Joe, That piano was a Chinese Hallet stencil grand (Dongbei) on the video. That piano was one of the ones I re-worked the front segment on. That one was a partial success, as I was just getting my protocol down. Its way easier and predictable to tune now, but counter bearing friction was too low in the capos. I've figured that out better since then.
Its a confluence of forces that make a front segment impossible to read. You have to read all the parameters on that piano..and they are all different model to model. The diagnostic combines:
-termination angle
-material of counterbearing...brass, cast iron, stainless (real pain), felt,
-radius width of capo, as opposed to an actual "V" shape
-resolution of counterbearing angle to the pin...is it a second acute angle, or a minimal angle off counterbearing to the pin
-length of front segment(s)
-corrosion conditiions
-how many miles of felt
-angle of the slope
-how deeply has the string worn into the counterbearing. because of acute angles
-is there a double counterbearing (usually the worst setup for impossible to read front segments, as it adds a third segment to the front segment)
-is there a metal counterbearing followed by stiff,understring felt...if so, how thick is the felt
There are more probably. One reads all these conditions, which will be different on every piano model, and different in each section of each piano. One looks at the combination of front segment conditions and adjusts termination angles (grinding the plate), counterbearing ,materials (co-polymer on high termination angle problems), reduces capo and counterbearing contact areas, by making true V's not wide 1/4" or more radii, introduces friction when angles are too low, etc, etc. Its a chess game, on each piano and each section. Also keeping the pin torque controlled is a real help. High pin torque and a few challenging counterbearing conditions, make the front segment residual tensions real tough to read.
The interesting thing is, that even if you absolutely never rebuild, and are exclusively a tuner, reading these physical attributes of the front segment, can seriously improve stability in a big way. It did for me. It makes it so you always know what you are up against, on every pin, and are never surprised. Since I worked this all out in my mind, plus the excellent discussion Fred Strum and David Love had a couple of years ago, about how the lever can be used to influence front segment forces, makes reading the forces in the front segment, including tuner forces, a clear and rational exercise.
I want to put this all in an article..but I am so busy with other really cool experiments in the shop, I haven't had the time to sit down and write it..
------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
------------------------------
Original Message:
Sent: 12-04-2021 14:59
From: Joe Wiencek
Subject: Unison smear?
Jim,
I wasn't aware that piano tuner was on Jesus' resume, haha!
Do you have any pics you'd care to share of your reworking the front segment? I'd be willing to bet that one of them you did was on my favorite (sic) capo section front segments, the Kawai grand. (The video Floyd Gadd posted of your action trolley bench showed you single handedly reaching into the cavity to retrieve the action. I've only witnessed that possibility on Kawais.)
Very curious how you solved reading the front tension!
Joe Wiencek
NYC
Original Message:
Sent: 12/2/2021 3:01:00 PM
From: Jim Ialeggio
Subject: RE: Unison smear?
Steve, The energy you speak of is contained, or as is often the case, inadequately contained in the front segment of wire...the entire length of wire between capo and tuning pin. Some front segments are so badly designed, Jesus Christ himself would not be able to tune them with stability. This calls for a redesign the bloody front segment , and reshape the capo to make the front segment. This makes it easier to read and install a known residual tension. I've done this on numerous Asian pianos, that were absolutely impossible to tune with stability.
------------------------------
Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
Original Message:
Sent: 12-02-2021 14:46
From: Steven Rosenthal
Subject: Unison smear?
I used to tune a small Boston grand that was in a jazz club. It was fairly old, probably one of the original Boston models. The piano stayed in tune quite well except for the 5th and 6th octaves; not only did it consistently drop 5-10 cents but over the years about a quarter of the strings in that area broke. I don't think the temperature/rh fluctuations were too great and, being in the tropics, were always above 70º/50% and up to mid 80's for both temp and rh.
I tuned it once a month, pre-tuning the 5th & 6th octaves first, and the treble would go out in the first set it was played. It needed action work that the owner couldn't afford that probably contributed, at least he tried to keep it in tune.
I've always wondered, where does that energy (tension) go? One might think that sooner or later they system would stabilize but it doesn't. Perhaps the cabinet posts have unseen glue failures and the posts are "squirming"? The pinblock is moving? If the problem involves the bridge pins, wouldn't the damage accumulate over time to the point where it was visibly obvious? The bridge pins on the Boston appeared fine.
------------------------------
Steven Rosenthal
Honolulu HI
808-521-7129
Original Message:
Sent: 12-02-2021 13:43
From: Scott Kerns
Subject: Unison smear?
"Bottom line: I tell my customers that if they want tuning stability, they need to control RH in the room. Period." - Fred Sturm
I totally agree with that. Also, with churches and institutions that can't, don't or won't control temp. & RH in the room, they just need to schedule regular tunings. I've gained some ground in this area and have convinced some to do that. It's made a lot of difference.
------------------------------
"That Tuning Guy"
Scott Kerns
Lincoln, Nebraska
www.thattuningguy.com
PianoMeter, TuneLab, OnlyPure, PianoScope & PiaTune user
Original Message:
Sent: 12-02-2021 11:35
From: Fred Sturm
Subject: Unison smear?
I was involved in beta testing a humidity control system that sealed the bottom of the piano (plastic taped to the rim, foam around the nose bolts) and maintained the RH within + or - 1% (data logger in the cavity showed that this was true). This was on a Kawai RX-2, perhaps the most sensitive to RH variation in creating unison smear where right and left strings consistently move in the same manner, and with especially large differences in octaves 5 and 6.
I found, to my surprise, that the result of this installation was minimal, if it made any difference at all. I theorized that it must be exposure of the top of the soundboard and the bridge. I installed a string cover like Dampp-Chaser's undercover, and measured RH under it and in the room. Zero difference. I installed a thick wool string cover, doing my best to seal the edges. Zero difference. Tuning just as unstable, RH the same inside and outside.
I have puzzled for decades about the unison smear in response to RH swings. I have concluded it has to the the bridge. Exactly what mechanism, I don't know. It may have something to do with bridge notching, how far the pin is from the center of the the bridge affecting how far it moves either fore/aft or laterally or both. One factor that leads me to this conclusion is that both grands and uprights exhibit this behavior, and both have the same bridge setup relative to this factor, though in other senses they are opposite (relative lengths of string between bearing and tuning pin, for instance).
I am relatively convinced that the soundboard has little or nothing to do with it.
Bottom line: I tell my customers that if they want tuning stability, they need to control RH in the room. Period.
------------------------------
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
Original Message:
Sent: 11-29-2021 17:47
From: Ron Koval
Subject: Unison smear?
Knabe grand a few decades old - so built in Asia. Serial number starts with YG...
While I've observed unison smear in other pianos, (as humidity shifts individual strings of the unisons move by different amounts - sometimes even one going sharp and another flat...) this one is the most drastic example of that phenomenon.
The owner is going to try room humidity control first, but this one will most likely require a full Dampp-Chaser with bottom and top covers to help...
But here's my question: I'm having a hard time coming up with a hypothesis for what could cause it - any ideas? The best I've been able to imagine is if the pinblock is expanding and contracting; that way the pins farthest away would possibly push and pull more???
Today was 32%, a few weeks ago was 45% The amount of smear was 10 cents or more around the middle of the piano... Crazy!
Ron Koval
------------------------------
Ron Koval
Chicagoland
rontuner@hotmail.com
------------------------------