[CAUT] S&S M Strike point

[Ari Isaac]

If you look at the blueprint drawing of a piano strikepoint scale, you will
see the actual strike point falls between two lines that diverge from n88 to
n1.  At n88 the space between the two lines is 1/64"  while at n1 it is
almost .5".  When I replace a set of hammers on any piano that is accessible
to me, I start with hammer for n85 and dry fit that to enable me to slightly
move it forward and backward along the shank to establish the point of best
tonal results.  That hammer becomes my guide for the high end of the treble
section.  I do the same with another hammer half way down from n85 in the
high treble section to establish another sample and the same procedure,
again, for the low hammer in that section.  I then fill in between the three
samples gluing the hammers in a straight line between those samples.  The
last three hammers from n85 to n88 I glue in in a straight line.I use n85 as
a  starting point because I find it easier to hear than n88 on most
instruments.
Also, I bore the hammer molding so the hammer understrikes slightly when
new.  If the hammer shank, at 90 degrees, is level with the key bed and the
strike point is touching the strings - I move the shank hole 1/16" closer to
the tail to cause that slight understrike.  This is because the hammer gets
shorter over its life time and I want, for most of the hammer's life, to
have it strike top-dead-center. 

ari isaac
 
hand made bass strings and piano hammers
 
416 229 2096
 
isaac at isaacpiano.com
 
http://www.isaacpiano.com
 
http://www.facebook.com/isaacpiano.com

-----Original Message-----
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of John
Delacour
Sent: December-23-12 8:44 AM
To: Bob Hull; caut at ptg.org
Subject: Re: [CAUT] S&S M Strike point

On 22/12/2012 17:20, Bob Hull wrote:

> Does someone know the strike point on string #1 for a Steinway M? 
>  Also, if it has varied over the years, this is for a 1923 model M.
>
> I am building a complete new top action and want to compare that 
> measurement against the current strike line because this piano has had 
> at least one action rebuild in its history.

If your hammerhead is bored at 90° with a bore length equalling the 
difference between the strike height and the hammer centre height then, 
provided your shank length is right, it will contact the string at the 
strike point.  If you are in doubt about the shank length (distance from 
hammer centre to mid-point of hammerhead moulding) then measure this 
length for note 88.  The strike proportion is probably 1/8 at note 1 as 
on the larger models, but if the shank length for note 1 and note 88 are 
the same (probably 130mm) and your hammers are properly bored then you 
can’t go wrong. A few millimetres divergence from some theoretical value 
won’t make a scrap of difference at this point in the scale.

JD