Stop start issues, Raketa 2628H

[Sberry]

I bought a couple of nonfunctional Raketa 2628 watches from ebay a few months ago to learn on and I was able to cobble together on working watch that looks and performs pretty well. I'm pleased with it. Took it fully apart, cleaned, oiled assembled. Reasonably decent job and I didn't notice anything janky testing assemblies along the way.

I did not replace the mainspring - I don't have a winder and my attempts to do this by hand have been ape-like and damaging. I cracked it open and inspected it and it wasn't visibly filthy.

The balance from watch movement #1 was bad, so I moved over the balance from watch movement 2. It ticks happily (to my ear) and shows good accuracy and amplitude. I have not futzed with the beat error yet.

The only issue is that it periodically stops for no reason even with a lot of wind left in the mainspring. I can manually try to get it started again by nudging the balance but it doesn't seem to want to go. However, If I pull the crown to hand-setting position it will fire right up, and continue to run after I push it back in. This may be a red-herring and I'm trying to let it run on the bench and keep a log of it to see if there is a pattern.

It runs well consistently, for hours, until it doesn't.

Throwing it out there to see if anyone has an idea for better-diagnosing.

Steve

Austin , TX

 

[Sberry]

Here's a backup link to a video of the watch running, in case the one I embedded in the post doesn't work

 

[Sberry]

More info - just stopped again after running for 2 hours. Nudging the balance it will move at very low amplitude for a moment and then stop. Tried several times, it's not frozen, the motion works will move, it just seems like there is intermittent resistance somewhere in the system that can't be overcome.

This time I pulled the setting lever to hand-setting position and nothing happened. I then turn the hand setting lever, and click it back to wind position, and it fires right up with good amplitude.

I do think, based on this, that the balance and mainspring are OK. I'm still a novice - this is like the 3rd movement I've really dug into.

My next thought is to pull of the date complication stuff and see if it runs for a full day without it. Then maybe do the same with Cannon pinion removed.

[watchweasol]

1. Hi and welcome to the forum.       When it next stops  try to remove the balance assy and take a look at the pallet/fork and check it moves smartly from banking pin to pin, If not you still may have a problem with the mainspring sticking in the barrel, worth checking pivots and jewels for wear and or cracks.  When you cleaned it what was it with ?  

[watchweasol]

HI   tech sheet for raketa attached might be usefull some time 

Raketa 2628 (1).pdf

[VWatchie]

Always hard so make a guess... Anyway, I think the problem is on the dial side, i.e. the dial train (cannon pinion, minute wheel, hour wheel, intermediate wheel). Could it be that the clutch wheel doesn't disengage properly from the intermediate wheel that drives the minute wheel when you set the time? If so the intermediate wheel may bind up the minute wheel making things slow down and then stop. Well, just guessing. Anyway, I'd check the dial train (motion works) and the keyless works. I think your idea of removing the cannon pinion to see if it solves the problem is a good idea. If it doesn't help you'll know for sure the problem is with the train of wheels or the escapement.

Good luck and let us know of any progress or any new observations.

[Sberry]

I cleaned it by soaking in Home Depot naptha and pegging by hand, 2 rinses. Demagnetized the whole thing, as well. I'll dig back in with both suggestions and report back any findings.

Enjoying the process.

[AndyHull]

In my experience the most likely cause is dirt, and most likely dirt that has migrated from the keyless work.

Next most likely is dried oil.

Both would respond to a good soak in naptha, but you will need to re-oil afterwards as naptha will tend to remove any lubrication. Running without oiling will cause more problems.

[Nucejoe]

Eliminating process best start at canon pinion, next suspect is the barrel, check if lid is fully pressed in and sits level,it can rub on bridge. Check holes the arbor go in may be worn etc. Another common cause is fault in gear train.

[Sberry]

Removed cannon pinion and it ran all night - good!

When I nudged the minute wheel around with tweezers, or even spinning with crown, I could feel some resistance at one point in the revolution where it feels stickier than at other parts. Pulled off the calendar plate and notice that the intermediate wheel had a bit of junk on the gear teeth and was over-oiled, sticking to the plate. Cleaned it up and put it back in, reinstalled the calendar plate which is held in with 3 tiny screws. If I torque them, the intermediate wheel seems to drag. Loosening the screws to minimum clamping torque allows it to spin freely. Leaving it like this for another day to confirm that it fixes it.