Yamaha GB1 tuning stablity problems.

[pianomanpat]

Hi folks.  I have a Church that has a fairly new yamaha GB1 which has been a thorn in our sides because in spite of a Dampp-Chaser system and a undercover it still is very unstable in its tuning.  The fit of the plate flange to the pinblock sucks, with a gap of more than .025ths in places.  I have been told of filling the gap with epoxy.  Can anyone make any suggestions as to the best type of epoxy and what type of clay to use to make a dam with to protect the piano?  Pat Buongiorne

[David Renaud]

Hello

Another approach is to make some custom V shaped shims out of hard rock maple, coat them with a bit of epoxy and tap them up between the flange and pinblock so as to eliminate any of 2 inches or more. lay something impenetrable on the keybed while it sets in case. Mix West system with enough filler so it is pasty enough to add fill around,and in addition to the shim , and not all dip out.

Dave Renaud

Sent from my iPad

[tnr...@aol.com]

I have a Church that has a fairly new yamaha GB1

Yamaha's are not supposed to have a gap like that. How old is the piano?  Have you contacted the store that sold the piano? This might be a warrantee issue.

 

Wim

[tnr...@aol.com]

I have a Church that has a fairly new yamaha GB1

Yamaha's are not supposed to have a gap like that. How old is the piano?  Have you contacted the store that sold the piano? This might be a warrantee issue.

 

Wim

-----Original Message-----
From: pianomanpat <piano...@gmail.com>
To: pianotech <pian...@googlegroups.com>
Sent: Sun, May 5, 2013 11:24 am
Subject: [ptech] Yamaha GB1 tuning stablity problems.

[Ron Nossaman]

On 5/5/2013 4:24 PM, pianomanpat wrote:
> Hi folks. I have a Church that has a fairly new yamaha GB1 which has
> been a thorn in our sides because in spite of a Dampp-Chaser system and
> a undercover it still is very unstable in its tuning. The fit of the
> plate flange to the pinblock sucks, with a gap of more than .025ths in
> places.


> I have been told of filling the gap with epoxy.

So have I, and the Easter bunny too. I've just never found it to be an
effective fix. Before the random suggestions pour in by the dozen, let's
define the problem. Where and how does the piano go out of tune? Unisons
only? Bass? low tenor? Mid tenor? First capo section? Treble, or all
over? Sharp? Flat? What? Do they turn the heat on when you arrive, or is
it left alone when you're scheduled to tune? Let's find out what we're
talking about before we start talking.
Ron N

[Isaac OLEG]

Le dimanche 5 mai 2013 23:24:31 UTC+2, pianomanpat a écrit :

Hi folks.  I have a Church that has a fairly new yamaha GB1 which has been a thorn in our sides because in spite of a Dampp-Chaser system and a undercover it still is very unstable in its tuning.  The fit of the plate flange to the pinblock sucks, with a gap of more than .025ths in places.  I have been told of filling the gap with epoxy.  Can anyone make any suggestions as to the best type of epoxy and what type of clay to use to make a dam with to protect the piano?  Pat Buongiorne

I wonder if the slight gap at the bottom of the pinblock is showing anything, eventually it show a block that is slightly rotating , but the string's tension does not apply there, in my mind , all is concentrated at the lip. If any motion it goes in direction of making that space larger, if filling it solve instability problem I trust you but I have some doubts.

[pianomanpat]

The piano is just over 5 years old.  Have contacted Yamaha only to get a run around and denials that there is a manufacture cause!  And yes you're right, the gap shouldn't be there!

[pianomanpat]

Usually the unisons in the 5th and 6th octaves are the first to go.  The gap goes clear to the plate and doesn't seem to be tapered too much.  It looks like it was just cut and screwed on with little or no fitting!  I have discussed the shim idea but it seems like it would be difficult to get wooden shims thin enough in there that would fill the gap to the plate without them failing. 

[John Krucke]

Hi Pat, 

 Have you seated the strings at the hitchpin and bridge?

John Krucke

[Isaac OLEG]

Did you probe the gap with a thin metal blade and measure the deepness and thickness ?I doubt there is any gap at the lip location. If there is this is a guarantee question, and I would send exact description of the trouble, pics, measurements, and have the piano replaced. Did you check the plate screws in the pinblock ? 

[MARK WISNER]

To my knowledge, Yamaha has never fit the pinblock to the plate flange, relying instead on hardwood tuning pin bushings and 

plate web screws to hold the pinblock immobile to the plate.  If you check a Yamaha grand that holds a tuning well you'll find that it will have pinblock to plate gap, which in my mind makes an assumption that the gap is responsible for the instability a little suspect.

