Accu-just Hitch pins - any time, any place!

[Delwin D Fandrich]

----- Original Message -----
From: <BSimon999@AOL.COM>
To: <pianotech@ptg.org>
Sent: Tuesday, August 17, 1999 11:00 AM
Subject: Accu-just Hitch pins - any time, any place!


> I find it amazing that most of the technicians I have been reading think
that
> Accu-just hitch pins can be put in any place in any plate.  Drilling holes
> for these pins can weaken a plate, especially when they are put in the
line
> of where the old hitch pins were placed. PERHAPS Baldwin knows better than
> these technicians and PERHAPS they designed to plate to take the stresses!

Yes, Baldwin did make some changes when they switched to vertical hitchpins.
Among those changes were the thickness of the hitchpin panel and the
placement of the hitchpins on the panel.  The pins are now staggered so that
they are not in line.



> I know of two pianos that catastrophically failed when Accu-just hitch
pins
> were installed. In both cases the plate broke off at the hitch pin line
> before the piano was even up to pitch. These failures were  back when
> Accu-just hitch pins had just been introduced, but the pianos currently
being
> "upgraded" with new pins were not designed for this type of replacement.
> There is not only degradation of the plate strength due to removal of
> material, but also the leverage effect of not having the strings sit at
plate
> level. Any other disasters out there?

I have heard of a couple.  Perhaps the same two that you are referring to.
I have never personally seen one of these or directly known anyone it has
happened to.  Hearing about them is enough for me, however.

Having said that, we do modify plates to accept these pins on a fairly
regular basis.  I don't know how many we have been done this way -- a few
dozen, at least.  It is done more often in the bass where the benefits of
the vertical hitch are most noticeable. I have yet to see a bass hitchpin
panel that is not strong enough to take whatever added stress the vertical
hitchpin might introduce.

As well, we are very cautious to spread the load out when we do install them
in the tenor/treble sections.  We keep the string placement on the pin
fairly low -- 4 to 5 mm above the panel surface is typical.  Note that the
aliquot bar used on Steinway grands is 4 mm high.  Not quite the same
stresses, but close.  Compare this to some Baldwin grands I have encountered
in which the string is placed as much as 12 to 14 mm above the plate
surface.  In these pianos the vertical hitchpin really was used to make up
for either bridges that were too tall or plates that were set too low.  And
the stresses are very high.  We do not use them this way.

We locate the vertical hitch in the same location as the original if
possible -- and if acceptable acoustically.  We do not normally use the
typical slotted spring pin, but the groove-lock pin I have described
elsewhere instead.  The pins we use are of smaller diameter than those used
in the Baldwin pianos and drilling for them does not reduce the strength of
the plate appreciably.

As I said, we have yet to have a problem and the benefits are noticeable.



> Come on you engineers and physicists, - tell me why replacement is all
right!

I consider anything to be all right if it does not damage the piano and it
improves the performance.  Used correctly these pins meet that criteria.  In
certain pianos they can substantially improve the acoustical performance.
Used incorrectly they can -- and reportedly have -- cause problems.

Regards,

Del
Delwin D Fandrich
Piano Designer & Builder
Hoquiam, Washington  USA
E.mail:  pianobuilders@olynet.com
Web Site:  http://pianobuilders.olynet.com/