marking location of rear string bearings

[Michael Spreeman]

Barbara,
 
There are 3 basic approaches to rebuilding:  
 
1.  assume the factory knew what they were doing and duplicate exactly what they did.
2.  assume nothing was done correctly at the factory and do everything in your power to return things to true spec.
3.  examine what was done at the factory and implement modifications and improvements to your, or the customers tastes.
 
With the approach of #1, the placement of the aliquots can be measured from rear bridge pins.  This measurement is then used to position the aliquots front to back. Left to right placement is fairly easy during the stringing process.
 
Another approach is to make a pattern of sorts. A piece of mylar or paper (paper can change dimensionally, so it's not the best choice) can be cut to fit the section you are marking and laid on top  of the bridge pins.  The pattern is sanded to expose the tops of the bridge pins and the aliquot location can me marked on the pattern with a pen or fine tipped magic marker.
 
With approach #2, the aliquot location can be measured and compared to the speaking length of the unison it goes with.  Determine the ratio of the two to see how the speaking length of the duplex length relates to the primary speaking length in order to see if they were put in the right place during construction (or after someone else rebuilt it).  Corrections then can be documented on your pattern.
 
With approach #3,  you have the opportunity to change the duplex scaling (providing you even want a duplex scale, as some prefer them and some do not).
 
If you have already removed the aliquots without marking them, this may be the only approach.  
 
I find that by using measurements, the aliquots can be easily positioned one at a time during the stringing process.  
 
On the other hand, the pattern system allows one to temporarily locate place all of the aliquots to the plate prior to stringing with a drop of super glue.  I've found that the aliquots have a tendency to break loose when stringing with this system and have abandoned it for this reason.
 
And, yes, tape would work fine too if you are not refinishing the plate :).
 
All the best,
Michael
                Michael C. Spreeman http://www.spreemanpianoinnovations.com


From: piano57 at insightbb.comTo: pianotech at ptg.orgSubject: marking location of rear string bearingsDate: Sat, 26 May 2007 12:56:38 -0500



Howdy,
 
I'm doing some work here that I haven't done for about 20 years.  I'm an action girl, but agreed in a weak moment to restring and fix up a friend's piano.  (That's all I'm going to say about it, it's a ridiculous story how it came about.)
 
Anyway, I plan on doing some cosmetic fixing up of the plate, and was wondering how I should mark the location of the rear bearing gizmos.  My thought was to use some tape.  Is that what folks do?
 
Thanks,
 
Barbara Richmond, RPT
near Peoria, IL
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