Backcheck height

[A440A@aol.com]

Avery writes: 
>newest D. I don't know if it was done that way at the factory or at the
>dealer but the backcheck height is appreciably too high. I've had "clunking"
>noises from the hammer shoulder rebounding on it; notes failing to repeat
>in a very fast repetitive "situation" (had complaints about it), because the
>shoulder was getting hung up on the backcheck 

  Greetings, 
    I have seen this problem before, also.  The fix?  a sharp knife!  The 
very lowest portion of those hammers are probably solidified with lacquer, and if 
not, you can go ahead and soak them sufficiently to keep the felt from moving 
around.  Then, take a utility knife and carve as much felt out of the way for 
clearance.  It won't take off enough to worry about weight changes,(given the 
surrealistically erratic SW found on factory hammers), and the hammer 
integrity won't suffer if there is a solid matrix of felt and lacquer down there.  
  

>(I couldn't make the hammer
>check high enough because the checks were too high), plus what has  already
>been mentioned about the tails rubbing on the backchecks. 
>>I'm going to replace the backchecks and wires and set them so that the tail 
at letoff
>is app. 2 mm. above the backcheck, assuming the hammer bore distance is 
correct,
>of course. :-) 

   Often, when there are tails rubbing leather, (mmm, sounds like a x-rated 
cowboy movie) and hammers bouncing off the checks, I have found that the 
inter-relationship of back-check angle and tail shape are the root problem.  I would 
suggest that you take a few of the hammers and shanks off, and with a 
divider, check to see if the curve of the tail matches a radius of 2 9/16".  If not, 
then see if there is enough wood left to allow you to re-carve them to this 
radius. Sometimes the factory hammers are shaped with a significantly smaller 
radius and the tails drag at about their middle.   
   Once done, see that at rest the backcheck is leaning distally slightly 
beyond a 90 degree angle to the shank.  This is a good starting point.  Assuming 
a proper keydip, you should be able to get the hammers to check no more than 
1/2" from the strings with no bouncing off. 
Let us know what happens, 
Regards,  
 
Ed Foote RPT 
www.uk-piano.org/edfoote/
www.uk-piano.org/edfoote/well_tempered_piano.html
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