Shanks parallel to strings

[Phillip Ford]

>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