condition of jewels????

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  • #48421
    watchthebear
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    • Topics Started: 21
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    Hello folks, hope all are well. Another problem that I haven’t seen a good explanation for. Anyway I want your experience and advice. How does one judge the condition of press-fitted jewels in plates and bridges? I know the center wheel usually has some sort of metal cap or a “cap Jewell” (don’t know the correct name) But I find the jewels for the 3rd, 4th, and escape wheels in all sorts of shape. When is the jewel something that is affecting the running of the movement? Is it ok if the pivot sticks a tiny bit through the underside? what about more? sometimes the underside feels flat to the touch w/ a piece of peg wood, a basting pin, and a finger tip. some times there is a sharp feeling, and , of course, sometimes the pivot is almost made it’s way through and that is pretty obviously a big problem. I am a slow learner so i have taken apart about 75 non-working watches so far; and I have seen all sorts of stuff that went wrong. The jewels are hard to tell when the movement is still together, and once the bridges are removed for inspection it’s hard to determine if one or more are a problem. Any and all thoughts appreciated. take care all……….thanks…………b

    #52423
    david pierce
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    • Topics Started: 90
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    Watchthebear,
    The holes in the jewels and the pinions must be cylindrical. Any geometry other than this will cause problems. Any chips or cracks in the jewels are a problem. The cylindrical portion of the pinion must be the only thing that rides in the cylindrical hole in the jewel. A cracked or chipped jewel can cut into the pinion and cause it to wear in an uneven fashion. The best way to spot these issues is with a microscope.
    david

    #52424
    watchthebear
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    • Topics Started: 21
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    Hi folks, thanks for the input David. Any other comments? I am particularly interested in what can be learned by the condition of the backside of the jewel. It seems to run the whole gamut. The simplest question I can ask is: shoud there be any penetration of the pivot or pinion cylinder through the back side? It would make it easier, when going through broken watches, if I had some idea of the first signs that a jewel is bad and needs replacement. I am probably not articulating this well, but I think I have given a general idea of what i am perplexed about. take care and stay well all……………………..b

    #52425
    willofiam
    Moderator
    • Topics Started: 75
    • Total Posts: 1437

    Hey b, I am in the learning process also, likely for the rest of my life!!! 🙄 I am under the impression that a jewel hole is put in to be able to withstand wear by a steel pivot. the jewel will usually not be the culprit but the pivot will as it is most likely to be worn. On the other hand pivot holes that are not jeweled would be subject to more wear but treated similarly for fit as the jeweled hole. one thing I can think of on this is to check the end shake and side shake of any given wheel pivot. I think anything more than 5 degrees side shake is too much, and the end shake should not be much at all yet perceptible. As David mentions, chips or cracks in the jewel is a issue and should be replaced as they will cause alot of wear. BUT if I understand your question, @watchthebear wrote:

    The simplest question I can ask is: shoud there be any penetration of the pivot or pinion cylinder through the back side?

    Checking the end and side shake would most likely let you know if you had a bad or worn pivot…..and this would be why is would stick out the plate more than others……A good book I am reading thru is the “practical watch repairing, by Donald de Carle” I do have another book on its way (I will wait to mention it until I get it) and guys on here have mention other books that are really good, explaining how to inspect a watch as you go thru it. I hope someone with more knowledge chimes in and sets us straight :D , Have a great day, William

    #52426
    watchthebear
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    • Topics Started: 21
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    Good afternoon all (10:45 PST), thanks willofiam for another view. I have worn out many of the chapters of de Carle’s book (except the parts that deal w/ machines). Even his short section on pressed fit jewels was not helbful and the drawing was confusing. I’ll give an example: I have a watch–17 jewels–I’m looking at the various bridges etc. and seeing about 5-6 jewels. the balance pivot has an end jewel so that doesn’t count. The center wheel has a special provision made for it (usually on all but the cheapest of watches i see), now there are the rest of the jewels. one has enough of a whole in the jewel that the shaft that the wheel is on is sticking through enough that you could scratch your finger if you tried. another has enough through that you can feel it if you rub very gently w/ a piece of pick wood. another is smooth, but you can see, under 10X, a little speck of an indention where it looks like the shaft is intended to come through (how could this be so?). and there is one jewel that is totally smooth on the bottom. All 4 of these jewels appear the same from the top. I have been taking these bridges off and throwing them in a box. I don’t think anyone would care to see so many pix, but i want them to go back and refer to. This jewel problem (?) almost always occurs when the balance looks good, I can manually turn the great wheel and the center wheel responds, but when i turn the center wheel the train “bunches up” so the escape wheel won’t turn. This occurs w/ the balance and pallet in, or removed. Once in a while , everything runs nicely when i remove the balance and the pallet. I usually find that the pallet has gone bad–a couple times it had no jewels, another time only one, and another couple times one pallet jewel was just sort of hanging there. Early in William James’ “Varieties of religious Experience” he speaks about discussions they would have in various homes on Sundays and how at least one of the participants would vow to “stay until we have thrashed the truth out of this matter”. That is the way I feel about this and many other watch problems that come up so regularly. Take care all……….thanks……………………….b

