[CAUT] center pinning changes/ long pin method

[Wolfley, Eric (wolfleel)]

Jim,

I'm sure your centering jobs would last 100 years if the instruments
were only played only on holidays...also, the hammers and parts on these
earlier instruments weigh quite a bit less which would lead to less
stress on the bushings.

Eric

Eric Wolfley, RPT
Head Piano Technician
Cincinnati College-Conservatory of Music
University of Cincinnati
-----Original Message-----
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of
Jim Busby
Sent: Thursday, September 13, 2007 2:10 PM
To: College and University Technicians
Subject: Re: [CAUT] center pinning changes/ long pin method

Jon,

After 17 hours pounding per day for three years by vigorous piano majors
most of our hammer centers get loose. That's why I went to the long pin
method. If your method truly gets more than twice the "life" that ours
do I'd certainly like to try it! While bushing cloth is not felt (you're
right) it still may have fibers that act like felt in that they can be
"combed". I dunno. It seems that with the long pin method (one direction
only) there seems to be small strands of fiber sticking out the exit
side of the bushing.

Thanks for your input. I'd like to learn more and see how I can make my
bushings last 100 years! (I'd settle for ten)

Jim Busby BYU  

-----Original Message-----
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of
John Delacour
Sent: Tuesday, September 11, 2007 1:22 PM
To: College and University Technicians
Subject: Re: [CAUT] center pinning changes/ long pin method

At 10:31 -0600 11/9/07, Fred Sturm wrote:

>In burnishing center felt, it seems to me that the burnisher is 
>going to be pressing against the felt hard enough that fibers 
>wouldn't be able to move around, at least significantly. At this 
>point in my own work I mostly do a rapid back and forth action, fast 
>enough and enough of them to create a good bit of heat. (You can get 
>heat pulling the burnisher through all the way rapidly, but  I think 
>I get more heat faster by doing back and forth, as the metal of the 
>burnisher heats up). That seems to set the felt quite nicely. And it 
>seems to be possible to move up a half size to a full size just 
>using burnishing action without removing any felt, just the ironing 
>action. I haven't been doing it this way long enough to have a good 
>sense for longevity and whatnot, but it seems to be good so far. 
>Certainly makes sense, as long as the felt in the bushings doesn't 
>swell later, maybe due to humidity rise, and make the centers 
>sluggish, and I haven't found that in university pianos, which get 
>quite a bit of use. Of course I am dealing with my own humidity 
>environment, which is typically 10% to 60% range.

For a short while a long time ago I did burnish with a smooth broach, 
creating more or less heat, but I quickly gave that up and now never 
burnish or do anything that will "iron" the bushing cloth (it is not 
felt!).  Any heating or pressing of the cloth produces very 
unpredictable results.  I strongly deprecate such a practice.  If it 
has been done, it would be best to leave the bushings unpinned for a 
day or two before commencing centring.

Before I start a centring job I make sure that the parts have 
acclimatised to normal room environment by keeping them there for a 
day or two.  I use a broach about 5" long roughly the same size as 
the new pin and roughen it so that I will achieve the desired degree 
of friction with about five passes.  If the broach is too slow I 
roughen it more and if it's too fast I dull it with a few strokes of 
sandpaper.  To use a broach that is too dull and requires ten or 
twelve passes is simply a waste of time and energy, and too sharp a 
broach does not allow the fine final adjustments unless very special 
care is taken.

When I started out in the trade I used to use talc for lubrication as 
well as the trace of oil from dragging the pin through my hair, but I 
now use no magic powders and have no plans to use teflon or anything 
else.  As Ted and I have mentioned before, it is common to find a 
well-used piano a hundred years old whose centres are still very 
good, and yet here I read of someone recentring every few years, 
presumably using some modern method.  At that rate the action will 
not reach 20 years, let alone a hundred!  If I needed to re-centre 
after ten years I would severely question my methods and materials.

JD