Modern Tongji Movement – Setting Time Engages All Gears

[Inumo]

So, I'm working on a modern tongji (aka Chinese standard) movement, which is to say: a cheap piece that isn't worth the labor of a professional. The challenge I'm running into is that, for some reason, when I pull the stem out to set the time it seems that the entire gear train gets engaged, so I can't actually set the time because I'm limited to moving at whatever rate/direction the escapement lets me. My best guess as to the problem is that the cannon pinion is normally able to rotate around the minute wheel and that's just failing somehow in my movement, but I also can't for the life of me imagine how you'd be able to let the cannon pinion freely rotate while also having it follow the minute wheel. If anyone has experience with this movement and can offer advice, I'd appreciate it; I'd rather not have to tear apart a functioning watch in the hopes of learning more when I can't trust I'll be able to put it back together safely.

[watchweasol]

I think you answered your own question, the dial and hands will have to come off to expose the setting mechanism.  Some canon pinions are free to rotate others are friction fitted depending on the watch.  Little alternative other than to have a look.

[jdm]

2 hours ago, Inumo said:

to set the time it seems that the entire gear train gets engaged

Seems just a stuck cannon pinion, not much disassembly is needed to fix that, however since these simple mov.ts are normally well built you may take the occasion for practicing a full service, check

 

[Inumo]

Thanks for the responses!

2 hours ago, watchweasol said:

I think you answered your own question, the dial and hands will have to come off to expose the setting mechanism.  Some canon pinions are free to rotate others are friction fitted depending on the watch.  Little alternative other than to have a look.

Sorry, new to the hobby here, so I suspect I'm failing to connect some obvious dots. I've disassembled & reassembled the setting mechanism a few times now (that was how I got to "the cannon pinion is the problem"), but is there a way to differentiate between free-rotating and friction fit pinions without disassembling another (functioning, at least in this capacity) watch? I know with another tongji movement watch that I'm planning to overhaul, I can apply some power through the gear train if I try to set the time going forward, but everything moves freely without applying power if I go backwards; is this indicative of anything? In either case, what's the next step? I'm not sure if this is a classic case of "if it's supposed to move and it isn't, apply lube" or if any oils I apply will cause problems by completely "disconnecting" movement in the minute wheel from movement on the front of the watch.

2 hours ago, jdm said:

Seems just a stuck cannon pinion, not much disassembly is needed to fix that, however since these simple mov.ts are normally well built you may take the occasion for practicing a full service, check

 

I actually came across this thread while I was trying to figure out what might be going on with my movements! Useful information, though by that point I'd already largely figured out how to take everything apart/put it back together. I think I'll hold off on giving this particular movement a full service for now, considering it's theoretically factory-fresh & thus shouldn't need to be given an overhaul just yet. I've got another watch that desperately needs an overhaul, though, so I'm sure I'll be referencing your thread soon enough.

[watchweasol]

Hi A friction fit cannon employs a notch/dent in the side of the pinion so when fitted it clicks and huggs the center shaft.  when its not tight the min hand soes not move.

Also when posting queries if possibe supply pictures of the movement in question It helps a lot.

[Inumo]

8 hours ago, watchweasol said:

Hi A friction fit cannon employs a notch/dent in the side of the pinion so when fitted it clicks and huggs the center shaft.  when its not tight the min hand soes not move.

Also when posting queries if possibe supply pictures of the movement in question It helps a lot.

Hm, okay. Based on this description, I'd guess this cannon pinion is free-rotating instead of a friction-fit (see pics for the pinion in situ sans hour wheel and the pinion on its own). Might be missing something, especially since it does take some force to remove the cannon pinion, but I honestly can't think of how this whole system would be able to function if the minute wheel & the cannon pinion were locked in sync. So, if it's not spinning when it should be, and given what I can see in some other watch movements' technical docs... I'm guessing apply some watch grease like Moebius 9501 to the stem of the minute wheel? Does that sound right?

Edited March 15, 2022 by Inumo

[jdm]

9 hours ago, Inumo said:

I'd guess this cannon pinion is free-rotating

There is no such thing. A watch with a lose cannon pinion runs inconsistently slow. And if there is no friction at all, the train runs including the second hand, but the hands don't move. And when  setting it one can tell right away that something is very wrong, because the hands spin all over the place.

[watchweasol]

Looking at your last picture of the canon pinion there is a dent in the tube this is for it to friction fit on to the center shaft from whence it gets its drive. Too little friction means no hand drive or loose hands too much friction makes the hand setting very stiff. so when adjusting the canon pinon you have to reach the happy mediun between hand setting and hand drive. What I meant regarding the free running is the t the center post is rivited to the plate and the canon slips over the post being driven by another wheel/pinion, not free to rotate loosely as that would be totaly useless.and impractical.

[Inumo]

Okay, good to know that my initial instinct where I said

On 3/15/2022 at 3:02 AM, Inumo said:

I also can't for the life of me imagine how you'd be able to let the cannon pinion freely rotate while also having it follow the minute wheel

was accurate, and I guess I just wasted some time with a misunderstanding of what "free to rotate" means between me and watchweasol, along with what a "notch/dent" looks like. At least through this I've come to understand that there's a balance of friction at play here, that it's not a true binary between "spins freely" and "turns only with the minute wheel." Unfortunately, this seems to put me back to square one; we got off-track trying to diagnose what kind of cannon pinion this is, but I still don't know how I'm supposed to fix a stuck cannon pinion. Again, new to the hobby here; I have basically-zero knowledge about what's par for the course for servicing watch movements. Is there some obvious fix that I'm just not recognizing? Google has a lot of advice about what to do when the cannon pinion can't be removed, but I'm seeing nothing for "the cannon pinion won't turn to let you set the time without engaging the entire gear train," so I'm guessing this is either an extremely rookie problem or an extremely niche one.

