[pianotech] boring, (was Hammer strike line)

[Randy Chastain]

Wow, Dale!

Strike line and sound production is really a very interesting subject  
and one worth researching, documenting everyone's experience and  
trying to define. No wonder why I was struggling, with the soundboard  
involved and all. I can't do anything about soundboards because I  
don't do them. I have noticed and thought about the string height in  
that section. I'll have to go back and measure. I just did a hammer  
job on a Steinway L 1929. Turned out good but not great in that area.   
When I measure the string height there is a difference by section and  
I believe ( memory) the killer octave height is greater.  I am so  
grateful for t  his group. There is no place else we can share piano  
stuff like this with you all. Thanks.


Randy Ellen Chastain
San Francisco Bay

On Feb 8, 2010, at 7:57 PM, Erwinspiano at aol.com wrote:

>    Hi Ed
>   What do you find the average amount of over centering to be ie.  
> no. of MM s the center of the hammer shank rises above the center  
> pin height?
>   Also I am most curious as to your subjective opoinion about what  
> discernable differences in sound..if any?
>     uhhh...and the shank is parallel to what zzzzactly?
>   Thanks Pal
>    Dale
>
>
>
> -----Original Message-----
> From: Ed Foote <a440a at aol.com>
> To: pianotech at ptg.org
> Sent: Mon, Feb 8, 2010 7:51 pm
> Subject: Re: [pianotech] boring, (was Hammer strike line)
>
> Dale writes:
>  Perhaps the idea Ed was getting at was that whatever degree the  
> string slope is that there should be a corresponding  amount of over  
> centering and rake so the string and hammer are at right angles to  
> each other ant the keybed. However this means calculating the slope  
> on each piano or just checking it and averaging the bore. I think I  
> just devised an A B Expereiment. I'll work on it
>
> I do calculate the bore distance to the slope. I do this by using a  
> set of graduated "hammers" glued up to shanks and flanges.   
> Actually, the "hammers" are various lengths of the Renner slats,  
> glued to the shanks at exactly 90 degrees.  By putting, say, a 49 mm  
> "hammer" in the piano, I can simply lift it to the string, drop a  
> square down along its edge, and instantly see if it is at right  
> angles to the string. When I find the correct length, I know that  
> upon contact, the hammer is at 90 degrees to the string, and the  
> shank is parallel.  It is quick, accurate, and easy.
> Regards,
> Ed Foote RPT
> http://www.uk-piano.org/edfoote/index.html
>

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