If all other possibilities are eliminated you might consider leaving a USB data-logger on the piano for a few months to record the temperature and RH at 20 minute intervals.   The results are usually surprising. 

Mark Wisner

 

---

From: Isaac OLEG <isaac...@gmail.com>
To: pian...@googlegroups.com
Sent: Tuesday, May 7, 2013 11:13 AM
Subject: Re: [ptech] Yamaha GB1 tuning stablity problems.

[Isaac OLEG]

Greetings,

I do not understand your answer. There must be at last a sort of match between plate lip and pinblock edge. at worst with some sort of joint added if  no fitting is done.

I have heard that the pinblock was reinforced with metal sheet , also, but counting only on screws for such a tension does not make sense to me. Even a fit done with an automat is possible, due to the high precision of the molded plate.

I have not precise memory of the pinblock aspect but the plate have a lip for sure. 

Regards

[Will Truitt]

On more than one occasion, I have found unusually unstable grand pianos where there were large gaps between the plate flange and the face of the pinblock that had plate bushings.  Some of these were even unstable during the tuning (as I tune one end, the other is drifting out, and go back and forth ad finitum).  It has always been my experience that these instruments stabilized after making up tapered maple shims, putting glue on one side, and driving them into the gap as far as they would go.  Then I would trim the excess off the bottom. 

 

Other instruments would tune reasonably but that tuning would be short lived.  The introduction of maple shims stabilized these pianos when tightening plate screws did not.  The instability of a dry Northern climate and the vagaries of tenor scaling on these G 1 series pianos does create instabilitiy in these pianos as well as most others, yes.  But I don’t think climate is the whole story, Mark.  In my direct experience on multiple occasions, mating the pinblock to the plate flange by inserting maple shims generated a noticeable improvement in stability.  Since I am the tuner following up on these changes over a period of time, I am satisfied as to the utility of doing this.

 

Also, I have seen many Yamahas (and many other brands) that had plate bushings and poorly fit pinblocks.  It is not uncommon to see gaps in the plate bushing develop at the back of the tuning pin, with the front of the pin crowding the bushings.  You see it most particularly in the bass.  That would suggest that the pinblock is moving and yielding to the pressure of the strings, and that the plate screws are not enough to restrain this movement, nor are the plate bushings. 

 

Will Truitt

[Isaac OLEG]

those are the cheap series made in Indonesia, then. 

[Joseph Garrett]

No they are not.

 

Joe Garrett, R.P.T.

Captain of the Tool Police

Squares R I

http://gpianoworks.com/

 

[Ron Nossaman]

On 5/6/2013 4:03 PM, pianomanpat wrote:

> Usually the unisons in the 5th and 6th octaves are the first to go.

On a dozen or so occasions through the years, I've been called to tune a
Yamaha that wouldn't stay in tune.A couple no more than a week after the
previous tuning. I'd find that from somewhere around the beginning of
the capo section up, unisons were awful, where from there down, the
tuning was fine. During the tuning, I'd whack the key one good test blow
as I tuned the first note of each unison, and in the first capo section,
the pitch would drop considerably. I guarantee I didn't move the
pinblock with my test blow. Tuning the unison, I noted that the other
strings had dropped too. Next unison up, same thing. What's happening is
that the string is rendering through the bridge. It won't do it
immediately with just tuning, but a good test blow will usually help it
along. Once it's moved, the tuning will stay put in the usual manner. If
you don't, there's a good chance the tuning won't last long. Sometimes
they don't do this, and can be tuned with no special accommodation, just
like you normally would.

Why this is so Yamaha specific, I don't know for sure, but I find it a
lot and this has become a standard procedure when tuning them. When or
if I got to talk to the previous tuner, they said they didn't do this.

So whatever your test blow procedure is during tuning, give each note
(or string) one good whack, and recheck. With the Dampp-Chaser system
already installed, this should do it.

As Mark said, Yamaha doesn't fit blocks to plate flanges. So says
Yamaha, and none of those I've ever checked have been fitted. Yet with
the exception of the bridge rendering thing which can be accommodated
during tuning, I find them to be as stable as any production piano.
Ron N

[pianomanpat]

Been there, done that.  there are other yamaha pianos in the same town that don't move neither as much as this one does!  The results did show that there is of course RH swings but not enough to be the cause with the DC system and the undercover.  

