Hammer bore dimension

[David Love]

Measure the string heights, for example, at either end of the agraffe
section, let's say hammer 21 requires 1 13/16" bore and hammer 53 (or
whatever) requires a  1 7/8" bore.  Measure and mark the bore distance
on the end hammers.  Now clamp them together in the same manner you
would to gang file them.  Make sure that the strike point end for this
group is in a straight line by butting it up against something solid.
Now take a straight edge and using the bore markings on the end hammers
(21 and 53) as a guide, strike a line  through the group of hammers
which will give you point at which you will bore on each hammer.  Do
that for each section, bass, tenor, 1st and 2nd capo.  When you use the
boring guide (I use the Renner one) you will have to eyeball where the
drill hits the mark instead of using the premeasured gauge.  In this
case, a brad point drill will be the most accurate.  Assuming that the
string heights don't undulate (which they might) you will then have
bored the hammers to the precise string heights within each section.  If
the string heights vary from section to section it doesn't really
matter, you will capture it accurately this way.  If you are using a
non-Steinway hammer, like a Ronsen, order them not cut to length.  Once
you have bored them, you can then cut the tail lengths to exactly 1" by
making a small jig with a dowel that indexes off the hole you've just
bored.  That will help give you uniform checking.  After you have cut
them to length, cove them with a Forstner bit and then shape the tails.


David Love
davidlovepianos@comcast.net 

-----Original Message-----
From: pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org] On
Behalf Of Phillip Ford
Sent: Thursday, November 04, 2004 4:27 PM
To: pianotech@ptg.org
Subject: RE: Hammer bore dimension

>Vary the bore for each section.  Measure the first and last string
>height in each section and bore accordingly.

So, are you saying that you use a constant dimension within a section,
and 
vary the dimension from section to section?  Or, you vary the dimension 
also within the section?

>You can line up the
>hammers with the strike point flush and strike a line marking your bore
>spot for each hammer.

That went over my head David.  Would you mind trying again in other
words?

>The reason to vary the bore is so you get uniform
>regulation, i.e. aftertouch with all else being equal.

That was my reasoning as well.  I was wondering if there was something I

was overlooking.

>I don't know if
>this is a Steinway but I typically find that the plate dips on the
>treble side and the bore dimension must gradually decrease at that end.

It is and it does.

Phil Ford

>In the middle of the piano with only a 2 mm differential between high
>and low, I might pick an average.  But, to be precise, bore for string
>height variances.
>
>David Love
>davidlovepianos@comcast.net


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