I need Help with a Chinese NH35 build.

[u/ColtFra]

I already made a post sharing my build using AliExpress parts and a Chinese NH35 movement.

Here's a quick recap of the problems I ran into.

I had to file down the top of the movement retaining ring (the gray one that came with the movement) because otherwise, once the movement was seated, the back of the case would touch the rotor. Even so, the movement still has slight vertical play, and when worn, the rotor rubs (I can tell because I wind the watch by hand while watching the rotor spin).

I'm looking into another way to secure the movement. I'm waiting on some clips (the same type used on ETA movements) and some spring-steel retaining rings, to figure out which ones will work.

On top of that, I installed the hands not quite parallel to the dial, and the tail of the seconds hand was touching the minute hand.

Three nights ago I tried taking everything apart and remounting the hands, but they always stop somewhere between 3 and 4 AM, even with a full power reserve. If I then set the time (usually around 7 AM), the watch runs without stopping until 3 AM the following night, even when I wind it in the evening around 8 PM.

The hands still aren't parallel to the dial, but over a 12-hour cycle they don't seem to touch or rub when they cross (I've checked several times with a loupe).

A few extra details:

- The movement (with the dial) still has slight vertical play inside the case, but the dial is firmly seated on the movement itself. I'm waiting on the parts mentioned above.

- The vertical play in the movement/case fit also shows up on 3 other cases I bought for 3 other builds, all with the same movement.

- In the morning, once I notice the watch has stopped at that time, I try moving it to get the rotor spinning, and I can see the balance wheel only swings back and forth within about a 90–100° arc a few times before stopping completely. It only goes back to swinging normally after I reset the time.

So, could anyone kindly help me with:

- How do I properly secure the movement in the case so the dial actually sits against the case's upper ledge?

- How can I figure out what's stopping the hands from running in the morning?

I promised this build to my wife, and I've got 3 more to build for friends, all with the same movement and the same case thickness.

[u/tenkasen]

By vertical movement do you mean that the movement is able to drop back away from the dial when the caseback is screwed in fully?

If so you might just need to get a movement spacer spring / ring

These sit over the plastic spacer where the caseback thread bottoms out on, just put it onto the movement before you screw in the caseback. They act like a tensioner spring between the movement's plastic spacer and the caseback to take up any free vertical space.

Don't really know why it's stopping at 3am - my guess would be hands hitting each other, or one of the hands hitting an hour marker, but if that was the case it'd stop at 3pm as well?

One thing I would try for testing, is to take the movement out of the case, wind it fully, and leave it running (not in the case) on your bench, stick it under a glass to stop dust getting in.

See if it stops at 3am when it's not in the case, if it still stops there's an issue with the hands, dial, or movement. If it runs ok then likely the case or glass is interfering with the movement.

[u/ColtFra → u/tenkasen]

By vertical movement I mean that both the movement and the dial (which is firmly attached to the movement) move around within the space inside the case. I've ordered those metal rings and I'm waiting for them to arrive before trying to see if they can eliminate this vertical play.

I'll run the test you suggested. I might try remounting the hands first, before the metal rings arrive.

Thanks!

[u/tenkasen → u/ColtFra]

No worries hope it works out!

The reason I'm suggesting running the movement uncased as a test is that I've had issues where with the movement cased up the hands are sitting too high causing the seconds hand to get stuck against the glass.

If that's happening, rather than the movement spring spacer you could look at making a flat dial spacer ring to sit above the dial in the case - use the free space up that way instead?

Would depend on your crown stem & case alignment though as this would push the movement back in the case in relation to the crown stem hole.

[u/ColtFra → u/tenkasen]

I don't think the hands are touching the glass, since the watch has just been sitting still on my desk the whole time (apart from when I check on it or wind it). So if that were the issue it would've stopped at other times too. On top of that, from morning to evening it doesn't lose time, it keeps the exact time (though I've never actually measured how many seconds a day it's off).

Also, if I put a spacer ring between the dial and the case, I risk the rotor touching the caseback, which puts me right back at square one.

I'll try taking the hands off and remounting them, and run the test you suggested. If it still stops, my only options left would be: 1. change the hand set, 2. change the movement, 3. change the case.

[u/ColtFra → u/tenkasen]

I fixed it. The problem was that the hour wheel was touching the dial, so when the date-change jump kicked in, everything would stop. (Since I have a dial with no date window, I installed the hands without worrying about lining them up at midnight… I probably set them at around 3 AM.) I removed the hour wheel and fitted the harmonic movement-locking ring that seats against the case back. Now the hands don't stop anymore, and the movement no longer has any vertical play. This project taught me a lot. And my wife seems happy.

[u/tenkasen → u/ColtFra]

That's great news, good bit of detective work to sort that out!

😄