Pinblock/Frame Separation

[Bdshull@AOL.COM]

Hi, Keith:

I believed that more of the string line/vbar was moving than Terry indicated 
(I could be wrong).  My thinking was that the plate was bending more 
gradually, extending further down.  I'm trying to remember the Hamilton plate 
- if there is not a lot of vertical strut-like or "cupola/flange" design in 
that area, then you are right, most of the bend could be at the pressure bar. 
 My recent, personal point of reference was an Alcoa Aluminum Special, with 
more strut work;  the dampers had stopped lifting.....

The plate will be in a stressed position until it is pulled back into the 
original location,  But the downbearing may not be affected as much as I 
thought based on the scenario presented.  I have seen broken Hamilton plates, 
but not from back separation (not yet).  And if the pivot is at the bottom of 
the pinblock, there may still be a slight margin of downbearing loss.  

Where I am coming from is that more of these separated backs can be pulled 
back together if we give the repair enough time.  If closing the gap is 
desirable (certainly we all would agree on that), why not close the gap?  

Thanks, Keith.

Bill Shull, RPT


In a message dated 7/26/00 4:33:56 PM Pacific Daylight Time, kam544@flash.net 
writes:

<< Since you have chosen to support Newton's comment, would you, or Newton,
 care to explain how downbearing will be affected if the gap is not
 completely closed, yet made completely stable with the repair suggestion I
 gave.
 
 Please keep in mind the original post indicated:
 "...If you draw a line from the pressure bar in the high treble, extending 
out
 to the edge of the plate, this is where most of the bend occurrs (at the
 base of the pinblock)..."
 
 Keith McGavern
 Registered Piano Technician
 Oklahoma Chapter 731
 Piano Technicians Guild
 USA >>