Rebushing centers/mystery center pinning

[Horace Greeley]

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Hi, Barbara,

At 08:11 PM 12/9/2004, you wrote:
>Robin,
>
>Do you think if I did some tests on pieces of bushing cloth, I'd be able 
>to tell anything?

Yes - but, not as much as if you try it on some test parts...I think I 
might be inclined to try some scraps and then some test parts...just as a 
didactic exercise, if nothing else.

>  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.

The above would certainly help you discover what works and what 
doesn't...AND...you could share that with the rest of us!

>  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.)

Lots of venitlation...

>  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....   :-)

They won't stay there long...it's a design feature of the system.  As Robin 
so accurately notes:

"I think, once resigned to rebushing, you have nothing to lose."

FWIW, I completely concur.

Best.

Horace


>----- Original Message -----
>From: <mailto:hufford1@airmail.net>Robin Hufford
>To: <mailto:pianotech@ptg.org>Pianotech
>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.
>      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.
>      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.
>        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.
>       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.
>       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.
>        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.
>Regards, Robin Hufford

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