repetition/backcheck problem

Ron Torrella torrella@umich.edu
Thu Aug 20 07:25 MDT 1998


On Thu, 20 Aug 1998, Robert B Edwardsen wrote:

> Jim Coleman, Sr. wrote:
> 
> > Hi Don:
> >
> > Did you by any chance shorten the hammer boring distance in order to get
> > a longer tail? This could cause all kinds of problems.
> >
> > Please understand, I'm not criticizing you. You may have just copied the
> > problem that was there from before.
> >
> > Jim Coleman, Sr.
> >
> 
> Hi Jim:
> 
> Do you always bore your hammers in relation to string height rather than
> copying the original (of course compensating for wear)? 
> 
> Rob Edwardsen

Hammer bore is determined by taking the string height, subtracting
hammershank flange centerpin height (from the keybed -- in the piano!),
and adding a tiny amount (I add 1/32") to take into account filing.
Copying the original bore distance would be next to impossible because you
don't know how much felt's been removed.  Even so, copying the original --
if it was wrong from the git-go -- just isn't a good idea.  If you replace
the pinblock and the new one it thinner or thicker than the original, you
may have changed the string height.  That would throw off the original
boring specs.

Ron Torrella, RPT
Piano Technician
University of Michigan
School of Music



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