Plate Hitch Pins

[Newton Hunt]

Hello, All,

With all this confused "information" flying around about plates and hitch
pins I though I would have a conversation with Bob Beck who spent
weeks in the Wickum foundry working out details on Kimball grand and
upright plates.

All hitch pins, except those at the upper hitch rail on uprights are drilled
perpendicularly to the plate surface.

Hitch pins are made of mild steel, just like common nails, are about 5/8
inches long, are pounded in by pneumatic drivers to half their length,
then bent over.  The pins are rounded at both ends for easy driving and
for appearance.

The fit of the pin and its size, .156", is critical but considering the incon-
sistency of cast iron and the fact that the surface metal is different than
the inside metal (crystallization caused by different cooling rates) can
cause problems.  Plates do crack during pinning and some rare pins are a
bit too loose.

The pins are lacquered to provide a minor amount of lubrication and to
prevent them from rusting while hanging around until painted.

There were efforts to cast hitch pins in place when the plate was cast, but
that did not work as well as hoped for because of breakage and replace-
ment difficulties.

Some pins are plated and installed after the finish of the plate, which has
its own problems with chipped finishes and other minor details.

It is difficult, and very expensive because of the time involved, to drill
holes at angles to surfaces.  Try it yourself sometime and you'll see why
holes are drilled at 90 degrees to a surface.  Wickum is the only plate
maker in the US and he does all the plates of all the pianos made for this
cotenant, with some notable exceptions.  Consider the number of holes to
be drilled per day!

Robert Beck, (201) 884-0404, has presented local and national lectures
and demonstrations of plate casting and finishing procedures.  A most
interesting and informative class.

So, I stand by my earlier post about replacing and installing new hitch
pins with a properly drilled hole and a nail of the right size.

Have a nicely hitched day.

    Newton
    nhunt@rci.rutgers.edu