American PW New Project...more to learn

Discussion in 'Watch Repair' started by f.webster, Mar 25, 2020.

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  1. f.webster

    f.webster Registered User
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    Dec 18, 2009
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    While I am staying home, I am pulling out "projects" that I can work on...and learn from doing.

    This project watch is a Hampden, Dueber Grand/ model 3, 18s, 17 jewel open face from about 1899.

    After letting the power down I removed the balance screw and bridge. The bridge came off and left the hairspring and balance wheel behind. Closer inspection revealed that the stud on the end of the hairspring was no longer attached. Nuts!

    Here is where my new learning begins.

    Is there a right way to reattach the stud to the hairspring?
    Do hairsprings come with the stud attached...should I be looking for a anew hairspring?

    Please help with your wise counsel and experiences in this type situation.

    20200325_120843.jpg 20200325_120931.jpg 20200325_123429.jpg
     
  2. 179

    179 Registered User
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    Frank, It will most likely need to be replaced. If it is broken off, as opposed to unpinned, if you repin it will be too short. This will affect the timing. Check the stud and see if the end and pin are in it.
     
  3. Skutt50

    Skutt50 Registered User

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    If you can find a replacement hairspring it is not certain it will keep time with the old balance. The two are tuned to match one another to give the correct beats per hour.

    If the breakage is next to the stud you could try to re attach the hairspring, adjust the collet to get the beat error down and test. You might have to add some timing washers or accept that the regulating arm is close to one of its end positions. Even if it will not be a perfect repair you will learn a lot, and everything is reversable, should someone in the future whish to restore it to its original stage.

    The hairspring is attached to the stud with a small taperd brass pin. You need to push the pin out and preferably replace. The old is usually very short and may be difficult to reinstal.
     
  4. Rob P.

    Rob P. Registered User

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    #4 Rob P., Mar 25, 2020
    Last edited: Mar 25, 2020
    Just did this again on a 0 size Elgin yesterday. Its really labor intensive but you can repin the HS on the stud if you have enough magnification and fine tipped tweezers.

    You'll need a new brass taper pin. If you don't have one small enough, you'll need to file one down until it fits the hole in the stud. Next, put the stud into the balance bridge. If the stud is round rather than triangular, it MUST go in the bridge correct way - the hole in the stud is usually offset to 1 side. Run the regulator all the way toward the stud and look to see which orientation is closest to alignment with the pins. You'll also need to see which side of the hole the spring should go against when you stick the pin in there. You want as straight a shot from the stud to the pins as you can get.

    Put the balance bridge upside down and stick it down so it doesn't move around on you. I use a blob of rodico to hold it in place. Try to keep the rodico away from the HS because it's a mess if it gets in the coils and it's a pain to remove.

    Carefully thread the end of the HS through the hole in the stud. You don't want any HS sticking out the other side. Flush with the end of the hole is ok but no further. Now, carefully push the taper pin in place.being sure you don't shove more of the HS through the hole as the pin goes in AND that the HS is on the "proper" side of the hole. Using a sharp screwdriver, press the tip of the screwdriver onto the pin and bend the tail end of the pin. You don't need to use brute strength, just good solid pressure with the screwdriver to hold the pin in place as you bend it. It will break off at the point the screwdriver is pressing on it. Don't slip or you'll likely snap the HS off. It'll be inevitable no matter what you do to try and avoid it.

    Once the pin is in, center the HS over the hole jewel and ensure that the pins are on the terminal curve and that the HS doesn't move when you run the regulator from F to S. Adjust as necessary.

    The balance has (or should have) a mark on the rim where the stud should point to. If it doesn't put the balance into the movement and drop the bridge on it. Rotate the balance so the impulse jewel centers the fork between the banking pins and hold it there while you use a sharpie to mark the rim where the stud hole in the bridge is. Once you know where the stud orientates on the rim install the HS onto the balance. I do this on my staking tool with a flat nosed hollow stake. Under magnification I can see if the stud is where it needs to go. If it needs tweaked I can do that easily enough. Once it's where I want it I just press it down with the stake. Reattach the assembly to the balance bridge.

    Test in the timing machine for the rate. If the HS was broken it'll be shorter and the rate will be fast. Depending on how much faster will determine how you slow it down. 300 beats is 1 minute and you can use timing washers for that. If it's trying to set the land speed record, you'll need to add mass to the balance rim by adding additional timing screws. If you have or can find a similar sized / same maker balance, you can steal opposing pairs of screws and install them in your balance. You'll need to remove the HS and poise the balance if you do this.

