Is that plate broken?

Delwin D Fandrich pianobuilders@olynet.com
Sat, 27 Sep 1997 07:26:53 -0700


Danny Moore wrote:

> ...There was very little
> damage evident UNTIL I pulled the plate.  The mass of the plate caused
> the plate to continue on its travel even after the case came to a rather
> sudden stop.  All the plate bolts were pulled out about 1/4 of an inch -
> nose bolts - everything.  It was not noticable with the plate strung and
> in the case.  There was no evidence of any damage to the plate, however.
> 
> I would think that structural damage in the rim area and where the pin
> block was doweled to the case would be a much greater likelyhood than
> plate damage.  After all, the plate was rather well protected by the
> mass of wood it was bolted to.
> 
> It will be interesting to read other comments on this subject.
> 
> Good luck.
> 
> Danny Moore
> Houston Chapter
-----------------

Danny,

If memory serves, Howard's were built with select poplar rims--not
exactly the most robust of woods. Did they not also use relatively small
wood screws? Either way, if the piano had been afflicted with the plate
bolt tightening regimen, they might not have been holding much before
the great fall.

Most of the plates that have come through my shop actually damaged—i.e.,
cracked or broken—due to falls of this type have had the top two or
three struts cracked just aft of the capo ‘d astro bar. This is already
one of the weakest areas of the plate. There is already quite a lot of
stress at the transition between the relatively thin strut and the
relatively massive capo ‘d astro bar due to the uneven cooling rates
between the two areas.

Your analysis of magnafluxing was both interesting and practical.
Thanks.

—ddf



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