Cracked plate

[Delwin D Fandrich]

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  ----- Original Message -----=20
  From: Todd Mapes=20
  To: pianotech@ptg.org=20
  Sent: December 13, 2001 5:13 AM
  Subject: Cracked plate


  List,

  This week I experienced my first cracked plate.  It's not an =
experience I would like to have again.  The piano was a Kimball console =
which, according to the customer, had not been tuned in 18 years by the =
previous owner.  The current owners had recently acquired it for $300 =
and wanted it tuned up so the wife could play Christmas music.  I opened =
the piano up and found a dead mouse and several mouse droppings (the =
mouse was mostly decayed), which, in my opinion shows that the piano =
hadn't been tuned recently and probably not played in several years, =
either.  I noticed no other problems besides a few broken Schwander butt =
springs, so I got out my SAT III and checked the pitch.  The piano was =
185-200 cents flat.  I did the first pitch raise with no overshoot and =
then checked pitch again.  The SAT III reading now was about 35-40 cents =
flat, so I programmed in a 25% overshoot and began tuning the piano at =
A0.  As I crossed the bass/tenor break, I heard a LOUD "bang" which was =
much louder than any string breakage I'd ever heard, so, fearing the =
worst, I got down under the keybed and looked at the plate.  The plate =
had cracked right through the hitch pin area.  The crack was all the way =
through the plate and I called the customer over and informed her of the =
plate breakage and that it was probably not feasible to repair the =
plate, and even if it was, there could be no guarantees of success on =
such a repair.  She understood that the piano was a complete loss, I =
collected a minimum service call fee and left.

  Two days later, her husband calls me up demanding that I reimburse him =
for $300 or provide him with an acceptable replacement.  I informed him =
that I had no intention of doing so, because the plate cracked due to =
lack of structural integrity.  He informed me that his opinion was that =
the plate cracked due to my incompetence and/or negligence.  I then =
explained the pitch raise procedure that I performed and told him that =
to the best of my knowledge, I had exercised due professional care and =
was not responsible for the demise of his piano.  As a parting comment, =
the customer said he would just have to take me to small claims court =
and recover his money.  He could be bluffing, but then again, he seemed =
pretty adamant about collecting his $300.

First, was the breakage your responsibility? Unlikely. Speaking from =
experience it is not all that unusual for plates on pianos of this type =
to break on their initial chip to pitch--which is roughly the equivalent =
of what you were doing. I mean it isn't something that happens every =
day, but it's not all that unusual an event, either. Plates of this type =
were typically designed and engineered with a minimal safety margin. =
Indeed, it may not have been 'engineered' at all in that sense. More =
likely the stress analysis consisted of "If at least a few of them don't =
break once in a while we're probably putting too much iron in =
there--take out the excess and lower the cost." In other words, if the =
majority of them don't break, they're strong enough.

Can it be repaired? Probably. From your description of the location of =
the break it doesn't sound like it was an area of all that much stress. =
It's a bit late now, but you might have looked for an improperly seated =
plate or nosebolt in the vicinity. In any case, it can probably be =
either stitched or welded. Personally, I'd opt for welding--I've had =
more experience with it. And, you'd probably want a bit of reinforcement =
added on for good measure. I've been involved in the repair of quite a =
few cracked and/or broken plates by now and, to the best of my =
knowledge, they are all holding fine. (I'm not a welder, but I've known =
some really good ones over the years.) I've also declined even =
attempting to repair a few, such as the crack-prone Bechstein plates of =
some decades back. Apparently a combination of poor metallurgy, overly =
rapid cooling and generally poor design. The Kimball plate in question =
was cast by either Kelly or Wickham. In either case the tensile strength =
would be up around 24,000 to 26,000 lbs/in2 minimum. In other words, the =
carbon content should be low enough that a welder familiar with modern =
welding techniques and materials and with cast iron Diesel engine blocks =
and heads shouldn't have any problem with it.

Would it be worth the effort? Probably not. No, make that definitely =
not. The plate would have to come out of the piano, which means =
restringing and all of the attendant work. The cost of welding, strings =
and pins just exceeded the value of the piano. Not to mention your labor =
and moving costs.

You might want to go back to the recent Journal article on broken plates =
and read up on the information presented there. After you are some more =
conversant on the subject, call the owner back and see if you can get =
him to see the futility of his position. (But, try to understand his, as =
well.) In the end you will probably prevail in court, but it will cost =
you a lot of time in preparation and most of a day for the actual event. =


Good luck.

Del

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