Capo Hardening, was: Tuning problems under capo bar

[Sarah Fox]

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Oops...  My email was delayed, due to an internet problem.  My question =
about grinding the capo had already been answered.  However, what about =
the magnetic hardening?  This is usually done with higher tech alloys, =
not gray cast iron.  But can it be done with cast iron??? =20

Regarding the prospect of setting a steel rod in a groove ground in the =
capo...  What dia of rod?  Also, is spring steel the best choice -- i.e. =
like piano wire?

Peace,
Sarah
  ----- Original Message -----=20
  From: Sarah Fox=20
  To: Pianotech=20
  Sent: Saturday, January 25, 2003 1:27 AM
  Subject: Re: Capo Hardening, was: Tuning problems under capo bar


  I've wondered about this myself.  My Wissner's capo is very badly =
grooved.  I've shifted some of the strings slightly to eliminate their =
"zinging," but the capo will obviously need reshaping.

  As far as I'm aware, different metals are hardened via different =
methods.  However, the fact remains that this usually involves heating =
and cooling for various periods of time -- something that's hard to do =
with something as large as a harp -- and difficult to do without =
stressing the metal and risking a crack.

  I believe some ferrous alloys are hardened with magnetic fields, =
perhaps with moderate heating.  Perhaps this could be a useful =
alternative?  I have no idea how this is done, though.

  Alternatively, does anybody ever grind the original capo off and =
overlay a hardened bar, fitted for height?  It could be epoxied in place =
for a tight mechanical contact.  Of course this begs the question of =
what happens when a capo is ground and filed and ground and filed and =
ground and files -- until the downbearing is inadequate.  Yes, I know =
the plate can be lowered, the bridge can be built up, the aliquot plates =
can be filed, etc., but does this ever present a problem, such that a =
technician might decide to rebuild a capo?

  Peace,
  Sarah Fox=20
  (Columbus, Ohio)
    ----- Original Message -----=20
    From: Kevin E. Ramsey=20
    To: Pianotech=20
    Sent: Friday, January 24, 2003 8:27 PM
    Subject: Re: Capo Hardening, was: Tuning problems under capo bar


    Hello Ron. I there anything you can tell us about hardening the =
capo. I've seen you write about that before. Is this something you do in =
your shop? Do you do it to all pianos? Do you have a method of testing =
the hardness of the capo? Am I asking questions that have already been =
answered? Thanks.=20

    Terry Farrell=20

        Terry, I don't know about Ron, but I've thought about it, and I =
don't see how you could harden the capo. I hope I'm wrong, but you hard, =
or temper a metal by heating it until it glows for a certain amount of =
time, and then you quench it in either oil or water. The plate is going =
to act as a gigantic heat sink, not allowing the metal to get to the =
proper temp, and you'd have trouble quenching it even if you did. When =
you heat a metal and allow it to cool by itself, it's called annealing, =
and it softens the metal. Others can tell me if I'm all wet, but that's =
how I understand it.=20

        Kevin E. Ramsey

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