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String rendering from tuning pin to front termination question

  • 1.  String rendering from tuning pin to front termination question

    Registered Piano Technician
    Posted 06-20-2017 02:09
    While I experience this problem on a number of pianos, I have one piano that I service frequently that is, unfortunately, the hardest piano I have to tune. And even though I know I'm brought in so frequently because of uncontrollable AC in a large room, (don't ask), I nevertheless know that the tuning that I'm struggling to leave on this piano is not going to stay very long. 

    Kawai   GS-70   from 1988   in generally very good condition. 

    No problems in the bass or middle, which are all agraffes, but the notes from the treble break up to the top just will not allow me to set the string and have it stay where I put it. It's one of those issues where you turn the tuning pin and the pitch does not change. The string is friction bound across that wide spread of felt, then over the brass half round where it makes a steep curve through the front duplex and finally across the capo. I have cleaned these surfaces and I have used Protek CLP on all the bearing points. This has noticeably helped, but not nearly enough. Pounding harder than I normally ever do on a well behaved piano also helps a bit, but it also tends to knock out the tuning of the other strings in that unison that I thought I had already set. Even when I think I may have everything set I discover that the strings are not at all stable. 

    I'm afraid to lubricate too much because I know that some friction in this area is absolutely necessary. 

    Looking for help, tips, tricks, whatever you have up your sleeve. Things that cost more than a little money may be nice to know, although time is OK, but there's no money to put into this piano as long as I'm available to tune it frequently. And normally I wouldn't mind this, but the struggle just wears me out. I service many pianos for this customer and we have a really good relationship, but I hate this piano. And I don't want to.

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    Geoff Sykes, RPT
    Los Angeles CA
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  • 2.  RE: String rendering from tuning pin to front termination question

    Registered Piano Technician
    Posted 06-20-2017 04:06
    Geoff

    The only suggestion I can make is that there could be burrs on the strings. Little notches that keep the string from rendering over one of the bearing points, until you put too much tension on the strings, and then it jumps. 

    The solution is to release the tension of one string, and pull it up on the other. This gets the burr or notch away from the bearing point.

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    Willem "Wim" Blees, RPT
    Mililani, HI 96789
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  • 3.  RE: String rendering from tuning pin to front termination question

    Posted 06-20-2017 07:58
    If the underfelt is too compacted and adding friction, can it be under cut with a MultiTool blade to relieve some pressure? I had an Asian piano with that problem and I was considering an angled plunge from each side under the unisons to hopefully remove material. Fortunately his new piano teacher recommended her tuner and it's no longer my nemesis.

    If the string angle coming up from the v-bar to the counter bearing is too steep, the only way to tune that is to pull into tune and leave it. There is no finessing the pin when there is that much resistance. The same goes for many Aeolian products:  M&H, Chickering to name a few.

    If there weren't such a severe rendering problem I'd suggest tightening the coils with a pair of parallel pliers.

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    Regards,

    Jon Page
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  • 4.  RE: String rendering from tuning pin to front termination question

    Posted 08-15-2017 22:29
    Jon,

    I had tried this undercutting on a Hallet&davisfinegermancraftsmanshipmadeinchina awful excretion of a PSO, which I now refuse to tune...or rather make refused to try to tune. Ended up at the Chiropractor every time and it still was out of tune in a half-hour. The combination of termination angle (both agraffe and capo sections), wide brass bearing counter-bearing, followed by dense felt stuffed well under the strings makes it utterly un-readable. Strings move up, but never down.

    I tried, as a test, before condemning the damn thing, taking a razor and cutting a "V" under the compressed felt behind the brass counter-bearing... All the way to no felt/string contact at all. To my surprise there was no difference at all that I could discern. I expected some change...but nada...pitch moves up, but not down. 

    I think its a whole bunch of things conspiring to create this mess...too wide a counter-bearing surface, too steep a termination angle, the compressed felt, 15 yr old string corrosion, and I bet inappropriate metal used in the strings. One possibility, I think that could also apply to apply to Geoff's Kawai, which at 80's vintage might be a similar materials issue, is that the wire itself is at fault, because the string does not move in both the different termination conditions presented by agraffes and capos. I'm not sure of what metallurgical problems are present, but one guess might be wire is made from recycled metal. Recycled, with uncertain admixtures of elements, and, in that time in China's rise, untrustworthy sourcing ie corrupt suppliers giving false material composition certifications.

