hammer bore distance

[A440A at aol.com]

<< >...I am wondering what  would be considered  reasonable tolerances 
>in the ideal bore distance? >>

Greetings, 
   Reasonable for what?  As an action demo model, it is fine as it is.  
Maximum efficiency in energy transfer happens around perpendicular, so within a mm 
of that, (on the plus side) seems fine, (in that I cannot hear a difference in 
1 mm of hammer angle change).   I regularly hang hammers 1 mm long at the 
school, since 18 mos. later, after the first filing,  they are usually exactly 90 
degrees.  From there on, they wear out as they shrink, and we do it again.  
But we got the best out of them in the first 5 years.
  regards,
 
Ed Foote RPT 
http://www.uk-piano.org/edfoote/index.html
www.uk-piano.org/edfoote/well_tempered_piano.html
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