Steinway Agraffes

[A440A@aol.com]

Dale writes:

<<   All the 7/32 " replacement  agraffes out there from piano- tek,Steinway 
or where ever are, I believe, of  German origin & none that I've measured are 
the actual size of the originals  but slightly smaller as you say. We still 
use them however & I've  cranked em sufficiently tight without ever a one 
being 
stripped. <snip<
   Do you have a supplier with a true dimensioned  part? If so I'm all ears. 
>>

   No,  I was told that they "all" come from the same place.  The last time I 
installed a new one that felt too loose, I had it tear out as the trichord 
was brought up to tension.  This may have been an excessively loose drilling in 
the plate combined with the undersized agraffe.  I went to an old one for 
replacement and everything was fine.  


Ron writes: 
<<This didn't compute at the time, and still doesn't. The threads should be 
about 0.020" deep (x2 for the diameter), so I don't see how 0.003" less 
thread depth could make a difference. There should still be plenty of 
thread overlap unless the plate was screwed up. Did you happen to measure 
the inside diameter of the tapped plate holes? They should have been well 
under 0.190".<<

    No, I didn't measure the ID of the plate. I was just aghast at the wobble 
in the fit, even when the agraffe was nearly all the way installed.  I have 
measured thread dia. as small as .210" in some new agraffes, in which case, 
there would be 20% less thread involvement compared to a full size.  So, when I 
considered that the remaining engagement is on the very thinnest part of the 
thread, it wasn't so surprising that I had a failure.  
     The question I still have is, Why do they make them so much smaller, the 
originals are usually right around .217" and fit quite nicely.  I don't know 
of any other supposedly high quality threaded pieces that are so far off the 
stated spec.  
Regards, 

Ed Foote RPT 
http://www.uk-piano.org/edfoote/index.html
www.uk-piano.org/edfoote/well_tempered_piano.html