I too have had problems years ago with the major piano suppliers failing
to drill hammers with the proper pitch angle.  They always came back
straight.

That was about 30 years ago, now, because I drill them myself today.
But I called both Schaff and American and told them that the samples
I had sent them were drilled with pitch, and the new hammers I received
had been drilled straight.  I was told by both companies that they
didn't drill any hammers with pitch angle.  I assume they still do not.

Their drill setup apparently did not allow for pitch angle.  One upright
I know of has pitch only in the bass section and straight-drilled in the
treble, like Tonk pianos.  A very few other actions only drilled pitch
in the treble, and sometimes shaved the high treble shanks to enhance
the torque effect.  Most upright actions drilled pitch throughout,
however.  They are almost without exception, all pitched.

Many rebuilders of today just use straight-drilled hammerheads and
ignore the pitch angle.  Whatever they are sent by the supplier goes on.
This "works" but not as well because the center of percussion raises
above the striking line on hard strikes, weakening the blow.  Doing just
the opposite that was intended by the artist.  When hammers are drilled
with pitch, it is easy to hear the difference in dynamic range.

The theory is, on normal and soft notes, the hammer should be mounted
fractionally below the ideal strike line, and in addition, the hammer's
own center of percussion should be a little below the strike line too
(caused by the pitch angle).  This combination weakens the strike
noticeably and proportionally on soft to normal playing.  But when
adding accents, the hammer shank flexes more and more, just like a golf
club shank, raising the center of percussion and the hammer's ideal
strike point.  So when the hammer hits the string at a right angle to
it, and precisely at its most efficient point besides, you get all that
you purchased at the key -- full power.  A striking difference.

I understand that some technicians don't appreciate the effect nor care
to learn, in the same way that many people (even "musicians") are
satisfied with a small console piano, for whom good dynamic range is a
moot point because they play at a pp-mf salon level.  There are people
who appreciate and delight in the power differences, and others who
could care less, and don't even notice the dramatic differences.

When Cristofori built his first piano, the thing that most amazed people
about it was the wonderful ability to express powerful emotions, so they
named it a "Soft-Loud" [Piano-Forte].  Once we know the history and the
purpose, it's up to us to maintain it whether generally appreciated or
not.

We should not be the generation satisfied with the "Tinkletone Piano-
Mezzoforte."

Craig Brougher