[CAUT] Puzzler: Yamaha G7 clicks

[Fred Sturm]

Hi Alan,
	Maybe so, maybe no, but I have had clicks caused by very minor glue  
joint failure of the knuckle, where it really didn't seem to be loose,  
but turned out to be. So consider experimenting with a bit of thin CA  
(the cheap/fast way of addressing it) in case this can save you a good  
bit of time.
	I have experienced click on release caused by hard knuckle leather,  
though. Chinese piano with player. The owners liked to adjust it so  
that it played very quietly (it badly needed voicing), and the return  
noise was astounding - louder than the "music." Partly this is because  
of the way the solenoids instantly drop when the electrical impulse  
ends (fingers usually don't release the key that fast, especially when  
playing softly). There were other components to the release noise, but  
I traced most of the noise to the knuckle leather. I ran a cylindrical  
object (probably a 1/8" screwdriver shank, or whatever fit, maybe a  
Mannino broach or a paperclip) around between the felt and the  
leather, and it helped a good bit (after trying a number of other  
things, including brushing and needling). In this case the leather was  
very hard to begin with, so I doubt it lasted. (This was not my  
customer, a dealer sent me out to deal with a complaint his regular  
tech couldn't deal with. I more or less satisfied the customer,  
reported my diagnosis to the dealer - needs knuckle replacement, and  
never heard more).
	I don't know if this would help, but it is possible to find table saw  
blades that will widen your knuckle slots the right amount (plywood  
blades, but it takes some experimenting with different brands and  
whatnot to get the exact size slot you want). And then a jig to set  
your shank in and slide it along a fence to make the cut. I forget the  
name of the guy (from CA) who designed and made a couple versions of  
this. It has been discussed on this list in the last few years. Faster  
than a file in the long run, if you do much knuckle replacement. Maybe  
not for an individual piano though.
Regards,
Fred Sturm
University of New Mexico
fssturm at unm.edu



On Jul 26, 2008, at 11:15 AM, reggaepass at aol.com wrote:

> First, let me say that I have never worked on a Yamaha of this  
> vintage before.  The craftsmanship is excellent.  It has Schwander  
> wippens.  First we thought it was hardening of the jack felt  
> punching.  When needling and then replacing that did not solve the  
> problem, we redirected our attention to the repetition lever,  
> brushing, needling, and then replacing the drop screw leather pad  
> ("bumper").  Still no change.  We even tried replacing the piece of  
> action cloth under the repetition lever height adjusting screw  
> (Schwander, right?), just in case that had somehow gotten hard  
> enough over the years to make noise when the lever came back up.   
> Nope, not that either.
>
> None of the keys were chucking (on a sixty-five year old instrument  
> that has probably never had any major servicing!).  I have seen that  
> condition either cause or contribute to this kind of noise before.   
> But if any thing, the balance holes are tight on the key pins.
>
> Your last thought wins you bragging rights, Dan.  We decided to  
> brush some knuckles.  An associateA 0observed that the nap of the  
> leather did not lift as it has on all of the other pianos on which  
> we have brushed knuckles.  So we endeavored to replace the knuckle.   
> The original had a core about 1.6 mm thick, whereas all of the  
> replacements we had on hand—Renner, Abel and Tokiwa—have cores that  
> are around 2 mm thick.  Also, the original slot was too shallow for  
> any of the replacements.  So we used a 2 mm wide file to both widen  
> and deepen the slot.  New knuckle installed (used Titebond Trim and  
> Molding glue, which seems to work well), noise gone. Well, as we so  
> often say in the piano world, “One down, eighty-seven to go!”
>
> We seem to identified the fix, though I must admit that I'm not sure  
> how it is that a hard knuckle could cause this problem.  (Then  
> again, we humans have appreciated sunrises long before we understood  
> what we were actually witnessing when we saw one.)  If anyone knows  
> 1) WHY the hard knuckle leather causes this click on a quick  
> release, or 2) HOW to treat the existing knuckle leather (magic  
> potion, special armadillo comb, etc.), PLEASE do share your insights  
> (hopefully before we file 87 more knuckle slots!).
>
> May this save someone else all of the time we spent trouble-shooting.
>
> Cheers,
>
> Alan Eder
>
>
>
>
> -----Original Message-----
> From: Dan Reed <pianoarts at tx.rr.com>
> To: College and University Technicians <caut at ptg.org>
> Sent: Fri, 25 Jul 2008 8:57 pm
> Subject: Re: [CAUT] Puzzler: Yamaha G7 clicks
>
> In addition to hard jack stop felt....Some more of the usual
> suspects....
>
>
>
> Hard drop screw felt on the rep lever, snapping back on a quick
> release, hitting the drop screw.....
>
>
> 'Chucking key...key bouncing on the balance rail on a quick release...
>
>
> Hard knuckle...bouncing on the jack top...
>
>
> Dan
>
>
> Dallas
>
>
>
> On Jul 25, 2008, at 7:36 PM, reggaepass at aol.com wrote:
>
>
> <excerpt>Yes, you read that correctly, this is a Yamaha model G (not
> C) 7, s/n 3xxxxx.  When the key is released slowly, the click isn't
> noticeable.  However, on a quick release, it is annoyingly prominent.
>  What is the cause?
>
>
> Alan Eder
>
>
>
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