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Rolex early Submariner ref. 6204 twin build project

matzemedia

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This is a build thread for two early Submariner ref. 6204 from @manodeoro and me. We started our project about a year ago and would like to share our process step by step. There are a lot of sources to get parts for the newer Submariner but it gets really difficult when it comes to the early one. Our goal was to build this early Submariner as close as possible.


Gen pic posted by Nanuq

But before I step down the rabbit hole, let me tell you a bit about the ref. 6204. Maybe some of you already know, but for the rest, it could be interesting.
 

matzemedia

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History Rolex Submariner 6204

The Rolex Submariner Reference 6204 was developed in 1953 and is considered the very first Submariner, laying the foundation for one of the most iconic dive watch lines in the world. It was officially introduced at the Basel Watch Fair in 1954. For its time, the watch was a technical innovation, offering water resistance up to 100 meters, and was aimed at both professional divers and sports-oriented customers.



During its early production phase, the Ref. 6204 exhibited subtle design restraint, particularly evident in the evolution of its dial variants. Some early models did not yet feature the "Submariner" text on the dial, likely due to branding considerations or the experimental nature of the initial series. Later, the text was introduced—typically in gilt print on a black dial, known as a "Gilt Dial," which is highly sought after today. The design details varied slightly depending on the production batch, which adds to the appeal and complexity for collectors.



A particularly rare and historically significant variation is the so-called "Sub-Aqua" dial. This version appeared on a very limited number of Ref. 6204 models, likely in association with the British Sub-Aqua Club, one of the earliest organized diving clubs in the UK. These watches featured the additional "Sub-Aqua" inscription on the dial and were not sold commercially, but rather used for demonstration or field-testing among professional or semi-professional divers. As a result, very few pieces were made—and surviving originals with this marking are now considered exceptionally rare and highly prized collector's items with deep roots in the early history of recreational diving.



Historically, the Ref. 6204 marks the transition from traditional wristwatches to robust tool watches. It was part of Rolex’s pioneering efforts in the field of professional dive watches and was soon followed in the same year by other references like the 6205 and 6200, each with its own unique characteristics. Nonetheless, the Ref. 6204 remains the starting point of the Submariner line and is today a rare and historically important watch—especially in elusive variants like the “Sub-Aqua”.
 

matzemedia

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How the twin build starts

I had the first contact to @manodeoro when he built a 6538 dial for my watch. He checked that I can do metal work at my lathe. Manodeoro should me his idea of a early "Sub-Aqua" and asked me to help him to create his case. After some PM we decided to build two Ref. 6204 with all the knowledge and techniques we have together. So a lot of information and images we will share are now from our PM during the build phase.



My previous build 6538 with the dial work of @manodeoro. Full build story
 

matzemedia

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The 6204 case

Well there is no affordable 6204 aftermarket case you can buy. But there are some 6538 cases you can find. 6204 and 6538 cases are really close but with some "huge" differences. On the pic below you can see that the 6204 case is much thinner than the 6538 one. 6204 is more or less 4.7mm thick at the crown while the 6538 is 5.3mm thick. So about 0.6mm difference.



Second "huge" difference is the rehaut opening: more or less 27.1 mm on a 6204 and 26.1 mm on a 6538. That is why the original 6538s took 12.50 mm hands and 6204 took 13.00 mm hands as you can see on the pic below.


Source: https://rolexhaven.com/
 
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matzemedia

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First prototype

I am not in the position to build a full midcase with my lathe skills. But I'am able to modify a given case. So we checked different cases like the Silix, Tiger Concept 5508 and did a first prototype out of a wrecked Silix. The goal was to create a 1:1 midcase which:

  • fits the gen 25-16 crystal
  • uses retaining ring crystal mount
  • has the crown at the middle
  • has the right height

So we followed the following idea by creating a custom rehaut and removing the rehaut from the original Silix case and gluing the custom rehaut into the Silix case.



And that is the result of the first midcase prototype (step by step)



 

369mafia

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Sweet project !! I am here for it.

