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Endeavor

Help please with repair Chrono sec. recorder hand.

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One thing these old Soviet chronograph hands are good at, is stripping off their riveted pipe-bushing after having been 30 years (or more) stuck on a pivot. Not all of them do, but regardless how careful you are, it certainly happens more often than you wish for.

So, this original chrono seconds recorder hand is not an exception. The problem is however, that the original hands are very hard to find, apart from another set with a whole other ($$$) chronograph attached to them.

There are modern substitutes for these hands, but they are a poor copy / wrong shape of the real. Often you can press the hand back on the stripped bushing and with a 45 degrees point  carefully rivet them back on, however I wasn't that lucky with this one. Using a pin-vice I deformed the old soft pipe-bushing and subsequent repair attempt made things only worse, to the point of a non-salvageable pipe-bushing .

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Now at least two years later, I decided to give it another attempt to repair the original hand. To get to a "new" pipe-bushing I scarified one of the modern hands.  The "new"-bushing had to be carefully knocked out, hoping to recover as much of the riveted edge as possible.

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In order to fit the original hand onto the "new" 0.45mm pipe bushing with its "used" riveted edge, I had to enlarge the hole in the original hand to 0.5mm. The original hand "clicked" over the riveted edge, but sadly there is not enough material protruding to create a new rivet edge.

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It didn't take a lot of "force" for the bushing to drop out again.

The nature of this game is such that with these fragile materials and fine edges, one doesn't have many "attempts" to get it right. Now knowing that "riveting" does not provide enough strength (there is simple not enough material protruding to do so), another solution has to be found.

The current status is that I managed to get the pipe-bushing back on, it sits straight and square to the hand.

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Bottom view;

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Top view; as you can see the material barely makes it to the top of the hand.

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Most likely the pipe bushing is a copper alloy and the hand is made of "steel".

Now the question is; who has a brilliant idea, which works (preferable somebody who has been in the same situation before), to connect these two metals?

I would love to hear your suggestions :)

 

Edited by Endeavor

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The paint was "blemished" during a previous "soft"-solder attempt. First I applied some S39 followed by heating up a small amount of fine grains of "soft"-solder to about 350 degrees C melting the solder. The solder sticked to the pipe-bushing but not to the metal. Today I sanded the blemished paint off; the paint is of my least concerns, there is plenty of the "correct"-red available :)

I'm afraid by using "hard"-solder, using an open flame, that it may vaporize the whole lot ......:o It's very hard to judge the temperature of an open-flame hand held burner.

I scarified already a new hand and obviously the original can't take endlessly "abuse" , so before I do anything the next applied method has to be controllable and with a high degree of suc6 ....

Edited by Endeavor

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Hi  If using the super glue method buy the cheap stuff from the pound shop pound for five tubes its thin. Or using the domed end of a staking tool punch and closing the hole on to the bush then lightly flatten the protruding bush metal with a flat punch, 

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UV cure glue, also known as Loca glue, or even UV cure nail polish would be my suggestion.


The advantage of these glues, is they stay liquid till hit with a UV curing lamp, so if you use too much, or for example fill the tube by mistake,  you can remove the excess, check you have it right, *then* hit it with the UV torch.

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55 minutes ago, rodabod said:

There are versions of Loctite which would work better than superglue in my opinion. Or Araldite even.

In a way I like the idea of a none-heating, not touching to apply, binding method. Superglue sounds good but I'm a bit afraid of not having enough time to apply it nicely and thinly. If one could dilute it so it flows better and buys you time, that would be something....

@rodabodWhich type(s) of Loctite are you recommending? I do have some "soft"-Loctite (243), the one which doesn't need heating to undo, but that wouldn't do I guess. Would the one(s) you are recommending flow nicely thin around the joint, creep in the "cracks" and form like solid a "glass" layer? Obviously I don't want to unseat the bushing to get it in between the joint.

Like what @AndyHull just mentioned, a type of glue which buys time and were one has (more) control over the thickness and it's curing time.

Either one has to cure "glass-hard" and not stay "soft" or semi-hard. "Nail polish" doesn't sound convincing enough to me, however I never tried how hard/solid that becomes.

I don't mind ordering & waiting from something that does the trick ..... this "project" has been hanging over my head for a long time. Now it seems that I have a chance of suc6 and therefor I don't mind waiting another few weeks to get or search for the right stuff / binding method .....

Anyway, thanks already for the good tips. I feel a solutions sits in the pipe-line .... :)

Edited by Endeavor

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50 minutes ago, Endeavor said:

@rodabodWhich type(s) of Loctite are you recommending? I do have some "soft"-Loctite (243), the one which doesn't need heating to undo, but that wouldn't do I guess. Would the one(s) you are recommending flow nicely thin around the joint, creep in the "cracks" and form like solid a "glass" layer? Obviously I don't want to unseat the bushing to get it in between the joint.

I recently used Loctite 603 for some watch repairs as it was recommended by the BHI for attaching wheels to arbors instead of soldering. I believe there may be an even stronger version.

https://www.henkel-adhesives.com/uk/en/product/retaining-compounds/loctite_603.html

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Both ideas; UV cure epoxies and Loctite seem quite good. Looking at the tech-sheets it seems to me that Loctite has a lower viscosity (150 cP vs 450 cP for the lowest epoxy in AnyHulls link) and has a more than long enough (for me) working time (https://tdsna.henkel.com/americas/na/adhesives/hnauttds.nsf/web/4A89537CE4638581882571870000D851/$File/603-EN.pdf).

Then again, these UV glues seem to come in small quantities and at low cost. Loctite comes in 50ml bottles, more expensive, limited shelf-live but recommended by BHI  ....what is wisdom ? :huh: Decisions, decisions and decisions ......

