Pin Block Delamination

Jon Page jpage@capecod.net
Sun, 22 Nov 1998 12:17:38 -0500


List,
MMDers will know of John Tuttle's question on pin block
delamination. Over the course of the past few days we have
been discussing the matter and I suggested to inquire on
this list. I thought he was subscribed. Anyway, here is the ? . . .
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Hi All, 
I need a general concensus from the group of professional 
piano rebuilders. Here's the situation:

I was called in to evaluate the condition of an Aeolian 
Duo-Art grand that was 'completely restored' three years 
ago. Upon looking at the unit, my immediate response was, 
'this unit was not restored, it was repaired and some 
rebuilding work was done'.

The unit was restrung, new hammer heads, dampers, key tops, 
repaired soundboard, retubed, all pneumatics recovered and 
piano refinished (if you can call it that, the pores are 
plainly visible). 

Upon removing the key slip and boards covering the player 
assembly, I immediately noticed two very large separations 
in the plys of the ORIGINAL PIN BLOCK in the sub-bass 
region. I could clearly see the tuning pins through the 
separations. The larger separation, between the third from 
the bottom ply and the second from the bottom ply, is a full 
1/8" wide and about 2-1/2 long. The second separation, from 
the next to last ply and the bottom ply, is 3/32" wide and 
about 1-3/4" long. The separated plys are also cracked in 
half at the mid-point, directly in line with one of the 
tuning pins. Laying a straight edge across the tops of the 
tuning pins, they were found to all be the same height.

A simple drawing of the problem area can be seen at:

http://www.player-care.com/gifs/splitbl2.gif 

The home in which the unit resides has 24/7 humidity control 
and central air-conditioning, i.e., a controlled environment.

My questions to all of you are: 

1) Is there any way this degree of separation could have 
occurred AFTER the unit was restrung three years ago?

2) Does anybody have any examples of a block delaminating 
to this degree under any circumstance except improper 
stringing practices?

Thank-you, 

John A. Tuttle (john@player-care.com)
 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
first published in the Mechanical Music Digest:   http://mmd.foxtail.com/ 
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

I gave John instructions on how to subscribe to this list's digest but
just in case please cc to him also, this could be a good thread.



Jon Page
Harwich Port, Cape Cod, Mass. (jpage@capecod.net)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


This PTG archive page provided courtesy of Moy Piano Service, LLC