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  1. #1
    GEDAC
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    Default Dynamic Poising of Balance Wheels

    Somewhere in either the British Horological Journal or your Nawcc literature I have seen a description of this technique which uses a timing machine to identify the out of poise point on a balance which allows careful repoising.(either addition of timing washers or removal of small amounts of weight).
    Please assist me urgently.
    Many thanks from this side of the pond.

  2. #2
    GEDAC
    Guest

    Default Dynamic Poising of Balance Wheels (RE: GEDAC)

    Somewhere in either the British Horological Journal or your Nawcc literature I have seen a description of this technique which uses a timing machine to identify the out of poise point on a balance which allows careful repoising.(either addition of timing washers or removal of small amounts of weight).
    Please assist me urgently.
    Many thanks from this side of the pond.

  3. #3
    Registered User doug sinclair's Avatar
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    Default Dynamic Poising of Balance Wheels (RE: GEDAC)

    GEDAC,

    Please tell us what quality of watch you are dealing with, what condition it is in, and how much of a positional error you are dealing with. Positional error is not always the result of an out-of-poise balance wheel. Have you a poising tool, and have you poised the wheel in question on it? If you have statically tested the wheel and found it to be poised and still have positional error, we need to know this before we try to answer your question.

  4. #4
    Mike Kearney
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    Default Dynamic Poising of Balance Wheels (RE: GEDAC)

    I think gedac is asking for a description of the process or technique called dynamic poising. I have often wondered the same thing. A google search shows that WOSTEP and AWCI mention it in their course descriptions, and it's been mentioned on this board in the past, but we've never had any discussion on what it is or how it differs from plain old poising.

    Regards,
    Mike

  5. #5

    Default Dynamic Poising of Balance Wheels (RE: GEDAC)

    I used to specify and purchase vibration monitoring equipment for gas turbines, aka jet engines, in a previous life.

    dynamic balancing is the black art of spinning a machine or part thereof, measuring the result with instrumentation and then adding/removing material as indicated by the results. Example, tire balancing.

    But, an apparatus capable of doing this on a watch balance is hard to imagine.

  6. #6

    Default Dynamic Poising of Balance Wheels (RE: GEDAC)

    First you true the balance to flat and round. Then you static poise it using a poising tool. Then you true the hairspring flat and round and place it on the balance. Install the balance in the watch.

    Let down the mainspring and notice the relaxed position of the balance. Wind the mainspring until the balance is doing about one turn. Put the watch on a timining machine in the pendant position with the pendant up. Then time it pendant right, down and left. Find the position that gives you the fastest rate. Vary the position clockwise and counter clockwise from this position looking for the fastest rate. In this position, the heavy part of the balance is down (when the balance is at rest). The slowest position will be the opposite position. For example, if the fastest position is 1 o'clock up, then the slowest position will be 7 o'clock up. Here the heaviest part of the balance is up (at rest). You can then add a timing washer opposite to the heavy spot.

    If you wind the watch up so that it is doing about 1 1/2 turns,then everything I have said is the opposite. The fastest rate occures when the heavy spot is up. Positional error is more pronounce for low turns, so I prefer to use it.

    Two warnings. First there are many other causes for positional error. One of the most common is the hairspring is not in the flat or round. If it bulges in one direction, then that will act just like a heavy spot in the balance in that direction. If one branch of the balance ring is bent outward (the balance has not been trued in the round), that too will act like a heavy spot. Do not create a new error in an effort to overcome the real error. You will eventually just compound the problems.

    Second I do not like taking weight off of the timing screws. If I put on a washer, I can always remove it. If I take weight off a balance screw, the balance screw has been altered forever. If I make a mistake, I then have to do more damage to fix it. What a mess.

    There are many books on adjusting a watch at the NAWCC library. I strongly recommend you read one before attempting this.

    One great one is Rules and practice for adjusting watches by Walter Kleinlein It is very old, but outstanding.

    Another more modern text is Watch Adjustment by H. Jendritzki

    Once again, a dynamic adjustment is the FINAL fine tuning of a watch that is running properly in all other respects.

    Don

  7. #7
    Registered User doug sinclair's Avatar
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    Default Dynamic Poising of Balance Wheels (RE: GEDAC)

    Without having received an answer to the questions I asked in my first post, it is difficult to know what to advise.

    The grade of watch may be such that, even with a perfectly poised balance wheel, there may still be positional error. Badly adjusted banking pins can cause a problem because of uneven lock on the pallet stones. Pivot problems as described by Henry Fried in his Watch Repairer's Manual can be a factor. Quality of the watch is occasionally a factor.

    Kleinlein is quite explicit in his book. He states that one watch that is adjusted to five positions might be adjusted to a 25 second tolerance in 24 hours, while another might be adjusted to 5 positions with a 6 second tolerance in 24 hours. These are all to be taken into consideration before you should embark on the task of turning a sow's ear into a silk purse! Assuming it is a sow's ear you are starting out with!

    I have had "dynamic" balancing described to me, relative to a wheel on an automobile in which weights are added both on the outside rim of the wheel, but also on the inner rim of the wheel. The wheel of course being spun at high speed on a machine that can identify where to place the weights, and how much weight to add. I've never heard of a method that would make this possible (or even beneficial) on a watch! I have been wondering whether these modern timing machines such as the Witschi are able to give such information. In any event, with the screwless balance wheels on modern watches, there are not a lot of options as to poising the balance wheel.

  8. #8
    Registered User doug sinclair's Avatar
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    Default Dynamic Poising of Balance Wheels (RE: GEDAC)

    Peter & Don,

    I found this all very interesting. Thanks to both of you. However, I have a question regarding the use of a poising tool for poising a balance wheel. Is it possible that the balance wheel could come off the poising tool still unpoised? When I decide that a balance wheel is poised, I tilt my poising tool just a bit, and give the balance rim a slight rotation in the downhill direction. Only when the wheel will roll completely off the poising tool is it poised. I have always felt that was good enough. But perhaps not?

  9. #9

    Default Dynamic Poising of Balance Wheels (RE: GEDAC)

    Peter, there is no substitute for good equipment. We much prefer high quality poising tools with jeweled knife edges.

    I use a cat's wisker to start the balance rolling with the jaws level. If it stops at the same place each time, it is out of poise.

    I suspect that many people do a fair job of poising the balance, but then find positional errors in the movement due to an unpoised hairspring. They then unpoise the balance in an effort to correct for their neglect or lack of skill in truing the hairspring.

    If you have done a good job poising the balance on a good poising tool, it would be best to use dynamic poising to correct the hairspring, not the balance. On a high grade what, I like to get it within 5 seconds over the pendant positions and 7 seconds over 5 or 6 positions.

    Don

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