The tube hole looks large and very close to the bottom edge... are you going to press in a plug and redrill?

excellent progress so far.
 
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kilowattore

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Great project, eager to see how it ends up!!
Glueing in a custom rehaut sounds a little risky but I guess based on your experience you evaluated the risk of it getting loose and eventually falling during use is minimal? Great stuff!
 
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matzemedia

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The tube hole looks large and very close to the bottom edge... are you going to press in a plug and redrill?
Well, you are right. This shows that the Silix case is not working as it should. I did a bit of a hack just to complete the PoC and drilled a new crown hole at the opposite site and closed the original with a glued-in screw.





Glueing in a custom rehaut sounds a little risky
That's what we thought at first. However, if you calculate the force that a 2K adhesive can hold, I was reassured: using a 2-part epoxy glue can handle up to 30N/mm². I calculated a 240mm² adhesive surface. So the clue should handle up to 7.2KN => 734kg. That sounds enough, but only time will tell whether we are right.

Learning from the Prototype

  • The Silix case is not working proper
  • A eta 2824 movement will fit with its stem height
  • We can build a case with a thickness of 4.7mm and a watch with a total height of about 13mm
  • The hack closing a crown hole is not nice
So we know we need a better case basis. And that was the time when aliexpress started to sell a new 6538 case.
 

trash3939

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I don't have the metalworking skills that you have, so I made the 6538 using an Ali Express case.
2McoiQ.jpeg
 

matzemedia

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The Ali Express case
As I have already addressed, and a lot of you, we also found the 6538 case. And it is a good base - not perfect - but good.

Here some dimensions:
  • hight (inkl. crystal): 15mm
  • hight incl. bezel (without caseback): 8.1mm
  • hight mid-case: 5.3 - 5.5mm
  • lenght: 48.0mm
  • midcase outer: 38.2mm
  • inner diameter: 29.4mm
  • rehaut opener: 28.0mm
  • Bezel outer diameter: 38.9mm
  • bezel inner diameter: 33.5mm
  • bezel - insert diameter: 37.4mm

The crown is not 100% in the middle - but good enough.
There is some extra meterial for the caseback, we have to remove.
I put a eta 2824 inkl. dial into the case and the steam high is correct.
The only issue is the bezel outer diameter of 38.9mm - that is too big.



So @manodeoro did some technical drawings how we have to make the custom rehaut to create a ref 6204 ouf of the Aliexpress case

Aliexpress case: with glued crystal and fix retaining ring.



New custom 6204 with custom rehaut (purple) that fit a 25-16 crystal. To fit the new custom rehaut we have to remove the old rehaut like shown below.


From the bottom we removed the material to get the watch slimmer and closer to the 6204 ref.





And of cause we need two:
 

matzemedia

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Crystal and retaining ring
The ref 6204 use a 25-16 crystal. It is differnt to the 25-19 for the ref. 6538 or 5513 and difficult to find . We found a dealer from Italy who sell this rarity.
Here some dimenstion:
- interior diam : 28.9 mm
- exterior diam : 30.3 mm
- height : 5.4 mm




To fix the crystal and mount the bezel, Rolex build a retaining ring that press the crystal to the case. The out side of the retaining ring is also used to fix a wire for the bezel. Here a picture of a aftermarket 6542 version which is similar.



And here our version:





 

trash3939

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The difficulty with this ariexpress case is the location of the lug holes.

They are located high on the outside and overlap the chamfer, making machining difficult.
I wish there was a solution.
 

369mafia

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The difficulty with this ariexpress case is the location of the lug holes.

They are located high on the outside and overlap the chamfer, making machining difficult.
I wish there was a solution.
There is , you can press in rod and redrill them , but that isnt exactly easy...however Easy is off the table with these builds.

fantastic work Gents.....admirable efforts
 

trash3939

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There is , you can press in rod and redrill them , but that isnt exactly easy...however Easy is off the table with these builds.

fantastic work Gents.....admirable efforts
Thank you for your instruction



It seems really difficult.

I guess I would need a jig to position the holes correctly, and I don't think I could do it (lol).
 
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