[CAUT] Harpsichord questions (long)

[Fred Sturm]

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Comments (answers) interspersed below:
On 4/17/05 2:41 PM, "David Vanderhoofven" <david@vanderpiano.com> wrote:

> Easing the keys seems rather crude.  The key pins are much smaller diamet=
er
> than in a piano.  There is a mortice for the key pin to move forward and =
back
> in, but there are no keybushings.  The front key pin is located at
> approximately the balance point of the key, and the back key pin is locat=
ed
> close to where the capstan would go in a piano key.  With the keys and
> keyframe out, we played each key a few times to find the sluggish keys.  =
When
> we found a sluggish key, we took the key off the keyframe and inserted a =
spare
> key pin into the mortice and moved it back and forth until the key was no
> longer sluggish.=20
>=20
> I suggested to the professor about polishing the keypins and lubricating =
the
> keypins, and he was hesitant, wondering if the polish or lubricant would
> contaminate the keys.  I was thinking of using Flitz or Simichrome polish=
 and
> the cleaning the key pins well, then applying McLube or a teflon spray to=
 the
> key pins.  Or perhaps applying a little bit of micro-fine teflon powder o=
n the
> keypins? =20
>=20
> Question #1. Have any of you noticed any ill effects from
> polishing/lubricating harpsichord keypins?  Is any lubrication necessary =
or
> even helpful on harpsichord keypins?
Haven=B9t had any ill effects, nor would I expect any. I doubt polishing and
lubing will cure all the sluggishness problems, but it will at least preven=
t
squeaking (which does arise sometimes).
>=20
> Question #2.  How can you tell if the key pin is tight at the top or the
> bottom of the key?
You=B9ve hit on the basic problem of easing harpsichord keys. The mortise is
parallel to and in contact with the pin from hole to the top. It is very
difficult to tell where the friction is. My best advice is to use a
jeweler=B9s file =AD the one with parallel cutting surfaces that comes to a
point =AD to clean out any loose wood fibers within the mortise. Usually that
is the problem. Take care not to make the mortise =B3tapered=B2 (keep it
parallel to the pin, and don=B9t over-ease). A wee bit at a time. Try to make
most of the pressure on the file =B3at the point=B2 - IOW picture yourself
cutting away wood below the top of the mortise, not touching the top of the
mortise or enlarging the BR hole.
    The mortise is typically created by drilling one hole all the way
through (creating the balance hole), with a couple other holes drilled on
either side but not all the way through the key. Then a metal punch of
appropriate shape and dimension is hammered into the hole to create the
requisite shape. Leaving plenty of residue to cause problems.
    Another useful =B3easing=B2 tool is the correct sized drill bit (preferably
selected from a set of 1 =AD 60 numbered bits, but you might find the right
size in metric or SAE) - it needs to be just a couple thousandths larger
than the pin. Use it in a pin vise, turning it while angling it back and
forth within the mortise - carefully.
    Bottom line: mortises must fit the pins very closely, but be free. Very
troublesome design. Use care when easing. Keys should have minimum lead in
them for return (leads are almost always on the back side), and the key
should just float to rest position. That=B9s the ideal =AD you may find you hav=
e
=B3over-leaded=B2 keys. But it is easier to determine if the key is eased
=B3perfectly=B2 on a harpsichord than on a grand piano (that=B9s the =B3good=B2 news
<g>).
>=20
> Question #3.  Can I use regular paper and card punchings to level keys in=
 a
> harpsichord, or do I need to buy some special smaller punchings for this
> purpose?
Paper and card punchings for piano work just fine.
>=20
> Question #4.  Is it possible to do fine adjustment of key dip on a
> harpsichord, and how is this done?  Or should I even worry about this on =
a
> harpsichord?
Harpsichord key dip should be reasonably/roughly even, but it isn=B9t the
issue it is with a grand piano. Some have the upstop rail you describe.
Others rely on the jack hitting the jack rail =AD in which case one trims the
top of the jack to arrive at the appropriate dip. In general, if it works,
leave it alone.
>=20
> The harpsichord will be used as part of the continuo for the Vivaldi Conc=
erto
> in C major for Two Trumpets & Orchestra, R. 537.
>=20
> Question #5.  What would be an appropriate temperament to use for a
> harpsichord with this music?
Mr. Young=B9s temperament is my favorite generic well-temperament for baroque=
.
Valotti or Valotti/Young are a couple other reasonable choices. But you
might actually be best with old vanilla ET depending on the orchestra. In
the final analysis, it is unlikely anyone (except possibly the
harpsichordist) will notice.
> Thank you all for this wonderful list and your help!
>=20
> David Vanderhoofven
>=20
>=20
Regards,
Fred Sturm
University of New Mexico





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