ZF factory RM035-02 disassemble and observations of construction. This only applies to the version 4. I can’t speak to any other versions or factory. I took the time to write this up, in case anyone else wants to try someday. I could find nothing online, so I had to wing it. As a side not, the 6T15 and 6T28 are in the same series, but due to modifications made to the 6T15, the 6T28 is not a drop in replacement. It could be done, and the results are nice, but should be done by a watchsmith. The benefit would be a full tear-down would also include a full clean and lub. So it might be worth it for some.
Originally my goal was to get a carbon fiber case to build my own custom watch with. I really like the design of the RM025, but was not looking to spend over $700 on one, and wanted more of a homage than a rep. But after finding out that my TD could not get just a case/crystal, crown assembly, I sprung for the latest version 4 with the hopes of replacing the 6T15 that it comes with, with a 6T28 to allow at least some mechanical movement to be seen. So, this is how is went:
The back side work- 1st was to remove the back. Most of the screws were not snugged up, so I knew I would want to snug them up a bit more after the transplant was complete to avoid them falling out. But I was happy to see a case back rubber seal installed. It is just a standard round O ring stretched around the steel bezel that holds the crystal. So the back seemed well sealed overall. 2nd was to remove the rotor, to make sure it would fit the new movement. After taking off the back, I discovered the small plate with 3 screws that is in the center of the rotor is all fake. The plate it just held on with a drop of rubber cement, and the 3 screws are just tiny fake screw heads that are also glued on. I image over time, if the watch is in a hot environment, they might fall off. Not sure, but after lifting the fake plate off, the one slotted nut that is found on Myota movements was revealed. Easy, it just unscrewed and the rotor was removed. I then removed the 5 point screws in the corners. I discovered they do not do anything, just for looks. I then removed the rear deco plate. With the rotor removed, 2 small (very small!) slotted screws hold it on. But, this is not just deco, it also holds a small winding gear. So once removed, the gear falls out. This gear provides the clutch function. Without it, the watch will not stay wound, so it has to go back upon reassembly. This is the first customization that the 6T15 has. So in order to use the 6T28, some component swapping would be required to use the deco plate on another movement. If push came to shove, I was prepared to just use the stock 6T28 rotor if needed and just paint it black. Then the stem/crown needs to be removed. It is a standard small indent that gets pushed to remove e stem. Standard process.
Now for the front- I removed the front cover assembly and was happy to see a thick custom rubber seal around the crystal housing. Very substantial. Next, the plastic chapter ring just lifts out. It needs to be lifted out straight or it will bind. It is a nice snug fit. For those that do not like the smaller little “sign” on the left with “RM035-02 RAFA” and the not-so-well spaced “Swiss Made”, this would be an easy swap. Next I removed the hands. Now the entire movement with deco comes out. There are two deco plates on the front of the movement. The top one is held on by the 4 corner screws. 2 are long and 2 are short. The longer ones hold the entire assembly together and the 2 shorter ones are more for looks. They all should have been long, as one of the short ones was stripped. They only hold on by 1-2 threads, so they must have over tightened it when assembled in the factory. Once these 4 corner screws are removed, the top deco plate can come off. The next deco plate is held on by 2 small slotted screws (VERY SMALL). One is hidden behind the large gear in the upper left corner (the one with 32 jewels next to it), the other one is revealed just under the hands, next to the posts, once the hands are removed. The interesting thing is, this screw is located in an area that is removed in the 6T28, so if the 6T28 were used, the screw could not be replaced. This is ok because the center plate that holds the movement is a snug wrap, and the top deco plate would hold it all other anyway, but that one screw under the gear would still be needed. I removed the larger gear, a smaller gear just under the hands (it drives the gears from the hour hand gear so the deco gears move when the time is adjusted). Now the 2nd deco plate lifts off. The movement is now fully removable for service or mods.
I did apply silicone lube to the seals before re-assembly, and also applied Swiss watch oil to the rotor bearings, but otherwise unchanged.
In summary, these are my observations:
1. The NTPT case is a work of art. The material is flawless, and the machining/milling is perfect. Very sharp and clean machine work, and no ragged or chipped edges, no bad surface finishes, just clean, high quality work. This can be seen just by removing the strap to see some of the hidden work. Very well done.
2. The case seems to be well sealed. I cant speak to the crystal gaskets, but the front and back covers seem to be well sealed, and the crown has an internal steel structure and a standard crown seal (o-ring).
3. On my unit, the counter bores (for the 5 point screws) on the front and back plate were undersize on diameter. My new 5 prong driver would not fit (it was exactly 2.7mm diameter). I had to polish the OD of the driver down so it would fit the counter bores to remove the screws. Same with the 4 point strap driver. I just took the driver tip out of the handle, chucked it in my cordless driver chuck and ground the OD down on an India stone until it fit into the counter bores. I tapered it too so the prongs would not get too thin and weak.
4. I ordered the small 5 prong movement driver to use on the movement swap, but it was not needed. The 5 prong case driver worked on all large screws inside, and a very small slot driver is all that is needed for the rest. There are several decorative screws that could be removed with the smaller driver, but they only need to be removed if someone wanted to modify the deco.
5. Replacing the back deco plate was a nightmare. That one gear must be aligned properly for the main spring tension to be retained. Plus those two small screws have to be replaced while the gear is positioned. Much patience, and a few choice words were needed, but I finally got it together.
6. The only left over piece was that small deco plate in the center of the rotor. I kept it, but did not put it back on. I was concerned it might fall off some day. But if I want to, I can easily put it back someday. But it looks fine without it anyway.
7. The ratcheting system used on the rotor is loud. Not as in defective, but just a loud system. Not a big deal to me.
8. The rotor assembly overall seems to also be modified to use the rear deco plate. So once again, some parts of the movement might need to be transplanted if the 6T28 were to be used.
9. Once disassembled, I did notice a very small crack and chip in the corner of the crystal. Not really visible once assembled (the dark chapter ring makes it hard to see). I assume they did this when pressing the crystal into the cover housing.
10. The strap is nice and seems to be high quality, but I do not like the very thin rubber that holds the buckle assembly. I feel it will break over time. So a velcor strap is coming. But I do plan to make adapters so I can use any 24mm strap I want. Should have some prototypes in a week or so.
11. Overall, the inside was clean and no debris was found. Now that I know the movement is modified, I am a bit concerned about how well it was done, but I wont lose any sleep over it. If it dies, I will just make it into a custom homage, with an all new deco and put the 6T28 into it for a proper skeletal watch, but with a really nice NTPT case (yes, I am a bit of a material whore).
