CAUT

  • 1.  Repairing knuckles vs replacing

    Posted 01-15-2017 07:47
    Hello everyone!

    I am no expert in piano engineering and tuning, I am a beginner, a hobby enthusiast, and I love to learn and try new and odd stuff :)

    I am restoring a grand action and budget is an issue... Also, in Romania you cannot find piano supply stores, and most of the ones in Europe won't sell parts to non-professional piano technicians... I am barely starting this career now...

    The knuckles are pretty bad worn (flattened with pretty visible jack indents). The leather seems to be in an acceptable shape... I cannot afford a knuckle replacement set, so I searched the net for various methods of repairing...

    What I have come up, rather than bolstering with yarn is a simple method to restore the compressed fibers of the felt inside the leather.

    I drilled a 10mm (diameter) hole in a piece of wood, then cut it in half to make a caul, or mold (i don't know exactly the english word..). I then heavily impregnated the knuckle with isopropyl alcohol (as it came from the store, not further diluted with water) and applied the caul with a clamp. After about 2 hours, when I removed the clamp, the knuckle was perfectly round with no jack marks and holding shape (it seemed to have the same stiffness everywhere).

    I still have a lot of knuckles to reshape, so I haven't had the chance to test them yet... but I'll let you know. It seemed like an interesting experiment. And it might work, because, I think, the felt should be intact inside a worn knuckle, only compressed in a wrong way... don't you think?

    I would be so curious what a professional would have to say about this experiment... :)

    Cheers!!!!

    Ovi

    ------------------------------
    Ovidiu Turcu
    Piano Tuner and Technician
    Bucharest
    +40724414692
    ------------------------------


  • 2.  RE: Repairing knuckles vs replacing

    Registered Piano Technician
    Posted 01-15-2017 11:55

    Two things:
    1) I would worry about the water content of the isopropyl alcohol (probably 30%) affecting the leather, making it hard. Hard leather can be more of a problem than wear, as it leads to a lot of action noise.
    2) I have found that steaming wippen cushions to remove the dent from wear and compression is pretty temporary in effect, that it only lasts a few months (in a high use practice room situation). So I would expect that this would also be pretty temporary - but that is speculation, and I'd be interested to see what results you observed.




    ------------------------------
    Fred Sturm
    University of New Mexico
    fssturm@unm.edu
    http://fredsturm.net
    http://www.artoftuning.com
    "We either make ourselves happy or miserable. The amount of work is the same." - Carlos Casteneda
    ------------------------------



  • 3.  RE: Repairing knuckles vs replacing

    Posted 01-15-2017 15:55

    Hi!

    Thanks for the answer! You have a point with the leather!!!.. I knew (and forgot) that leather is sensitive to water..

    However, after reading your reply, I went to the action to check and, to my touch, the leather on the reshaped knuckles seems to feel the same softness. You can still feel the nap. The fingers won't feel the treated knuckle different from the untreated one..

    Strange, but it does not say the percent of water on the label, it says just "High purity isopropyl alcohol IPA"..

    Hope that teflon powder (never used it yet) will prevent noises.....

    I'll let you know what are the results, in a few days :)

    Best to you!

    Ovi




    ------------------------------
    Ovidiu Turcu
    Bucharest
    +40724414692
    ------------------------------



  • 4.  RE: Repairing knuckles vs replacing

    Posted 01-18-2017 05:07
    Here are 2 pictures:


    ------------------------------
    Ovidiu Turcu
    Bucharest
    +40724414692
    ------------------------------