Erratic seconds hand x2

[Davey57]

I posted a question a little while back regarding erratic seconds hand, see here

Luckily I managed to find another watch with the exact same movement with a full set of hands and in working order. It arrived and was running, although very sluggish, but the main thing was that the seconds hand moved nice and smoothly so I had something to work with. The first thing I tried was putting the seconds hand on my movement, the jumping and slight hesitation remained. Next step was to begin transferring some parts onto my watch hoping to find the problem. As soon as I removed the bridge I thought, bingo! This must be why my watch is behaving like it does. Underneath the pinion that the seconds hand is mounted to there was a very thin shim, presumably to allow it to turn smoothly.  Here’s a picture

I fitted the shim along with the pinion,  bridge back on and, still the same. I then swapped the next wheel in the train from the donor, still the same. At this point I assumed that the problem still lay further down the line somewhere in my watch, but just to confirm I put the parts already removed from my movement back into the donor watch. Logically, I thought that would confirm those parts were ok if the donor still ticked ok, it didn’t. Before I went any further I put all the original parts back into the previously nice running donor and now that one is behaving  the same as mine. I have no idea what has happened. I am going back to square one. I have stripped mine back down again, brushed all of the wheels and pinions in case some debris is still lurking between the teeth and at the moment they are soaking in lighter fluid. 

I was watching the hand moving on the donor movement trying to see any clues as to what might be happening. When the hand stutters and sometimes completely stops the watch itself seems unaffected and continues running ok apparently. I was surprised to find that if I actually block the seconds hand, the balance continues to swing and the train can move a little before it stops. So if something is temporarily blocking the train somewhere it’s not enough to stop it, just enough to make the seconds hand jump. I was thinking maybe one of the wheels might have a tight spot or something, I don’t know really. I’m just going to clean it all up again thoroughly, build it up without the pallet or balance, fit the second hand and see how it moves in that state. It just seems odd that I have somehow managed to introduce the same problem onto the other movement. The only other time I have seen a second hand jump like this was on a Seiko 4205, but that is a recognised problem with them. They have a tension spring but it doesn’t always work and it’s something you have to put up with. I’d certainly appreciate any advice.

Thanks.

[Nucejoe]

If you remove the seconds arbor, you would find the movement runing fine on wrist and on timegrapher. The culprit and it is a culprit, is: at the  pinion end of the arbor. A shim or tension spring is to keep the pinion in proper contact with the min wheel, improper oiling of the shim-pinion is the likely cause.

[Davey57]

I’ve been looking at the shim while the watch is running. It does not touch the pinion at all it is just sitting beneath it. Annoyingly,  I did not observe it’s position before I stripped it out, I did not know it would be there otherwise I would have done. The only way I can see it exerting any tension onto the pinion is if it was shaped like a dial washer and sprung up slightly. Should it be this shape? When it was out it was all a bit wrinkled so I flattened it out. I am wondering what I could use as a replacement, I don’t imagine I will find a dial washer that small. Where to oil and where not to oil then Joe?

Thanks

Edited June 4, 2019 by Davey57

[watchweasol]

Hi Davey  My approach would be to assemble just the pinnion and its adjacent gear/wheel and rolate the wheel with a fine brush feeling for any sticky point if none add the next wheel and repeat untill the cuprit is found, it is possible that you have wheel out of round. I have attached the tech sheets for the 4205.

4616_seiko 4205A.pdf 286_Seiko4205B,4206B,4207B.pdf

[Nucejoe]

Hi Davey, The video wont open. Please give caliber.

Check side shake on the min arbor, you have access to the min wheel ( broken jewel) , if removed/ replaced the min wheel may develope the babbit to slip on its arbor.

Both faces of the pinion gear should be lubed and interface with smooth surfaces (  stone jewel or metal) 

Seconds arbor may rub inside the center tube. Make sure inside of the center tube is clean, Neither seconds arbor look bent, pivot on them may be. 

The tension spring or shim interface should be smooth.

You are right the preveous owner got tired and rid of it.

 

 

 

 

[Davey57]

Thanks, I’ll have another go. Need to have a break from it as it has become a bit obsessive trying to get to the bottom of it. Added to which I have managed to break off the top pivot of the seconds pinion, so annoying. Lucky I have the luxury of the spare. At the moment I am at this stage. I have polished up the arbor for the seconds hand in case it was a bit sticky in the tube. I have fitted the centre wheel, seconds arbor and the wheel that drives its pinion. With the bridge on it all spins freely. I have put the second hand back on and tried pushing it round with a thin bristle from a paintbrush. It all seemed well but a couple of times the second hand jumps ahead of the bristle slightly as if it had just released itself. It is assembled dry at the moment and I have not put in the shim as it is now looking more like it would hinder rather than help.

Thanks for the links watchweasol. It’s not a 4205 by the way  I only mentioned that as a few I have done previously had the same problem.

Sorry, meant to add that it’s a Pallas movement but I’m not sure of the exact calibre.

Edited June 4, 2019 by Davey57
More info.

[watchweasol]

Hi Davey If the wheels spin freely without the second hand on but jump when on as Joe says check the tube ass for rubbing as the extra weight of the hand can exaggerate the problem   good luck

[Davey57]

Ok will do. Thanks for the help

[Nucejoe]

Replacing the shim with a domed stone jewel would enhance the design.  

[Davey57]

That is genius Joe, I like that!  Course, the next question is, will I be able to find a jewel like that with a big enough hole in or would I need a modified one?

[Nucejoe]

I wouldn,t try modifying a jewel hole. We just may find a suitable one in bag of scrap movements.