[pianotech] privately

[David Love]

Do you mean by single measurements, single methods of measuring or the measuring of single keys?  

 

I know that you survey many samples in your own system of measuring weight in order to determine an average and I think that is wise for those using that system.  Even the most careful measuring leaves some things open to interpretation: at what weight does the key actually start down, and similarly for determining the upweight.  So I’ve also found it necessary to take multiple measurements when using weight systems to establish the action ratios but overall I don’t find it reliable and get numbers with quite a disbursement.   With distance formulas as I’ve described I don’t find that so many samples are necessary and the results are more reliable.  Sharps and naturals, of course, can vary in the key ratio, but wippen and shank levers tend to be uniform.  

 

If you mean that one should employ multiple systems, then I tend to agree.  I use distance formulas to establish the action ratio and then verify my weight predictions by setting samples on several notes.  I don’t see much reason for using multiple distance formula measuring systems, but I don’t guess you meant that.  

 

David Love

www.davidlovepianos.com

 

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf Of David C. Stanwood
Sent: Thursday, January 17, 2013 5:46 AM
To: pianotech at ptg.org
Subject: Re: [pianotech] privately

 

HI David,

 

I'll weigh in by saying that I don't put much confidence in single measurements to draw statistical conclusions from measured data.   Averaging multiple measurements will give a more certain picture of what is real.   As for distance ratio I prefer to rely on direct measurement methods...  When comparing weight to distance I measure to the same point 13mm in from the front of the top of the key for both types of measures.

 

David S 

 

 

-----Original Message-----                


 

>From: David Love <davidlovepianos at comcast.net>

>To: pianotech <pianotech at ptg.org>

>Sent: Tue, Jan 15, 2013 5:56 pm

>Subject: [pianotech] Measuring Action Ratios

 

>When analyzing actions I've used both the gauge for measuring key travel

>versus hammer travel as well as the actual measuring and multiplying out the

>three separate lever arms.  So far, they've been fairly close.  However,

>today I was measuring a MH A and the gauge gave me a AR of 5.2 whereas the

>measuring of the three arms gave me 5.9.  Curious.  Assuming I'd measured

>incorrectly I remeasured several times and got the same result.  When using

>the numbers to calculate via the Stanwood method the predicted balance

>weight/front weight/strike weight relationships the 5.9 was clearly the more

>accurate number.  At a bit of a loss to explain it so, for the moment, all I

>can do is report it.   

 


>David Love

 

	

 

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