Shanks parallel to strings

[David Love]

How unparallel are you talking about?  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.  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.  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.  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.  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
davidlovepianos@earthlink.net


> [Original Message]
> From: Phillip Ford <fordpiano@earthlink.net>
> To: <pianotech@ptg.org>
> Date: 6/16/2004 2:44:20 PM
> Subject: Shanks parallel to strings
>
> I would like to revisit the idea that shanks should be parallel to
strings at hammer contact.  I know we've had some discussion of this
before.  I looked back through the archives and also in the back issues of
the Journal and couldn't really find what I wanted.  I would like to have
some theoretical reasons why having the shank parallel to the string gives
better action performance than not having it parallel.  The standard
thinking seems to be that the hammer should be perpendicular to the string
line at contact and the hammer should be perpendicular to the shank, which
results in shanks parallel to strings.  I can see reasons for having the
hammer strike perpendicular to the string line.  But I don't see any good
reason for having the hammer perpendicular to the shank or the shank
parallel to the string.  Reasons given in the archives or the journal for
not permitting non-parallel shanks are along the lines of:
>
> 1.  It's bad practice.
> 2.  It reduces power delivery.
> 3.  It won't give as strong a joint at the hammer to shank interface.
> 4.  The regulation will get screwed up.
>
> As to these reasons:
>
> 1.  If it's bad practice, is there some explanation on offer?
> 2.  Why would it reduce power delivery?  The hammer is still traveling in
the same path as it was before - the angle of shank to hammer doesn't
affect that.  If the hammer is still striking perpendicular to the string
why would any reduction in power have occurred?
> 3.  I don't see that the joint should be weaker.  If anything, having the
shank not perpendicular to the hammer would mean that the hole through the
hammer has to be a little longer, which would seem to result in a stronger
glue joint.
> 4.  I can see that this would be true if the action was designed to work
with the shank parallel at contact, and that drastically changing this
would cause various things like rest rails and letoff buttons to be in the
wrong places for the new shank position.  But I'm talking about an action
that was specifically designed to have the shank non-parallel at contact. 
In this case everything could be positioned to work properly so that
regulation would not be compromised.
>
> Any thoughts?
>
> Phil
>
>
>
> Phillip Ford
> Piano Service and Restoration
> San Francisco, CA
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