Shanks parallel to strings

[David Love]

One problem with boring at the actual string height dimension is that you
may not get the hammers under the block in the bass.  That is a problem on
some of the older Bechsteins that are short-bored.  I would check that .  I
tend to want the hammer hitting at 90 degrees to start.  If the hammers are
short bored you can determine the rake with a let-off rack.  Set up the
action with end shanks on each section.  Slide it under the let-off rack
set to the string height for that section.  With your hammers bored based
on clearance and rest rail height etc.., slide the hammer on the shank on
the end of section and raise the hammer up to the let off rack.  Drop a
square off the let-off rack and rock the hammer back and forth until you
find the position where the moulding runs parallel to the square.  You will
have to overream a bit to get some play.  Then glue on the end hammers of
each section using this method and hang the rest of the hammers between
using yourthem as a guide.

David Love
davidlovepianos@earthlink.net


> [Original Message]
> From: Phillip Ford <fordpiano@earthlink.net>
> To: <pianotech@ptg.org>
> Date: 6/17/2004 12:04:26 PM
> Subject: RE: Shanks parallel to strings
>
> >How unparallel are you talking about?
>
> For talking purposes, let's say as unparallel as you like.  I think we're 
> agreed that a long bore will cause performance problems, although I'm not 
> sure that we haven't concluded that based on using long bore hammers on 
> actions that weren't designed to accomodate them.  If you deliberately 
> designed your action to have a long bore would there be a performance 
> degradation?  If so, why?  So far I haven't heard anyone offer a 
> performance reason for not using a short bore.  There's going to be some 
> lower limit for a short bore, which will be dictated by the physical 
> dimensions of the hammer (I think that you don't want to drill through
the 
> felt) and by how far above the keybed you wish to place your string plane 
> (I think the piano might look peculiar if the rim were 3 ft tall, but I 
> suppose that's personal taste).  Would there be a performance degradation 
> or improvement from using a short bore?  If so, why?
>
> >   If the hammer is radically non
> >perpendicular to the string then it will be striking askew and not on the
> >strike point.  That might stress the glue joint as the force would be
taken
> >at the joint rather than straight through the hammer moulding.  The
voicing
> >would be another issue.
>
> As I mentioned before, I can see that there are reasons for the hammers
to 
> strike perpendicular to the strings.  These are among them.
>
> >   But if the hammer is perpendicular to the string
> >at contact then I don't think it makes much difference as to whether that
> >shank is parallel to the string or not.
>
> I think I agree.
>
> >   There are many examples of pianos
> >(older Bechsteins come to mind) that are short bored and the hammers are
> >raked out.  It may cause a slight raising of the let-off button and drop
> >screw.  But I haven't run into one that couldn't be regulated.   You can
> >even argue that with the hammer shank starting in a higher position it
> >minimizes the change from a horizontal to a vertical vector (do I have
that
> >right) and the action will actually weigh off slightly lighter due to a
> >reduction in friction.
>
> This could be an argument in favor of a short bore.
>
> >   You can even make the argument that since shanks
> >tend to flex on the way up, that slight short boring without the rake is
> >justified since that will likely result in the hammer hitting
perpendicular
> >to the string.
>
> I've heard this before and think that there could be something to it.
>
> >   For those reasons, if you are going to err, err on the side
> >of short bore as opposed to long bore.  Though I always aim for the
hammers
> >perpendicular to the string at impact, minor variations are not likely to
> >cause a great deal of trouble.  As far as shank parallel to strings,
it's a
> >reasonable standard that usually allows everything else to fall in line.
> >But in and of itself, much ado about nothing.
> >
> >David Love
>
> In and of itself I agree.  If it's a result of deliberately short boring 
> the hammers, I wonder if it's a bad thing.
>
> Although I think this is an interesting theoretical topic, the reason I 
> bring this up is because of a Feurich 220 in my shop on which I was 
> planning to replace the hammers.  The piano belongs to me, so I have some 
> leeway in what I do with it.  I was planning to replace the worn Renner 
> hammers with Ronsen Wurzen hammers.  This is a high quality piano that in 
> my opinion is a standout in terms of action feel and response.  It also
has 
> a nice tone even with the worn hammers.  When I ordered the new hammers I 
> measured the existing hammers, assuming that they would be 'correct',
given 
> what I've said above about the piano.  Before boring the hammers I
checked 
> the string heights and hammer center heights as I routinely do.  The 
> dimension that I calculate from this usually matches the existing bore 
> dimension fairly well.  If there's a difference I assume that they were 
> supposed to match and bore the hammers at the calculated dimension.  In 
> this case there was a dramatic difference.  The calculated dimensions 
> were:  bass - 2 3/4 inches, treble - 2 5/16 inches.  The existing hammers 
> were bored at:  bass - 2 3/8 inches, treble - 2 1/8 inches.  The existing 
> hammers are also glued at 90 degrees to the shanks.  This means that in
the 
> bass the shanks are about 4 degrees above parallel at strike and the 
> hammers are fairly dramatically overcentering.  If this were a cheap or 
> horrible sounding piano I would assume this was all a mistake and go
about 
> trying to change it.  Since this pianos sounds good and plays so well I 
> have to wonder if this wasn't deliberate and if they know something that
I 
> don't know.  And it makes me question the mantra of hammer 90 degrees to
> string and hammer 90 degrees to shank.
>
> Phil Ford
>
>
> > > I would like to revisit the idea that shanks should be parallel to
> >strings at hammer contact.
> > >
> > > Phillip Ford
>
>
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