Hallet & Davis bridge agraffes back

[Delwin D Fandrich]

Richard Moody wrote:

> My guess is,  this alternating of high and low back bearing on the
> agraffes is to equalize the vector forces.

I saw one of these pianos in which all of the holes went from low in front to high
in back.  At least they did when the piano was built.  When I saw it the bridge
was split wide open and the agraffes pretty much all floated free.  Alternating
the holes equalized the forces and kept the bridge from rolling and/or breaking
open.


> I believe the speaking length
> holes are on the same line, and provide an over all down bearing.

 Not always.  I've also seen at least one instrument in which the c/l of the hole
through the agraffe was in a constant plane but the both the speaking side and the
backscale side alternated.  The overall bearing would have been equalized but half
of the strings were higher than normal with the other half being lower than
normal.


> The
> position of the rear holes alternating high and low (above and below the
> spk length side holes) is a puzzler. The rear bearing point is the same as
> in all pianos, a ridge capped with felt.

They had to handle the offset somehow.  They were looking at the averages here.


>          It seems to me these holes provide a "swagger" much like bridge pins,
> execpt it is in the vertical mode rather than the horizontal. The swagger
> is to prevent strings buzzing inside the agraffe. I bet they found out the
> hard way, agraffes with holes straight through buzzed like crazy.

Probably so.  There does have to be some offset to adequately terminate the
speaking portion of the string.


>  Rather
> than give up, Geo Davis, (my guess as to the brains behind this) some how
> conceived the idea of drilling the holes slanting down. But after he
> installed these while there was no buzzing, the bridge must have had a
> tendency to rock forward possibly tearing itself away from the sound board
> from the collective forces.  Combining Yankee ingenuity and "Scotch
> determination" he pursued the only other alternative, and drilled the
> other half in oposite direction and install them alternating. Indeed
> looking at the marks on the bridge under the agraffes, some are indented
> toward the tuning pins, some have an indentation  toward the bridge pins.
>
> Richard Moody

My guess is that by the time they finally got it pretty much "right" the bad press
from earlier efforts had pretty much doomed the feature.

Richard, on a related subject -- did you notice the crown of this soundboard?  Was
it crowned up or down?  I'm sure that at least one of the Hallet & Davis pianos
I've encountered was built with a "reverse" crown.  The strings pulled up against
the agraffes.

Regards,

Del