameter of its crystal. Thus, it is crucial to remove the bezel prior to removing the crystal.
As a rule of thumb, removal of bezel is the best approach given how it allows you a full view of crystal-gasket-case alignment and proper crystal installation.
Guide on the removal of bezel will be on another article coming soon.
Here, we used a tool similar to Bergeon 5700-Z Case Opener. Makes opening and closing any watch cases a breeze. Also reducing chance of slippage and scratching of watch cases. Once the two bits are tighten onto the notches of the watch case back, anti-clockwise to open the watch case back while clockwise screws down and tighten it.
Alternatively, an economy case opener wrench (Looks similar to Bergeon 2819-08 Jaxa) may also suffice. Although, a case holder may also be required to enhance grip and provide ease of case back opening.
Once the movement is exposed. Prior to removing the movement, the crown and stem must be pulled out first. With a toothpick, gently push down on the lever (see images below). Thereafter, the crow and stem can be pull out easily. The lever required to push down to remove the crown and stem is generally very similar across all SEIKO movements (i.e. 7S26, 7S36, NH35, NH36, etc).
If the movement is griped onto the case tightly, using a small flat-head screw or a toothpick to gently pivot it out of the case. Then gently tip the movement off from the case back onto a cushion.
TIPS: For SEIKO 7S and 4R1x family non-hacking movements, if you are not comfortable with it running while doing the modification, the best way to stop the movement is to let it sit till the mainspring runs out of power reserve.
Once the movement is removed, it is time to remove the crystal from the watch case. A crystal press can also act as a crystal remover. Here, we are using a crystal rack press similar to Bergeon 6173. Alternatively, an economy crystal press would also suffice. The only difference would be the effort force required to produce the same result.
Invert and place the watch case on the crystal press, such that inner of the watch case is facing up. Place a perfect fitting size die that sits onto the crystal of the inner watch case and gently press. The crystal should come off very easily.
IMPORTANT: Dies are generally reversible. They come in two forms, either concave meant for dome crystals or flat meant for flat crystals. When removing the crystal, always select a CONCAVE DIE for the base that has tapered edge that sit nicely ON THE WATCH CASE. This space between the die and watch case allows the crystal to fall off to. If you select a die at the base that sits on the crystal, you will not be able to remove the crystal.
NOTE: Use microfibre cloth if you afraid of scratching the crystal. Although when done properly and gently, even if the die is duraluminum, the hardlex crystal should not be scratched in anyway.
Here, the next important step would be to ensure the crystal gasket is intact on the front of the watch case. Crystal gasket can either be semi-translucent or black in colour. If it comes off, just simply replace it back onto the watch case.
Next, place a new sapphire crystal on top of the watch case as evenly as possible. Once the watch case with the uninstalled sapphire crystal is on the crystal press, gently half-press the crystal into the watch case, release and rotate 90 degrees. Repeat one full 360 degrees turn.
IMPORTANT: Ensure that the correct size and side of the die is always used for domed and flat sapphire. Make sure the sapphire crystal is not directly pressing the crystal gasket. Damage to this gasket will jeopardise the water resistance of the watch case.
Finally, repeat the above process with a full pressure press. This method ensures an even and balance installation of the sapphire crystal onto the watch case, and that it is fully secured within the watch case.
TIPS: Always double check with a loupe at 4 angles: 3H, 6H, 9H and 12H. If they are balance across all angles, well done! If not, the sapphire crystal has to be removed and reinstalled.
Here, we used a compressed air canister to remove any dirts and dusts on the dial, hands and inner watch case. Extremely effective given the high air pressure. A cleaning putty or ethanol solution can also be used to remove any accidental fingerprints on the dial, hands and inner watch case.
IMPORTANT: To prevent hairline scratches, ONLY microfibre cloth should be used at all times.
Now for the finale. To encase the finished mod back into the watch case, sit the movement dial up, align the watch case to the movement and push the watch case onto the movement.
Next, flip the watch case over and expose the back of the movement. Ensure that the movement is properly align and fully pressed down within the watch case. If not, realign and press down on the plastic bracket of the movement with a toothpick. Check the alignment of the crown position. If the movement is perfectly aligned, inserting the stem with the crown through the watch case into the movement would be effortless and fluid.
Lastly, closing the case back. Ensure the case back gasket is intact. Then continue to screw down the case back in a clockwise direction.
Listed here are some of tools that we are used. Depending on individual, some tools might be different or might not be necessary. While in terms of cost, they are generally affordable if you do not mind using "China Made" tools. Swiss Made tools can cost anything to thousands of dollars. Of course, when it comes to quality, it is a huge difference. Either way you go, they both get the job done.
It is also important to wear gloves or finger cots to avoid direct contact of our fingers on the watch parts and, especially, the movement.
Courtesy of Eric Y / Lume Shot
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WARNING: Modification and/or customisation of a watch will generally void its warranty.