Pin blocks

[John Gunderson]

I was recently called to check a piano in a local restaurant with a
tuning stability problem.  It is an Otto Altenburg grand, manufactured
by Samick.  It is 13 years old and has had this tuning problem since it
was new.  The stability problem is in the 5th, 6th, and 7th octaves.
Those notes go out of tune almost imediately after it has been tuned in
spite of the fact that the piano gets tuned every three weeks year round
(For the record, I am not the tuner).

When I examined the piano, I removed the action and place a
straight-edge against the bottom to the pin block.  In the 1st through
4th octave region the straight-edge laid flush across the bottom of the
pin block but in the 5th through 7th octave range the pin block buldged
out at the bottom and the straight-edge would not lay flush, it rocked.
My conclusion was that the pin block is delaminated in that region and
that is the cause of the tuning instability.

I post this message because over the years I have observed this very
same condition (pin block buldge) and problem (tuning instability in
that region) in at least two other Samick-built Altenburgs and one
Hyundai Maeari grand (also Samick-built).  All these pianos were new or
near-new.  I would not expect any of them to be having tuning stability
problems due to age or abused.  All the pianos were built in the early
to mid 1980's.  The only reasonable explanation that I have is that the
pin blocks were damaged during stringing.  The pin block was not
properly supported underneath while the pins were being driven in.

Does anyone have any insight into this message?  How are pianos strung
in a factory such as Samick's?  Is it automated or done by hand?  Is it
possible that a pin block could have buldges on the bottom and not be
damaged?   Any input will be appreciated.   Thanks

John Gunderson,  Member, North Jersey Chapter