    #52427
    david pierce
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    • Topics Started: 90
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    Watchthebear,
    Remember, there must be a cylindrical shaft rotating in a cylindrical hole. Anything else will be a problem. if part of the pivot is protruding too far out of the jewel hole, it might mean that either the lower or upper jewel was pressed in too far and the shoulder of the staff is rubbing on the bottom of the jewel. Jeweling tools (Seitz) have micrometer stops on them to properly depth the jewels in the bridge and pilar holes. The balance staff can introduce two additional problems due to cap jewels pushing on the pivots. To troubleshoot, remove the gears and add them back in one at a time starting with the 2nd wheel. Rotate the assembly with a small sewing needle or similar tool and add the gears back into the train in sequence (3rd, 4th, 5th). When there is resistance, that will be where the problem lies.
    david

    #52428
    watchthebear
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    • Topics Started: 21
    • Total Posts: 77

    Good morning all, thanks for the ideas David, I will add the troubleshooting advice to my list of things to try when I am confused and don’t see any clear answer to the trouble, which is 9 times out of 10. Here is one more case: I remove the balance cock and wheel, then I try to run the train manually. Sometimes the pallet fork moves back and forth, other times it appears “stuck” . So, I remove the pallet assembly and sometimes the escape wheel now turns freely, sometimes it “bucks up” when I try to run the train. Is the first place where the train gets stuck the culprit, or is the trouble someplace else and I just don’t understand what is going on? This one really gets me. One thing i have realized is that i am trying to trouble shoot 17 jewel movements, but they are very cheap 17 jewel watches. Some are pin-levers, which I junk, others are about the quality of dollar watches (part by part) but are just designed to appear to be of higher quality. Bob mentioned that better quality watches are usually (or often) more repair friendly; I was wondering if it might be well to hunt down good quality non-working watches to learn on. One last comment before this becomes a short story: I have taken apart several good quality working watches, and reassembled them. At present, my interest is something of a forensic nature. The idea of taking something that doesn’t work, diagnosing the problem, and fixing it if it is realistic from a time and money point of view, has really grabbed a hold of me. thanks all for past and future input.take care……….b

    #52429
    david pierce
    Participant
    • Topics Started: 90
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    Watchthebear,
    You really should buy a microscope. A microscope with sufficient quality to do watch work is surprisingly inexpensive. They are particularly helpful putting the pilar plates and bridges back into place and making sure that all of the pivots are lined up with the jewel holes before squeezing the plates together. They also allow you to get a better look at the individual watch parts. Don’t be impressed with a designer label on a watch. You will be suprised at how crude gears and pinions look on both inexpensive and expensive watches. The precision of a watch gear is far below the precision of a gear out of a car transmission. This is due to the fact that torque loads on watch gears is extremely low and ultra precision is not of great relevance to the longivity of the machine. Automobile transmission gears are hobbed, hardened, tempered, ground and then lapped to an extremely high degree of precision. If they were not done this way they would not last long. Watch gears, on the other hand, can be stamped from a soft metal in a punch press, and the watch will function quite well. If you disassemble a watch and reassemble it and the gear train does not turn properly, one of the pivots is probably not in the jewel hole. A microscope will help you avoid this.
    david

    #52430
    watchthebear
    Participant
    • Topics Started: 21
    • Total Posts: 77

    Hi all, thanks David. I have a very high quality binocular microscope w/ the light staging and all that stuff. I never thought of using it because it seems like there would be no way to see what i was working on (when i wanted to look at the work w/out the increased size). In short, I have never tried it. Maybe I should give it a spin. thanks again……….take care all……………….b

    #52431
    david pierce
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    • Topics Started: 90
    • Total Posts: 1360

    Watchthebear,
    The microscope I use is called an Amscope. It is binocular dual power (20x and 40x) selectable with a rotating turret. The eyepieces were shipped mounted backwards for packing purposes and I had to disassemble it and reverse the eyepieces and the prisms. The eyepieces must be positioned so the front of the microscope is facing you when you are looking through it. Once you start using it you will be amazed how much better the view is. For more general work I use high power drugstore reading glasses. I still occasionally use loupes but not often.
    david

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watchthebearcondition of jewels????