On 3/7/2014 9:21 AM, Ed Sutton via Piano Technicians Guild wrote:
Sorry, send is directly below edit and I miscued.
> I don't see any "balance of string tension" in a piano.
Across the scale, bass and treble. The same reason so many worries have
been posted about removing the bass strings to replace or repair a bass
bridge. Puts the tension out of balance across the scale.
> To me it looks like they are all pulling against the case and plate,
> not against each other.
Against the plate, yes. Against the case, not much. That's what plates
are for.
> Thus, I believe
> this is one of those stories that gets passed on, generation to
> generation, any the threat of imagined bad consequences enforces the
> behavior.
Yes. If you cross your eyes, they'll stick like that.
> I would be grateful if someone can give me a reasonable
> explanation for the need to release tension little by little when
> restringing. Has anyone had firsthand experience of a plate breaking
> or case or soundboard damage cased by releasing string tension?
> (Firsthand, please, not a passed down story.)
My call is this: I can't see the stress in the plate, so I can't say in
any given instance how much leeway I have. In most cases, it's
considerable, but in the case of a broken plate, the price is awfully
high for throwing caution to the winds and guessing wrong. Every time I
chip a restring to pitch, I'm not entirely comfortable until it's up and
had a couple of tuning passes. I hope never to hear "The Sound".
In the case of removing the bass strings, I've never lowered overall
tension doing that and don't intend to. Restrings are regularly pulled
to pitch to settle the bends install braid before the bass strings are
even installed, and I haven't heard from anyone that it has been a problem.
In destringing, I lower the center string all the way across, then left,
right, etc. It costs me nothing extra in time, and thus isn't
pathologically cautious. When I can get added safety or quality in
result in anything at no extra cost in time, I'll do it. There's no
point in being terrified of a plate under string tension, but there's
also no point in ignoring real if unlikely potential for disaster.
The soundboard? It's probably already shot, but even if it's not, taking
minimal precaution with the plate covers the board too. You almost
certainly can't (further) hurt the soundboard whatever you do, but the
plate is worth some minimal caution, like installing the perimeter lags
and the plate horn wedge before chipping to pitch.
Ron N
Original Message------
Elsewhere I am reading a discussion of the need for careful, gradual release of tension across the piano while destringing.
The concern is that somehow, if the tension is released too suddenly from one section of the piano, the piano will become "unbalanced" and it may cause the plate or case to break or twist, or it may injure the soundboard.
I don't see any "balance of string tension" in a piano. To me it looks like they are all pulling against the case and plate, not against each other. I don't see any problem with removing the strings any way that works, and I have not had any pianos collapse from the stress of having string tension removed.
Thus, I believe this is one of those stories that gets passed on, generation to generation, any the threat of imagined bad consequences enforces the behavior.
I would be grateful if someone can give me a reasonable explanation for the need to release tension little by little when restringing.
Has anyone had firsthand experience of a plate breaking or case or soundboard damage cased by releasing string tension?
(Firsthand, please, not a passed down story.)
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Ed Sutton
Editor
Piano Technicians Journal
ed440@me.com
704-536-7926
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