Rebushing centers/mystery center pinning

[Barbara Richmond]

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Robin,

Do you think if I did some tests on pieces of bushing cloth, I'd be able =
to tell anything?  I was thinking in particular about the 90/10 acetone/ =
CA mix and also trying out some with a bit of methyl alcohol mixed in, =
too.  Does anybody know if I'll blow up or pass out or anything?  (That =
last one is the important one, I'm not a chemist.)

I repinned some again yesterday, following very precise directions by =
folks who should know.   I was more aggressive in my burnishing and =
working the flanges and just generally pinning tighter, but by this =
morning, they had loosened some (I measured each step using my gram =
gauge).   The flanges went from too tight before working the flange, to =
the high end of being acceptable after working the flange. This morning =
they were at the low end of acceptable--which is OK as long as they stay =
there, but I have a funny feeling they won't stay there for long.  After =
this test of my pinning technique, I have come to the conclusion that =
perhaps I'm not totally incompetent after all----maybe just =
partially....   :-)  =20

Barbara Richmond


----- Original Message -----=20
  From: Robin Hufford=20
  To: Pianotech=20
  Sent: Monday, December 06, 2004 1:31 AM
  Subject: Re: Rebushing centers


  Hello Barbara,
       I think it is vital to properly shrink and stabilize  the =
bushings after installation.  Otherwise, you will be where you are now =
with the inadequate Steinway parts (something ridiculous and telling in =
itself for a company in business doing this for 150 years,)  you refer =
to in recent posts, that is, the friction will not be stable and the =
hammer will also wobble causing a loss of power. =20
       I have used shrinking fluid combinations with proportions ranging =
from 50/50  to 75/25 or so, water and methyl alcohol and had good =
results. Although, I have had, on occasion, a need to do some over, as =
some were still, after drying, loose.  These were then rendered =
acceptable after another treatment. =20
       An interesting new possibility, which had occurred to me one day =
as I was waiting for a conventionally treated set to dry and is, as far =
as I can tell, a completely new technique since I have not seen it =
referred to anywhere or heard any discussion about it elsewhere,  I =
decided to try  on a set of Tokiwa  shanks which had a very soft, =
unstable bushing that responded to pining exactly as you describe with =
the Steinway, is, perhaps, better.  =20
         This method uses water thin CA glue thinned even further to =
about about a 90/10 acetone/glue mix.  It occurs to me now,  as I write =
this,  that it may work better if a little methyl alcohol is added as a =
wetting agent, if possible, although I haven't done this.  There may be =
complications if alcohol is used which I am unaware of at the moment.=20
        As you know, of course, the CA rapidly sets and this =
characteristic obviates the need for the prolonged drying necessary when =
using water.   One can vary the mixture as desired to control its =
effects,  but if too much CA is used it will make the bushing so hard =
that it will click and this defeats the purpose of  its use.  Too little =
and there is not enough stability induced in the bushing. =20
        On the piano I tried this on I have had very good results;  the =
pining is stable and there was a noticeable increase in power.  I tried =
at first to apply it simply by dripping the mixture onto the bushing:  =
this does have an effect, but, eventually, I removed the pining, wetted =
the bushing and then reinstalled a pin.   Perhaps,  as I indicated =
above, a wetting agent like methyl alcohol will make it possible to do =
this without even removing the pining.   All of the flanges on this =
piano had already been repinned, some twice or even three times.  They =
had progressively loosened as you described earlier. =20
         Judging from your recent posts you are considering rebushing =
the inadequate Steinway shanks you have referred to.  I would try this =
technique before rebushing were this problem one I had to solve.  I =
think, once resigned to rebushing, you have nothing to lose. =20
  Regards, Robin Hufford=20


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