I screw crown in, NH38 stops after an hour

[Nickpan]

rotor always moved even when tight

[AndyGSi]

11 minutes ago, Nickpan said:

rotor always moved even when tight

Is that still the same with the new one?

Is the rotor bridge secured correctly?

[Nickpan]

yes and yes

[ColinC]

Perhaps a stupid question.... but when you do the case up tightly are you pushing the seconds hand into the crystal?

[AndyGSi]

2 minutes ago, Nickpan said:

yes and yes

My first thought is although the listing shows this

they're not genuine movements and that's where the fault is.

1 minute ago, ColinC said:

Perhaps a stupid question.... but when you do the case up tightly are you pushing the seconds hand into the crystal?

I'd thought that but would have expected it to stop pretty much straight away.

[Nickpan]

17 minutes ago, AndyGSi said:

My first thought is although the listing shows this

they're not genuine movements and that's where the fault is.

I'd thought that but would have expected it to stop pretty much straight away.

yes, fair enough, it was Aliexpress, at best I may have been unlucky with the case

[AndyGSi]

4 minutes ago, Nickpan said:

yes, fair enough, it was Aliexpress, at best I may have been unlucky with the case

If the rotors aren't smooth and have too much play then I'd put it down to them.

[Nickpan]

9 minutes ago, AndyGSi said:

If the rotors aren't smooth and have too much play then I'd put it down to them.

hmm, that would suggest it had run out of power and wasn't re-winding itself (both movements), but I manually pre-powered it by turning the screw on the mainspring

Edited March 19 by Nickpan

[AndyGSi]

2 hours ago, Nickpan said:

hmm, that would suggest it had run out of power and wasn't re-winding itself (both movements), but I manually pre-powered it by turning the screw on the mainspring

Sorry I didn't mean it was down to the rotors and lack of power but down to the movements themselves in general.

[Nickpan]

I realise I have a brass dial, which tend to be thicker, so that will be my next thing to fiddle with.  

Watch has been running fine for 24 hours now, but with the back cover v-e-r-y  loose!  Not ideal, but it's nice to see it on my wrist ticking away.  Have a bad feeling it will stop again, them I'll measure the dial thickness.

[AndyGSi]

Dial should be 0.4mm thick.

[Nickpan]

15 hours ago, AndyGSi said:

Dial should be 0.4mm thick.

yes, it seems brass ones can be up to 0.8mm, which could be the difference between a loose caseback, and a tighty!

[AndyGSi]

1 hour ago, Nickpan said:

yes, it seems brass ones can be up to 0.8mm, which could be the difference between a loose caseback, and a tighty!

A 0.8mm Dial would only give 0.2mm clearance for the Hour Hand instead of the 0.6mm specified (unless you've got the L (HH) version).

[Nickpan]

and what is the height difference between a loose case and a tight one  - one doesn't have to look very far to find a watchmaker saying 'every thou makes a difference' 

Edited March 22 by Nickpan

[Nickpan]

I asked the same question on 'Seiko Mod' Facebook page, general opinion was 'your watch stops because the hands touch the glass'.

So, I trimmed the seconds hand by about 5mm, aligned it to be a lot close to the second hand, and gavethe central pinion bit an extra press, squash the seconds hand down.

Works a treat

On 3/19/2025 at 11:29 AM, ColinC said:

Perhaps a stupid question.... but when you do the case up tightly are you pushing the seconds hand into the crystal?

winner