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S&S D

  • 1.  S&S D

    Registered Piano Technician
    Posted 10 days ago

    Hi, all.  I am about to restring the top octaves above the treble break of one of my university concert halls.  It was restrung a few years ago by someone else, and the top is full of false beats that you can't tune out ( at least I cant).  I am looking for a recommendation on a capo file from Stew Mac or someone(having never done a reshaping of a capo before).

      My thought is that it was pulled 100 cents high, so as to not have to tune it so many times, and in doing this, false beats were introduced throughout  the top 2 octaves.  I am not sure, but want to make this as good as I can by CA treating the bridge pins, reshaping the capo, and restringing.

       Thoughts??   Thank you.    

    Clark A Sprague, RPT



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    Clark A Sprague, RPT

    [csprague4@gmail.com]
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  • 2.  RE: S&S D

    Registered Piano Technician
    Posted 9 days ago

    Clark,

    I would recommend using a down bearing gauge to "map out" the forward and rear down bearing angles before you remove the strings. This will give you an indication of whether the problem is due to excessive or inadequate down bearing. Remove the bridge pins and sand down the cap in a manner that will correct any errors. Re-notch if necessary. If your rear is negative more than the front is positive you will need to sand down the aliquots. Ideally, you want a positive down bearing on both sides, although a negative in the rear is okay, up to a certain point. It's important that the speaking side is positive to at least 2 degrees. Also, you want to sand down enough material to "erase" the accumulated string groves – a primary cause of false beats. I would recommend replacing the bridge pins with new exact size pins and CA them into the bridge. Finally, be sure to reshape the capo bar – another source of false beats.

    Twenty-three years ago, I restrung a "D" at our community hall using this process and to this day the there are no false beats – including note #88.

    Roger Gable

    P.S. I noted you wanted to only restring the top 2 octaves. If you can't lift the plate to remove the bridge pins and sand down the cap, you may be up against an impossibility.



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    Roger Gable RPT
    Gable Piano
    Everett WA
    (425) 252-5000
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  • 3.  RE: S&S D

    Registered Piano Technician
    Posted 9 days ago

    Thank you, Roger.   I'm going to lower tension, but not remove the plate.  So, not sure how I'll approach but I hope to get rid of most if the false beats.  Thanks again!   Clark



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    Clark A Sprague, RPT

    [csprague4@gmail.com]Clark
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  • 4.  RE: S&S D

    Registered Piano Technician
    Posted 9 days ago
    I've restrung many a capo section, and always pulled bridge pins and surfaced the bridge (hand work). There will be a couple pins that you can't pull at each strut, but you can work around that. I insert new pins with CA, but I first coat the pins with McLube (444 if you still have it, otherwise 1725), putting them in a jar lid and applying a little liquid, then jostling them around so they all get coated. 

    It is VERY hard to remove a pin that has been CA'd in, and pretty much impossible if they've been epoxied in. If the pins can't be removed, recapping becomes impossible. I like to think of my successors, and try to work so they won't be cursing me :-)

    I generally surface the capo by hand with sandpaper, making a Vee between my finger and thumb and bearing mostly on the sides of the bearing point. Go through the grits. Examine regularly using a flashlight and mirror. 

    I don't believe capo issues cause false beats, but they do cause frictional issues and sometimes noises. Dress the upper bearings as well, and either replace the under felt or at least lubricate it (I brush with McLube).
     
    Regards,
    http://fredsturm.net
    www.artoftuning.com
    "Education is not preparation for life; education is life itself." John Dewey






  • 5.  RE: S&S D

    Registered Piano Technician
    Posted 9 days ago

    Thanks, Fred.  



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    Clark A Sprague, RPT

    [csprague4@gmail.com]Clark
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  • 6.  RE: S&S D

    Registered Piano Technician
    Posted 7 days ago