[pianomanpat]

I use a Reyburn tuning pounder to set my strings with.  It does a very, almost too good, job.  You have to be careful with it to not over do it!  Believe me, the strings get set.  And as I said there are other Yamaha pianos in this town that tune up fine and hold their pitch fine with clean unisons.   

[MARK WISNER]

Check the pinblock/plate flange fit on some that stay in tune and unless a tech has modified it, it'll have a gap.  Also, this construction was used in both Japanese and Indonesian factories on everything from C7s to GH1BS.

One thing I think is curious, though;  If the string tension is pulling the tuning  pin towards the speaking length side, wouldn't the plate & bushing act as a fulcrum on the pin causing the lower part of the pin be to push the pinblock away from the plate flange, making the fit of the two even less consequential?   

Mark Wisner

---

From: pianomanpat <piano...@gmail.com>
To: pian...@googlegroups.com
Sent: Tuesday, May 7, 2013 5:58 PM

Subject: Re: [ptech] Yamaha GB1 tuning stablity problems.

[Ron Nossaman]

On 5/7/2013 5:19 PM, MARK WISNER wrote:
> GH1BS.
>
> One thing I think is curious, though; If the string tension is pulling
> the tuning pin towards the speaking length side, wouldn't the plate &
> bushing act as a fulcrum on the pin causing the lower part of the pin be
> to push the pinblock away from the plate flange, making the fit of the
> two even less consequential?

The higher density cap on the block would make that much less likely.
How about all those Steinways out there with low density blocks and all
the pins riding directly on the plate? If the string tension is
supported by the hard bushings, or plate webbing directly, flange fit
should be unnecessary. With no bushings, and the pins not riding the
plate, the block to flange fit is what supports string tension. So, as
usual, one "rule" doesn't fit all constructions.
Ron N

[Joe DeFazio]

MARK WISNER wrote:

To my knowledge, Yamaha has never fit the pinblock to the plate flange, relying instead on hardwood tuning pin bushings and 

plate web screws to hold the pinblock immobile to the plate.

Will Truitt wrote:

On more than one occasion, I have found unusually unstable grand pianos where there were large gaps between the plate flange and the face of the pinblock that had plate bushings.  Some of these were even unstable during the tuning (as I tune one end, the other is drifting out, and go back and forth ad finitum).

I learned about Yamaha's flange/block  (non-) fitting here on this list some time ago.  Is it a factor in this particular piano's instability or not?  We don't have enough information to say at this time. 

Since all things are not equal, I think that the key thing here is to analyze the pattern of the out-of-tuneness. 

If the treble and bass seesaw  back and forth as you tune, with the bass pulling sharp as you tune the treble (and vice-versa), then the "epoxy slathered hardwood wedge shims" may well improve things. 

If the out-of-tuneness does not follow this pattern, then the epoxy wedge treatment is not likely to help. 

pianomanpat wrote:

The piano is just over 5 years old.  Have contacted Yamaha only to get a run around and denials that there is a manufacture cause! 

Hi Pat,

I would be very cautious about "blaming" Yamaha for a manufacturing problem. Yamaha's manufacturing standards are very high, and as others have said, lots of Yamaha pianos with intentionally unfit block/flange areas stay in tune very well.  

There well may be another cause for the instability, and Yamaha is about the last company that I would expect to get "a run around and denials" from.  Of course, if one blames them for something that is outside of the design and manufacturing process that they have chosen and had great success with (and thus should not be responsible for), then I would expect them to (rightly) reject that inaccurate portrayal of the situation. That would be analogous to "blaming" Steinway for choosing aliquot plates instead of individual aliquot bars (like, say, Baldwin).  Both approaches are valid, as the tens of thousands of professional pianists attest by choosing fine pianos by those manufacturers). So is Yamaha's block fitting. 

Joe DeFazio

Pittsburgh

[Joe DeFazio]

(iPhone accidentally sent this before I finished...last two sentences should read):

Both approaches are valid (as the tens of thousands of professional pianists attest by choosing fine pianos by those manufacturers). So is Yamaha's block fitting.

Joe DeFazio

[Will Truitt]

“If the treble and bass seesaw  back and forth as you tune, with the bass pulling sharp as you tune the treble (and vice-versa), then the "epoxy slathered hardwood wedge shims" may well improve things. 

 

If the out-of-tuneness does not follow this pattern, then the epoxy wedge treatment is not likely to help. “

 

 

Why?

