Steinway "pinning" dilemma

[Don Mannino]

Good thoughts, Fred.

I tested Steinway's procedure for action center bushing / pin
installation and fitting when I did a fairly thorough test of procedures
in the 90s.  I bought the same cloth, the heat activated glue, and I
installed and fit them according to the New York factory's procedure, as
outlined to me by someone from the company.  I did not test it with the
Teflon treatment.  These parts all froze up in testing, unless I changed
their procedure to include a final burnishing step.  With the burnishing
they tightened up slightly during torture testing, if I remember
correctly the friction increased an average of 3 grams.

I know that Abel and Kawai burnish the bushings, I don't know about
other companies.  Kawai has a machine to do it, of course.  I think that
Renner does also, but I don't know that for sure.

I hadn't heard that the Emralon treatment actually helps the fit of the
bushing, only that it lowers the friction, allowing a tighter bushing
fit.  It could be that there is some water in the mixture that helps
size the cloth further, or the emralon could harden the cloth some.  In
the 80s I was shown a microscope photo which showed that after the
emralon treatment there were lots of small hunks of Teflon adhering to
the wool fibers, but there was not enough to look like it was filling up
the spaces between the fibers sufficient to change the bushing density.
It might stiffen the fibers up, though, which would make the bushing
seem more firm.  I really should try to get some of the liquid and do
some testing some day.

Don Mannino 

> -----Original Message-----
> From: Fred Sturm [mailto:fssturm@unm.edu] 
> Sent: Friday, October 03, 2003 10:34 AM
> To: College and University Technicians
> Subject: RE: Steinway "pinning" dilemma
> 
> 
> Don,
> 	I hadn't realized there _were_ factories that burnished 
> for final fit. I'm 
> guessing you'll say there is at least one, and its name 
> starts with K ;-)
> 	According to my limited knowledge of manufacture, many 
> manufacturers 
> simply insert the pin in the bushing and use a 
> shrinking/sizing solution, 
> while premium manufacturers would have an intermediate step 
> where they 
> would insert a sizing wire (string a bunch of newly bushed 
> flanges on one), 
> and dip all into solution, then let dry and remove and pin 
> parts together. 
> Come to think of it, maybe I've answered my own question. Is 
> that sizing 
> wire also the burnisher? Removing it being the burnishing 
> process (assuming 
> it's long enough)?
> 	From what I heard Eric Schandall say, this year in 
> Dallas and last in 
> Chicago, Steinway's process also includes dipping/saturating 
> in emralon 
> solution as a last step. He seemed to be saying this in the 
> context of 
> presenting improvements in quality control, and implying that 
> the emralon 
> was quite important in final fit. That it conformed to the 
> pin. He did talk 
> about the possibility of gaining friction somehow over time (without 
> speculating as to why, just saying it did happen), and suggested the 
> solution of applying methanol to dissolve the emralon, hence 
> causing it to 
> re-size to the pins. (And said nothing else would work, as 
> water/alcohol 
> wouldn't be absorbed, and Protek wouldn't have any affect). I 
> had always 
> had the impression previously that the "Teflon II" bushing was not 
> essentially different from any other wool felt bushing as it 
> might behave 
> with Protek saturating the cloth. But after listening to 
> Eric, I am not so 
> sure.
> 	Among other things, I wonder if it is hygroscopically 
> contrary, just like 
> the original teflon bushing was/is. IOW, the bushing is 
> hygrocopically 
> inactive (won't absorb moisture, so won't swell or shrink), 
> but the wood 
> is. So in low humidity, as the hole in the wood is smaller, 
> the bushing is 
> tighter, and vice versa. Just a thought, not based on 
> experience. Regards, Fred Sturm University of New Mexico
> 
> 
> --On Friday, October 3, 2003 8:20 AM -0700 Don Mannino 
> <dmannino@kawaius.com> wrote:
> 
> > List,
> 
> > snip,
>   Factories which burnish the bushing for
> > final fit very rarely will have tightening problems.
> >snip<
> > Don Mannino
> >
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