Query a Bergeon Bushing Machine

Discussion in 'Clock Repair' started by NEW65, Aug 1, 2020.

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  1. NEW65

    NEW65 Registered User

    Nov 17, 2010
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    I just have a query regarding the use of a bergeon bushing machine when used to re bush a centre arbor.
    Firstly, regarding re bushing a centre arbor, there is absolutely no room for error ! Ie., it is absolutely essential that the original hole is located. I know how it important it is for ANY new bushings to be fitted accurately but I feel that there is less room for error when doing the centre arbors.
    My query is that if a bergeon bushing machine is used to re bush a centre arbor and only a fraction of a millimetre of brass has to removed by the reamer, is the bushing machine the best tool for the job?
    Thanks chaps.
     
  2. Jerry Kieffer

    Jerry Kieffer Registered User
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    First, in general , bushing machine use will be more accurate than the normal recommended hand bushing methods.

    The issues with a bushing machine where a high degree of accuracy is desired, is that spindles are often not fitted for a high degree of accuracy. In addition, the effectiveness of the center location accessories require a degree of skill and luck for perfection. Depending on location accuracy, you now typically have loose fitting reamers in the spindle. This is good news and bad news as the reamer floats slightly, it provides the exact desired friction fit for a bushing, but location may not be as intended. While, the bushing machine will generally provide successful bushing in the proper hands, the kind of accuracy you seem to be looking for will be more about luck than predetermined success.

    If you wish to achieve the type of accuracy you are describing, both metal working and location as well as be assured of a predetermined outcome, a milling machine will be your best option.
    It also offers greater value for the money spent in that it can be used for a million things and replaces many other single purpose tools in a shop, not to mention the skill levels it develops.

    Jerry Kieffer
     
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  3. R. Croswell

    R. Croswell Registered User

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    If "only a fraction of a millimetre of brass has to removed by the reamer" it really shouldn't matter whether the reamer is held in a Bergeon, or some other bushing machine or a mill. I don't see the center arbor as being any more or less critical than any other. I'm not sure that I understand your concern about the amount of brass to be removed, which would be the same for a given bushing regardless of how the hole is reamed. I get uncomfortable when very large bushings and pressed into very thin plates. What type of clock are we talking about?

    RC
     
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  4. R&A

    R&A Registered User

    Oct 21, 2008
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    Are you more concerned about the wall thickness of the bushing because you are not taking out much material before installing the bushing ??
     
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  5. wow

    wow Registered User
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    New, I can’t remember the last time I bushed a center arbor bushing. They are hardly ever worn enough to require bushing. There is very little pressure exerted on that hole and a little play is fine usually. Let us know what kind of movement you are working on and post photos of it so we can help you decide whether or not it needs a bushing.
     
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  6. shutterbug

    shutterbug Moderator
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    It's more common to have to bush the center hole in chiming clocks. The work of lifting the arms repeatedly, makes the wear downward on the center hole, and eventually the lift will not be adequate to initiate the chimes. One thing to consider when rebushing a large hole is that any run out on the bushing machine will enlarge the hole. This is true of any bushing, but bigger bushings compound the error so the hole is too big for the bushing. If using a bushing machine, stop and check the size often. It will save you some grief ;)
     
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  7. R. Croswell

    R. Croswell Registered User

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    In many clocks the center wheel is part of the power train and under considerable loading. In such a clock, where only the minute arbor is through the bushing we need to treat this like any other going train bushing. If this is a clock like a typical American mantel clock where the hour pipe slips over the center arbor and we are talking about bushing for the hour pipe, then in most cases the there is little loading but it can be annoying if the hands are wobbly even if it doesn't affect the operation of the clock. I've had a few where the owner specifically requested that something be done, and I've bushed a few of my own just because it bothered me, but I probably wouldn't take a clock to a shop and pay someone to do just that. But if the clock is apart anyway, it isn't a lot of trouble if that's one's preference.

    RC
     
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  8. MARK A. BUTTERWORTH

    MARK A. BUTTERWORTH Registered User
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    In 3 train clocks the wear can be enough to not allow the lifting required of the unlocking lever required to unlock the chime train. For what reason this is particularly true in the Urgos UW32 series, but shows up in the other movements as well.
     
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  9. NEW65

    NEW65 Registered User

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    #9 NEW65, Aug 2, 2020
    Last edited: Aug 2, 2020
    Movement : Hermle 1151

    Thanks chaps for your replies.
    Jerry, the point you raised about the bushing machine is exactly why I submitted this post. I just pictured a situation of having to trim off a fraction of a millimetre using a bushing machine and the reamer being ‘pushed away!! I may be completely wrong as I don’t have a bushing machine! I know you cannot just turn the handle- the brass has to be (at least initially) nibbled. However regarding my query, I dare say most of us on here would not bother removing a fraction of a millimetre ie., Just finish up leaving the original hole with a very slight wobble in the pivot. I can see how the Mill wins over though when it comes to the above , Jerry!
    RC , thanks :) I totally agree with you, ALL replacement bushings have to be accurately relocated. However I have found that there is very little room for error when it comes to positioning the centre arbor bushing due to the effects on the minute and hour hand. There’s nothing worse than a sloppy minute or hour hand that doesn’t align with the numerals!
    R&A, I’ve ran into the situation that you outline on many occasions. Sometimes I’ve had to enlarge the hole further and fit a bushing in a bushing! I don’t like having to do that but sometimes I have had no option as I don’t carry a large variety of different size bushings. I think it’s okay though to do this if a snug fit is ensured.
    WOW, I used to hate the idea of rebushing the centre arbors! At one time I would have used a movement for spares to avoid this job! However there were two big problems associated with leaving sloppy centre arbors (1) quarter chime would not be reliable (always had to adjust the chime lift lever to compensate) and (2) the cannon pinion was pushed too tight against the minute wheel. And also too tight to drive a moon dial. I therefore decided to start rebushing the centre arbors.
    Mark & Shutt, yes absolutely essential on quarter chiming movements.
    Thanks everyone :)
     
  10. R&A

    R&A Registered User

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    Bushing inside a bushing is a pretty common practice on a lot of punched movements where the bushing won't hold unless you go bigger outside the punch marks. In some cases you can make a bushing and be done with it. I have bushed many center shafts plates. Other things have to be taken into consideration when installing. The height of the bushing on many occasions must be flush with the plates. If not flush you could have problems with end shake after installing the cannon pinion. Plus the cannon pinion must be low enough for the hour pipe to clear the minute hand when the minute hand nut is installed. << A mistake many repairman have not mastered. As a result the clock will not run and creates a power loss.
     
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