Grand hammer hanging question

[Paul Chick]

Jon Ralinovsky wrote:
>
> Hello,
> I'm rebuilding the action for a 1968 Kawai Model 600 (6' long).  The
> hammers are hung in a straight line, but the distance from the hammer
> flange center pin to the center of the hammer molding tapers from 4
> 7/8" in the treble to 5" in the bass.  The top hammers sounded decent
> before I took the action out of the piano; unfortunately, I didn't
> check the case parts to see if I could move the action in or out.  Is
> there any reason that I shouldn't duplicate the original specs?  Is
> it important that all the hammers are hung at the same distance from
> the hammer flange center pin?  If it makes any difference, I did
> change the bore distance of the hammers from 2 3/16" to 2 3/8" in the
> bass and from 1 7/8" to about 2 1/8" in the treble; this was done due
> to the hammers overcentering and the action not being able to be
> regulated.  I look forward to your responses.
>
> Respectfully,
> Jon
>
> --
> Jon Ralinovsky
> Piano Technician
> Department of Music
> Miami University
> 513/529-6548

Jon,

This may be duplicate of what has already been said, but here is the process
that we go through.  There are a couple of questions to ask regarding the
rebuild like:  Was the piano restrung with a new pinblock?  Was the
downbearing changed?  These are two questions of possibly others that is the
reason that we DON'T use the original specs.  Also, the original specs may
not be the best specs for the piano.  Our job is to make the piano sound as
good (minimum) or better than original, not as good or better than when we
got the piano.  If the piano has been restrung, it needs to be brought up to
tension and the strings need to be leveled.  Then measure the distance from
the keybed to the strings.  Take measurements at the ends of each break.
This may vary from section to section or even within the section.  If you
are not compfortable with your readings or suspect some unevenness in the
keybed or the strings, take several readings in each section and look for a
trend.  The bore distance is measured from the center pin of the hammer
flange to the strings.  Measure the height from the bottom of the keyframe
to the center pin of the hammer flange and subtract this from the string
height as measured from the keybed to the strings.

		bore distance  = string height - height of hammer flange center pin

On note #88 with a sample hammer(you should get extras when you order new
hammers) bored to your new specs, put the hammer on the shank without
glueing.  The hammer should fit very snug, so bore accordingly.  Put the new
assembly on the action with the hammer at the original distance from the
center pin and slide the action back into the piano.  Play #88.  Note how it
sounds.  Move the action and/or change the location of the hammer on the
shank to see where the best sound is.  Measure this distance.  This is the
critical distance that you need.  If it is different than original, and very
different in the bass, try the same thing note #1.  The strike point on the
note #88 is a very small window, as little as a 1/16".  In the bass, by
comparison, it is huge.  So this distance in the bass is not as critical.
Set up guide hammers in a straight line between the first note and last note
on the ends of each section, and you're ready to hang hammers.

Paul Chick, Jr.
Plainview, MN