I will further investigate both ideas and see which one will do the trick and is the most cost-effective.

Thanks for all the help so far :thumbsu:

Edited by Endeavor

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The only issue I can see with using UV adhesives (apart from not having great experiences with it personally) is that I'm not sure that the UV will penetrate into the adhesive if it is already an interference fit.

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5 minutes ago, rodabod said:

The only issue I can see with using UV adhesives (apart from not having great experiences with it personally) is that I'm not sure that the UV will penetrate into the adhesive if it is already an interference fit.

That's perhaps another one. Reading the Loctite tech-sheet the Loctite will cure regardless.

What is your experience working with Loctite 603?  Do you think I would be able to apply a nice thin layer around the seem of the 0.45mm bushing with say; an old oiler? Another thing with the Loctite is that it seems to provide a good bondage even when 100% clean surfaces can not be guaranteed ........

Perhaps one of those; you get were you pay for ..... ?

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I've been searching the internet and came across Loctite 648. One of Its application is to hold gears & sprockets to gearbox shafts. A 50ml bottle, from China, cost £3.57. The Loctite 243 bottle which I own, also ordered from China, was well within the BBD.

The 648 is a high strength, has a bit higher viscosity but with ample curing time, up to 10 minutes before it starts to set. This should give me the opportunity to apply or remove where and when required before the setting occurs.

If it is capable of holding gears/sprocket to gearbox shafts, surely it will hold a needle to a bushing .....

https://tdsna.henkel.com/americas/na/adhesives/hnauttds.nsf/web/1716575D28E43176882571870000D860/$File/648-EN.pdf

The shipping time China-Denmark will be about 1.5 months (perhaps longer in the coming months?) and as soon as I've glued the bushing to the needle I'll report my finding back to you ;)

I think some very good ideas were brought forward, ideas which may very well do the job.

So thank you very much for you help :thumbsu:

 
Edited by Endeavor

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16 hours ago, Endeavor said:

That's perhaps another one. Reading the Loctite tech-sheet the Loctite will cure regardless.

What is your experience working with Loctite 603?  Do you think I would be able to apply a nice thin layer around the seem of the 0.45mm bushing with say; an old oiler? Another thing with the Loctite is that it seems to provide a good bondage even when 100% clean surfaces can not be guaranteed ........

Perhaps one of those; you get were you pay for ..... ?

I can't remember using 603. I use 243 occasionally for some crowns when they do not have a very strong friction fit. Even that is pretty strong.

If I were you, I'd try the stuff you have already. For application, I usually use a needle or oiler. I apply too much, and then wipe away the excess with tissue paper.

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Loctite 648 is very good, and will indeed hold a gear on an arbor. But it needs a certain amount of surface area. I can pretty much assure it won't hold a sweep seconds hand on a pipe.

Honestly aside from making a new pipe, solder is the best route. You'll want a good flux, it will get it to flow and hold to the steel hand. Tix is a brand of soft solder and flux that will 100% sure work with steel and brass alloys. I have good luck with regular electrical solder and flux too. I heat the assembled hand and tube on a little brass plate over an alcohol lamp. Put flux and a tiny piece of solder at the joint.

Since you're already repainting the heat is a non issue.

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56 minutes ago, nickelsilver said:

Loctite 648 is very good, and will indeed hold a gear on an arbor. But it needs a certain amount of surface area. I can pretty much assure it won't hold a sweep seconds hand on a pipe.

Honestly aside from making a new pipe, solder is the best route. You'll want a good flux, it will get it to flow and hold to the steel hand. Tix is a brand of soft solder and flux that will 100% sure work with steel and brass alloys. I have good luck with regular electrical solder and flux too. I heat the assembled hand and tube on a little brass plate over an alcohol lamp. Put flux and a tiny piece of solder at the joint.

Since you're already repainting the heat is a non issue.

As you have read, I've tried soldering, admitting not using "Tix",  without suc6. The Loctite 648 has been ordered. In order to increase the contact surface area, I may have to reconsider to take the bushing out, apply the Loctite and insert the bushing again. It all depends how time/setting-time & fianl strength test-trials with the Loctite will perform.

I'll de-grease the joint first with brake-cleaner; thanks ;-)

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The thing with the loctite 648 is it needs to be in contact intimately between two surfaces, but an interference fit will squeeze it out. Any exposed loctite will simply sit there wet, doing nothing.

I know you tried soldering before, I'm saying it can work and is worth another shot.

The loctite will come in handy for other things like a sloppy fit case tube or chrono pusher.

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I think you can get surprisingly strong joints with loctite when it is prepared correctly. Some of the formulas have a sheer strength greater than that of Araldite. A good example of that sheer strength (over a massively greater surface area) for me was when I managed to rotate my entire watchmaking bench when twisting a 1cm brass bar glued with Araldite to a seized case back. My loaded bench probably weighs around 100Kg.

Another thing worth mentioning, when you come to re-fit this hand, I would use a flat-ended punch/pusher rather than one with a hole in it. That may seem obvious, but I sometimes use the same punch/pusher that I use for the minute hand as I do for the sweep seconds hand, where applicable.

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Thank you all for thinking along with me ;)

I'll first try Loctite as that feels & seems to me a less intrusive and a very valid option. If that were to fail, an attempt to solder the joint can still be done. The other way around seems less attractive to me. Soldering is still a good option provided, just like with the Loctite, we were to get a proper surface bondage. Loctite doesn't seem to have an issue with different material or surfaces. Unknown to me are the long term behavior of Loctite, from soldered joints we are all well aware of the fatigue problems.  

I'll report back with my findings :)

 

 

Edited by Endeavor

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