Pianotech

  • 1.  dampp-chaser liquid treatment for balance key hole ?

    Posted 05-19-2023 11:18

    Hello everyone, 

    I'm used to use the glue-sizing method (cardinal points needling inside the hole and water-wood-glue mix 70/30) but it doesn't work everytime (wood swells then retracts overnight). So I was searching for an alternative to the more invasive fixes. I read somewhere recently the dampp-chaser liquid treatment can be used to swell the wood around the balance key hole and I've just tried it. I would say it seems to work but is it better than to glue-size the wood ? Maybe...  As a matter of fact, It seems that the dampp-chaser liquid applied at the room temperature (a thin paint brush of the liquid inside the bal. rail hole) makes the wood swell enough to a better pin fit and the correct friction is preserved (the key falls in a smooth but easy way during test). Perhaps the liquid pad treatment can be more efficient at hot temperatures. I just got to make tests about it. 

    What's your best way to fix a moderate reamed key hole ? I often see pianos with no ''pulley'' key here but when I do the test (lift up the key back 1 – 2mm and release) often I have many keys that fall too easily with no friction at all and I can hear (but not see) a very tiny knock when I push-pull some keys. 

    Thank you,



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    Bruce SATO
    QC
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  • 2.  RE: dampp-chaser liquid treatment for balance key hole ?

    Registered Piano Technician
    Posted 05-19-2023 12:12

    I don't have an answer to your question, but once I tried using Chair Doctor.  It swells the wood so that the joints in the chair tighten up.  I thought it would work well for balance rail holes.  It did work, but it made the keys click really badly in the balance hole, and nothing I tried would make the click go away.  Be careful what you use.  I've tried using a voicing needle to make holes around the balance rail hole, along with glue sizing, with limited success.  You can also rub the surface of the hole with a dull rounded tool to close up the hole, again your mileage may vary as to how long it might last.



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    Paul McCloud, RPT
    Accutone Piano Service
    www.AccutonePianoService.com
    pavadasa@gmail.com
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  • 3.  RE: dampp-chaser liquid treatment for balance key hole ?

    Registered Piano Technician
    Posted 05-20-2023 06:05
    I've had very good luck glue sizing over the years, including some that I would have thought lost causes, with noticeable side-to-side play as well as back and forth. 

    Using a balance hole sized brush, I start by painting with boiling water to swell the holes then immediately follow up with very thin glue while the wood is still warm. I've used both titebond and hide glue with the same results. After drying a day or two I fit the keys individually with the tapered burnishing tool leaving them just a tad tight. Lastly I paint the inside of the holes with McLube and lightly burnish in a little teflon powder. This, plus more McLube on the pins gets me the fit I want while still leaving the hole as snug as possible. All this represents a fair amount of labor, so I usually do it as part of key bushing (and sometimes key pin) replacement jobs. 





  • 4.  RE: dampp-chaser liquid treatment for balance key hole ?

    Registered Piano Technician
    Posted 05-20-2023 10:21

    Thanks for sharing your protocol, Mark. Sounds promising. Think I'll try it out on the set of keys currently in the shop for rebushing.

    Alan 



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    Alan Eder, RPT
    Herb Alpert School of Music
    California Institute of the Arts
    Valencia, CA
    661.904.6483
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