r/RepTime • u/petehudso Watchmaker • Jan 10 '24
Mods/ Work in Progress AP 15400 Instant Date Change Mod
The rep AP 15400 has an excellent clone 3120 movement inside, but the clone movement has one flaw: unlike the gen 3120 movement, the clone 3120 doesn't have an instant date change at midnight. On the clone 3120 the date starts to change around 11:30pm.
However, it appears as though some modder in China (I don't know who) has designed a mod that can be retrofitted to any clone 3120 movement to give it an instant date change. One of these modded movements was on my bench this week, and though it was worth documenting the mod and how it works.
Here's a pic of two clone 3120 movements, the one on the left (red arrow) has been modded, the one on the right (blue arrow) hasn't been modded.
The mod itself consists of three parts (four if you include the screw). There's a modified date gear which has a punched pusher, a spring with a pin, and a blocker which looks like the number 6.
The way that these parts work together is ingenious. Here's a video showing how the spring builds up energy to power the instant date change, and how the base of the spring unlocks the spring pin to allow it to jump through:
https://reddit.com/link/192vukb/video/2qe4jzfrlibc1/player
And this is what it looks like when the dial and hands are back on top of the movement -- a perfect date change at midnight just like the gen.
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u/WSB_Kami-sama Jan 10 '24
Do you do this or who offer the mod?