[pianotech] D Hammers

[George F Emerson]

----- Original Message ----- 
From: "John Delacour" <JD at Pianomaker.co.uk>
To: <pianotech at ptg.org>
Sent: Tuesday, April 20, 2010 4:30 PM
Subject: [pianotech] D Hammers

>But in order to strike on the line the heads in the bass will need to be 
>angled slightly to the right and in the tenor slightly to the left, which 
>is to say that the hammer rail is not drilled to the strike-points, and 
>this is the question :  did Theodore Steinway have a good scientific reason 
>for not doing so.  Did he believe that the greater the bore angle of the 
>hammer and the angle of the strings the more the hammer-head needs to be 
>rotated on the shank?  Was he right, and if so, why does no other maker, so 
>far as I know, do the same?

I cannot speak for Theo, but this is done quite deliberately by Mason & 
Hamlin, and by pianos of my design for Hailun.  There could be others, of 
which I am not aware.  The reason is that the tail of a bass hammer bored at 
an angle, rotating on its axis and moving between its neighbors, will move 
into closer proximity to the hammer at its left, if the hammers are hung 
perfectly vertically.  With tenor hammers, angled in the opposite direction, 
the reverse is true; when a hammer is raised to its strike point its tail 
comes into closer proximity to the angled hammer to its right.  Tapering the 
tails and wider spacing of the notes helps with this clearance problem, but 
mounting the hammer at a slight angle, left or right, adds another measure 
of security in hammer clearance.  This practice does introduce a bit of a 
problem with mating the hammers to the strings.  In voicing a bit more felt 
has to be removed from one side than the other to mate perfectly with the 
strings in bichord and trichord sections.

Try this.  Dry fit the first three tenor hammers on their shanks, as 
perfectly vertical as you can make them.  Lift the center hammer and shank 
up to its strike point.  It looks like an optical illusion, but you can 
clearly see the hammer TAIL of the raised hammer get closer to the hammer 
HEAD to its right, and move away from the hammer HEAD to its left.  As the 
hammer shank approached a horizontal orientation, the tip of the tail is not 
only moving upward, but also outward, away from the front of the keyboard, 
by about 6.5mm.  If you draw a line on the side of the first hammer, 
representing the centerline of the hammer, and a second parallel line at 
6.5mm out from the hammer flange, you can see the hammer tail of its 
neighbor move away from the centerline and toward the parallel line, as it 
is raised.  Due to the angle of the hammer bore, the hammer tail moves 
closer to its neighbor that is angling in its direction.  Now, experiment 
with angling the hammer mounting to slightly off from vertical to the left, 
until hammer tail of the center hammer is perfectly centered, when raised, 
between the neighboring hammer heads.  That is the angle intended by this 
design concept, and calculated to produce a slightly different action scale 
than the strike point scale.  Measure the horizontal distance between the 
strike points of the last bass note and the first tenor note.  Then measure 
the distance between the hammer flange screw holes for these two notes.  If 
the later measurement is greater, this is probably what was intended.

It could be argued that this tiny angle could rob the hammer of some of its 
power in delivering a direct blow to the string.  It could also be argued 
that it could produce uneven wear on the hammer centers.  In my experience, 
I have not seen these to be problems.

Frank Emerson