[HectorLooi]

I find your problem really strange. If the pallet fork has been re-installed, it should "lock up" the gear train and stop it from turning, even if the cannon pinion is very tight. So check your escape wheel and pallet fork for damage.

[jdm]

41 minutes ago, HectorLooi said:

I find your problem really strange.

Not strange. OP wrote

I can't actually set the time because I'm limited to moving at whatever rate/direction the escapement lets me. 

If we replace 'direction' with 'clockwise' that describes perfectly what an hard stuck cannon pinion causes.

Then, we know that on a mov.t that doesn't hack, setting time counterclockwise is not recommended, but personally I still have to see escapement damage caused by that.

[jdm]

1 hour ago, Inumo said:

Google has a lot of advice 

I whish that Google knew everything, it's not so. Books, videos and this forum come closer. Anyway, there are at least a couple of ways of loosening a cannon pinion, one is to squeeze a bit on the notch while it is fitted on the minute wheel, counterintuitive perhaps but it works. Another is gently using a broach on its bore.

 

[watchweasol]

I think the tie has come to establish a few facts, So the problem still exist where the hand setting involves the gear train. So lets go back to basics, remove the balance, fork and gear train then with the center wheel with canon pinion fitted hour wheel and min wheel. Now when tried does it still act the same way with just the minimum of components fitted. when pulled out to the set position the clutch moves and disengeges the wind and engages the handset,which is now still hard to turn (CW) if so remove hour wheel and canon pinion and try now, turns ok /still stiff  if ok the canon pinion is too tight  if still stiff the problem lies elsewhere. If the canon pinion is too tight it will need broaching to free it off somewhat, (jdm has just come back with the same answer mid post) so for now we will leave it there and await further developments.

[Inumo]

I suspect I just realized some of the problem: I've been mistakenly calling the center wheel the minute wheel, because in my head it's "the wheel that maintains the minute time" (even though the cannon pinion is what's actually holding the minute hand, and the minute wheel is the step that connects the cannon pinion to the hour wheel). Anyways. I tried to go through the diagnostic watchweasol suggested, but I keep forgetting how much of a pain replacing the gear train is for me. I'll report back once I actually have new information, but at the very least I know the cannon pinion can turn the center wheel, and I *think* if I get everything reassembled properly it'll turn all the way to the escapement just fine; not sure though, my best attempt somehow let me manually turn the fourth wheel fine to turn the escapement & third wheel, but things stuck when I tried to turn the center wheel manually or via the crown/cannon pinion. Hopefully I didn't damage any parts in all my digging around. :S Assuming everything goes OK there, I'll give pinching the cannon pinion a try once the rest of this system is reassembled & confirmed back to "works fine but grips everything too tight." Worst case scenario, I've got a spare center wheel and cannon pinion from an old tongji movement where the third wheel's pinion broke, so I can try swapping those in. And of course *absolute* worst case scenario I can just buy another movement; these things are, after all, quite cheap.

[watchweasol]

Hi Find attached a document which desinated each component of a watch and it location. Understanding the anatomy of the watch goes a log way when explaining faults thats why we like pictures in addition to highlight problems good luck, await your reports.    cheers

TZIllustratedGlossary.pdf

[Klassiker]

The whole TZ article on the motion works is worth a read*: https://www.timezone.com/2002/09/16/the-motion-works/

(* anything by Walt Odets is worth a read)

[Inumo]

Hokay, last post from me on this one, 'cuz I'm giving up on this movement and buying another replacement. While doing the diagnostic watchweasol suggested, it seems I clumsily bent the third wheel, and now it periodically skips when it disengages with the fourth wheel. Unfortunately, the third wheel's also the one part I don't have a spare of (it was the original broken part in the movement I was replacing), though admittedly I've also broken a couple extra parts in the process of all this. >.> It also seems like something funky's going on with the balance wheel–pallet fork–escape wheel combo, 'cuz the pallets keep getting stuck on the escape wheel's teeth. If I had to guess, the hairspring seems like it's no longer transmitting enough force to get everything to move properly, and/or this particular chassis placed the pallet fork and the escape wheel too closely together, because mass manufacture movement w/ bad QA. To at least test the mystery of the cannon pinion, I gave the pinion a few pinches along the center & top to see if that'd sufficiently reduce friction; it helped some, to be sure, but it didn't completely fix the issue, so I suspect I'd have to broach it to properly fix it (and I am currently feeling too cheap to get broaches this early into the hobby, especially when I'm not 100% sure what size(s) I'd need).

That all said, thank you for the attempts at helping, and extra thanks for the reference materials! watchweasol, I appreciate having such a thorough reference for part names handy; I'd been getting by with Googling "watch movement parts," but this is much more convenient. Klassiker, the article you linked was very handy in understanding how the cannon pinion interfaces with the center wheel & what I should be looking for w/ the notch the others mentioned; much easier to spot now that I've seen the cutaway of it all fitting together. Hopefully I'll be able to manage my watch repairs well enough going forward, but I suspect I'll be seeing y'all around.