key sticks

[David Love]

Balance rail pins are, of course, more meaningful as they relate to the
key ratio, front rail pins don't.  The problem with the key ratios has
been because of a production procedure which has not, historically,
indexed the plate into the piano uniformly from piano to piano.  The
determination of the strike point with the hammers glued on at 130mm has
determined the location of the capstan which can, thus, vary and with it
the key ratio.  Those ratios within a given model can vary from .48
(Stanwood measure) to .57 in my experience alone.  That translates to a
significant difference in overall action ratios and results in some
pianos with 2.5 leads at F1 and some with 7.  I don't know how they then
determine the front rail drilling point but presumably it is indexed
from the balance point using some type of template.  A mismeasure or
mismarking seems to have happened.  

David Love
davidlovepianos@comcast.net 

-----Original Message-----
From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On
Behalf Of Kent Swafford
Sent: Sunday, May 29, 2005 5:22 AM
To: Pianotech
Subject: Re: key sticks

Thanks very much. I guess drilling for the balance rail pins in the  
wrong place could also cause the same symptom, but the placement of  
balance rail pins is not meaningless. I just thought someone might  
have some knowledge of production procedures that might give a clue  
as to what happened.

Kent


On May 28, 2005, at 9:45 PM, David Love wrote:

> Don't know for sure but I think they probably just drilled for the  
> front
> rail pins in the wrong place.  Afterall, the location of the pins is
> meaningless except that it centers under the mortise.  Another good
> plate indexing job too that got the capstan back far enough that they
> needed seven keyleads at F1.
>
> David Love
> davidlovepianos@comcast.net
>
> -----Original Message-----
> From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On
> Behalf Of Kent Swafford
> Sent: Saturday, May 28, 2005 5:46 PM
> To: Submit technical files to ptg.org
> Subject: key sticks
>
> I'm sending along 2 pictures of the F1 keystick, B 342631. Note the 7
> original key leads, and the non-original leather key bushings. But
> why I'm writing is the interesting location of the wear in the key
> bushing from contact with the front rail pin. The whole set of keys
> is similar, and under certain circumstances the front rail pins do
> indeed bind on the front of the mortise. (This explains a few things!)
>
> Any ideas out there with regard to what happened? It looks like the
> mortise is in the wrong place by just over 1/16". Anything else to
> watch out for? I know, I know -- watch for  _everything_. But it
> probably is just the mortise in the wrong place, right?
>
>
> Kent
>
>
>
> Photos at:
>
> http://tinyurl.com/cyygq
>
> http://tinyurl.com/ao697
>
> Direct ptg.org URLs:
>
> https://www.moypiano.com/ptg/files/attachments/01/b9/bc/70/ 
> DSCN1071.jpg
>
> https://www.moypiano.com/ptg/files/attachments/fa/4b/57/a0/ 
> DSCN1075.jpg
>
>
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>
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