MH BB Pinblock

[A440A at aol.com]

I wrote: 
 >The sound transmission is also noticeably 

  different if you tap the undowelled block then clamp it to the stretcher 
and tap it  again.  

Ron writes: 


>>It also is when you tap the undowelled block, and the same 

block with just a clamp attached without the stretcher because 

you've lowered the resonant frequency and raised the impedance 

of the thing with the mass of the clamp. >>

Judging on the immediate evidence ( a freshly fitted block in the shop), that 
is not true.  The simple added mass of the clamp on just the block doesn't 
create anything at all like the audible difference when that clamp connects the 
stretcher and the block. 

>>A dial indicator, set up 

under the stretcher and pinblock (plate firmly screwed to it) 

will tell you pretty easily. How much deflection with your 

weight on just the stretcher, and your weight on just the 

plate/block assembly? I think you'll find the stretcher to be 

considerably, possibly profoundly less rigid.<< 

   I don't think that addresses the topic.  What I thought was being 
discussed was the change made by connecting the block and stetcher, not comparing them 
with each other as stand alone components. If you measure the deflection of 
the plate/block clamped in the piano, and then  measure what happens when the 
stretcher is firmly fixed to the block, I submit there will be a measurable 
difference in rigidity.  
 
     I am going to measure what a weight will do on the plate block and then, 
after I finish the doweling, I will measure it again.  I am going to make a 
guess that there will be a measurable difference.  I also don't know if the 
deflection by weight actually provides any measure of the sound transmission 
qualities of the structure, (which is the reason I dowel the stretcher)
regards, 
 
Ed Foote RPT 
http://www.uk-piano.org/edfoote/index.html
www.uk-piano.org/edfoote/well_tempered_piano.html
 <BR><BR><BR>**************<BR>Looking for a car that's sporty, fun and fits 
in your budget? Read reviews on AOL Autos.<BR>      
(http://autos.aol.com/cars-BMW-128-2008/expert-review?ncid=aolaut00050000000017 )</HTML>