    Retest and adjust with more mass/washers (or undercutting if it's now too heavy) as necessary. It takes me a few hours to do this from start to finish if everything goes well. If things don't go well, 7 hours is about my worst time for this particular task.

    If it's too slow, you can loosen the taper pin with the tweezers and push some more of the HS through the stud rather than lighten the balance. Worst comes to worst and you lose the pin that's in there, you'll need to use / make a new pin. No big deal.

    Test, adjust, and retest until the regulator is in the middle of the scale. You can get it pretty darn exact if you really want to. BTW, buying a HS and sticking it onto your balance will still result in the same testing / adjusting / retesting process. Tanstaafl.
     
  5. roughbarked

    roughbarked Registered User

    Dec 2, 2016
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    I've never bent a stud pin. Have never seen a watch manufactured with a bent stud pin.
    If all this is too hard and it does take quite a bit of practice, There are other ways.
    In modern watches the hairsprings are attached to the stud with adhesives.
     
  6. Rob P.

    Rob P. Registered User

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    The purpose of bending the taper pin is to break it off rather than leave it in place with the tail sticking out. I admit I don't use the tiny taper pins manufactured for use for HS studs. I just file one of my own out of brass wire and break off the excess.
     
  7. roughbarked

    roughbarked Registered User

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    Fair enough. I simply break or cut my pins off the wire before I fit them.
     
  8. Rob P.

    Rob P. Registered User

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    I have tremors so I prefer working with full sized pin stock and then breaking it off after it's installed in the stud.



    One thing I didn't mention is that if the balance is dynamically poised (adjusted) and you have to add a pair of timing screws, put it on the poising tool before you do anything and mark the rim level with the poising tool jaw with a sharpie. Then when you add the new screws, undercut ONLY THOSE SCREWS as necessary to return the mark level with the poising tool jaw. You won't mess up the dynamic poise that way. Or, at least you shouldn't from what little I understand about dynamic poise.

    You'll have to figure out which one to undercut if the mark isn't level with the jaw after adding the screws. Basically if the mark is high and the screws are at 2 and 8 in relation to the mark, undercut the lower screw. If "lower" at 2 and 8, undercut the the upper screw. If higher at 10 and 4, undercut the upper screw. If lower at 10 and 4 undercut the lower screw.

    Once you have the poise back to where it was, then you can test and adjust the mass (by adding washers to or undercutting only the new screws) to bring it to time. Only do this to the new screws because you're trying to adjust the extra mass, not change the poise. Always be sure the balance returns to the dynamic poise mark after each adjustment.

    This method worked for me on the 1 dynamically poised balance I so far have had to add mass to. It may not be "the correct way" to do it, but it worked for me.
     
  9. f.webster

    f.webster Registered User
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    … one thing I forget to mention, I am a clock guy who has only just begun tinkering with watches.

    With that said, I don't know if I have the tools to accomplish some of the things talked about above. Today I will see if I can see what you so kindly have described. My magnification is limited.
     
  10. gmorse

    gmorse Registered User
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    Hi Rob,

    That's a pretty good reason, but have you thought of making a small file nick in the pin where you want the end to be, (a little longer than the edge of the stud), and then when you've pressed it home it will break off at the nick, leaving some to grab hold of if you have to take the pin out again.

    Regards,

    Graham
     
  11. Rob P.

    Rob P. Registered User

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    I used to do it that way until I discovered that you can just press on it with a screwdriver tip and it'll break off right where the screwdriver is. With the nick I still sometimes pulled the pin out as I was trying to break it off. The screwdriver holds it in place and makes the nick extraneous.
     
  12. Rob P.

    Rob P. Registered User

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    If you have screwdrivers small enough to disassemble the movement, the only other things you need are magnification and a pair of those splinter tweezers you can get at the drugstore. And eye loup will work although it can strain your eyes.

    The timing part is difficult without a timing machine but it can be done. It just takes forever. One day on fast, one day on slow and record the difference in timekeeping. That will tell you how much to adjust to put the regulator in the middle of the scale. Then adjust and one day fast, one day slow and repeat until it's where you want it.

    You can make a reasonably decent poising tool with 2 single edged razor blades and some Rodico.
     
  13. f.webster

    f.webster Registered User
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    Thanks Rob P. for the heads up on the Hampden parts on ebay. Removing and replacing a hairspring will be easier for me at this stage in my horological development.
     
  14. Rob P.

    Rob P. Registered User

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    You're welcome.
     

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