    Horrible horrible piano, and I have tuned other Hallet&davisfinegermancraftsmanshipmadeinchina PSO's with the same MO  
     


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    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
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  • 5.  RE: String rendering from tuning pin to front termination question

    Registered Piano Technician
    Posted 06-20-2017 09:51
    Geoff,

    You might try letting the tension down on each string so you can just pull the string off the underfelt (between tuning pin and bearing bar). Deflect the string just enough that you can mark in the string groove with a sharpened #2 wood pencil.  The graphite in the pencil lead gives some lubrication to the interface between string and underfelt.

    My technique was to lower the tension a musical 5th in (e.g.) the L string of a shared unison first, then lower the shared C string and mark with the pencil, then bring the C string back up to match pitch of L string, then lower L string to mark with lead, then bring both strings back to match the pitch of the R string.  I found that dropping tension as described above gave good stability when the strings were brought back to pitch.

    The procedure cured an almost impossible "click-slip" rendering in the tenor agraffe section of my S&S M.  I also discovered that (on my instrument) a single light mark in the groove with the pencil produced good results.  Multiple marks in the same groove made the string rendering a bit too easy.

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    John Rhodes
    Vancouver WA
    360-721-0728
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  • 6.  RE: String rendering from tuning pin to front termination question

    Registered Piano Technician
    Posted 06-20-2017 10:18
    I suspect the V-bar on this piano is hardened. Hardened V-bars do not render the string movement as readily as normal soft, gray iron plates. I have a Kawai from the same era with the same tuning problem and the V-bar is hard. When gray iron is hardened, some of the graphite form of the carbon in the metal is converted into a diamond-like form. This is abrasive.

    I also have several Steinway and Yamaha pianos with the same problem.

    The industry needs standards for the plate termination points of the string. Hard, round V-bars and curving slope agraffe string holes are all wrong!! So are hard bridge pins!!!

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    Edward McMorrow
    Edmonds WA
    425-299-3431
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  • 7.  RE: String rendering from tuning pin to front termination question

    Registered Piano Technician
    Posted 06-24-2017 10:06
    Just had this situation yesterday on a Story & Clark grand. VERY frustrating! Living helped a little...but still a pain in the beck.

    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
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  • 8.  RE: String rendering from tuning pin to front termination question

    Registered Piano Technician
    Posted 08-15-2017 20:27
    Edward --

    So do you think that once the V bar has become hardened all I can do is just live with it? In combination with Wim's suggestion to shift the position of the string, which I intend on trying on next visit, (I was just there today and the piano reminded that I still need to deal with this),  do you think that if I were to file or sand down the grooves in the V bar until it was smooth again that might help, too?

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    Geoff Sykes, RPT
    Los Angeles CA
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  • 9.  RE: String rendering from tuning pin to front termination question

    Posted 08-15-2017 22:32
    <curving slope agraffe string holes 

    Hi Ed...what do you mean by this curving slope agraffe string holes??

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    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
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  • 10.  RE: String rendering from tuning pin to front termination question

    Posted 08-16-2017 07:54
    As with some Aeolian products that have a high counter bearing angle, you just pull to pitch and leave it. There is no finessing of the pin torsion. Set it and Forget it (I heard that somewhere).

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    Regards,

    Jon Page
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  • 11.  RE: String rendering from tuning pin to front termination question

    Posted 08-16-2017 12:28
    You mentioned that you had lubricated the bearing points with CLP.  Do you understand the understring felt to be a bearing point in this scenario?  Have you "drawn a line" of CLP on the felt immediately adjacent to the string?  I have found this to be very helpful on some pianos.

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    Floyd Gadd
    Regina SK
    306-502-9103
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  • 12.  RE: String rendering from tuning pin to front termination question

    Registered Piano Technician
    Posted 08-16-2017 12:44
    Floyd --

    Yes, I consider the understring felt a bearing point, and I did run a line of CLP on the felt along each string. It actually helped quite a bit. I don't want to over lubricate the felt, however, because a little bit of friction there is actually very helpful. It helps equalize some of the tuning pin twisting that would otherwise make setting the pin almost impossible if it weren't dampened a bit.

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    Geoff Sykes, RPT
    Los Angeles CA
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