 

Will Truitt

[John Krucke]

n Tuesday, May 7, 2013 5:58:37 PM UTC-4, pianomanpat wrote:

I use a Reyburn tuning pounder to set my strings with.  It does a very, almost too good, job.  You have to be careful with it to not over do it!  Believe me, the strings get set.  And as I said there are other Yamaha pianos in this town that tune up fine and hold their pitch fine with clean unisons.   

I have experienced this same problem with several GB1's. After seating the strings at bridge and hitch pin and pounding away for years the problem persisted. I discovered that the section of string between the bridge and the hitchpin was not set where it crosses the understring felt.

[Dale Erwin]

It can also be uneven crown and bearing

Sent from my iPhone

[Joe DeFazio]

Joe DeFazio wrote:

“If the treble and bass seesaw  back and forth as you tune, with the bass pulling sharp as you tune the treble (and vice-versa), then the "epoxy slathered hardwood wedge shims" may well improve things. 

 

If the out-of-tuneness does not follow this pattern, then the epoxy wedge treatment is not likely to help. “

Will Truitt wrote:

Why?

Hi Will,

Sorry I did not explain my reasoning, so I will do so here.  

In my view, an interesting and relevant question is "how does the pinblock behave under stress?"  Is the pinblock:

1) behaving more or less monolithically (as a rigid structure)

and/or

2) undergoing plastic deformation (being crushed into a fairly permanent new shape)

and/or 

3) undergoing elastic deformation (acting like a spring, deforming and then returning to its original shape)

???

Here are my thoughts on that (I welcome your thoughts or anyone else's thoughts). 

1) [monolithic] - Clearly, there are some cases where a block touches the flange in the middle and not at the ends.  In these cases, the block does tend to act somewhat as a rigid structure, and adding tension to the treble tends to "rock the block" and pull the bass sharp (and vice versa). In these cases, epoxied shims at the ends can be an effective remedy (ending the see-saw motion of the block).

2) [plastic] - Clearly, most or all rebuilders have encountered not-so-well fitted blocks where the maple has deformed over time under the pull of the strings and crushed itself into fitting parts of the plate much better than it did when it left the factory.  I have no data to share about when that deformation occurs, but I would suspect that the "easy" parts (where much stress is applied to a very small area) probably deform almost immediately during chipping, while "tough" parts (bigger contact area) probably take many years to deform.  For a piano with a questionably fit block that is not rocking (touching only in the middle) and that has been strung and at pitch for some time, I don't think that any ongoing plastic deformation will happen quickly enough to cause relatively near-term tuning stability problems (as the OP reports in this case).  So, I don't think that the epoxied shims will help to retard plastic deformation over a time scale of weeks or months. 

However, especially in cases where the upper layer of the block is reasonably well fit but the lower strata are not, I do think that those shims could protect the block from possible eventual delamination problems. So, epoxied shims may be an effective preventative measure. 

3) [elastic] - It seems likely to me that the aggregate pull of many strings on a long section of the block near (but not touching) the flange could cause some elastic deformation. That is, if you could release most of the tension at once (severe plate crack), that section of the block might spring back a bit. 

However, it seems unlikely to me that the aforementioned section of the block would spring back at all while the tension was still applied. I have rebuilt some pianos which had had a long life of tuning stability in which, upon teardown, I discovered surprisingly long areas of zero block/flange contact. If those gaps (towards the middle of the block and not causing end-to-end rocking motion) did not result in tuning instability, then the epoxied shims would not have been needed in those cases. And several of those pianos did not have tuning pin bushings, so all of the elastic deformation would have been concentrated in the block. 

I think that the one place where pinblock elastic deformation may come into play is in flagpoling the pin. The few extra pounds of tension that one may apply with the flagpoling motion might cause some elastic deformation of both the metal pin and the top of the block, which might conspire to un-deform in an inharmonious fashion at some later point in time. 

---

So, I answered yes to all three, but only think the shims help short-term tuning stability in case 1. 

The above is filled with lots of speculation and some anecdotal evidence only, as you can see. If anyone has and wants to share some relevant actual data or experience or reasoning, I am always trying to improve my understanding, so I would welcome your post. 

Thanks,

Joe DeFazio

Pittsburgh

[pianomanpat]

Yes, this piano was made in Indonesia.  I must admit that I wasn't too happy when I saw where it had been made.  Now Yamaha has started making pianos in China and so far, well the ones I've tuned are disappointing.  But all the makers are struggling to survive so I guess they have to do what they have to do to stay in business.  I just also want to say THANKS for all the great input!  I appreciate folks!  Pat B.