hammer mass (was Wurzen felt)

[David Love]

Yes, it seems that it is not a pure test.  It was interesting, however, to
observe the difference.   It brings something else to mind, which is what
happens when, say, a new action with 7/16" shanks is combined with a hammer
weight from the original design which utilized 3/16" shanks and of a
different species of wood.  My own experience does suggest that a light
hammer on a 3/16" maple shank does not sound the same as that same hammer
on a hex 7/16" shank made of hornbeam.  

David Love
davidlovepianos@earthlink.net


> [Original Message]
> From: Stephen Birkett <sbirkett@real.uwaterloo.ca>
> To: Pianotech <pianotech@ptg.org>; <davidlovepianos@earthlink.net>
> Date: 5/12/2003 9:18:36 AM
> Subject: hammer mass (was Wurzen felt)
>
> David Love scripsit:
> >  I have had an experience on the other end fo the spectrum.  I
> >have a customer with a Hamburg Steinway A (newer one).  She wanted the
> >action heavier so a previous technician put clips on the shanks.  Though
> >she liked the weight, the tone became very unpleasant to her and others
who
> >heard the piano.  I suggested we try removing the clips (she had not made
> >the connection), fortunately an easy thing to do.  The tone that she had
> >loved about the piano returned.  A match of hammer weight to the
soundboard
> >assembly (and the relative density of the hammer, perhaps), is clearly
> >important.  Heavier hammers do not always sound better, as I have often
> >heard stated here.
>
> An interesting experiment, for sure, but putting clips on the shanks 
> is not the same thing as simply "increasing hammer mass". The clips 
> will certainly affect the resonsant frequencies of the shanks which 
> may well have been a significant contributor to the tonal change. We 
> don't yet have general relationships which connect shank flexibility 
> to tone, but there's plenty of anecdotal evidence about this, and 
> shank resonances are a proposed mechanism.
>
> How to increase mass without altering shank resonance frequencies? 
> You can't because *any* change in mass distribution of the 
> hammer/shank system will influence these. Even adding or removing 
> mass to (from) the hammer core may influence tone by altering the 
> strike mass/string relationship, or by altering the shank/hammer 
> resonances, or both. These are different phenomena. Unfortunately the 
> nature of piano action mechanism makes it impossible to adjust 
> independently only the strike mass/string mass relationship [which is 
> what will be generally understood by "adjust the hammer mass"].
>
> Ah...the complexities of our difficult friend the pianoforte.
>
> Stephen
> -- 
> Dr Stephen Birkett
> Associate Professor
> Department of Systems Design Engineering
> University of Waterloo
> Waterloo, Ontario
> Canada N2L 3G1
>
> Davis Building Room 2617
> tel: 519-888-4567 Ext. 3792
> PianoTech Lab Ext. 7115
> mailto: sbirkett[at]real.uwaterloo.ca
> http://real.uwaterloo.ca/~sbirkett