[pianotech] Action Ratio Measuring redux

[Dale Erwin]

Hi David
  This is not wasted time. This is how we learn things. It is obvious that no matter how you average it the ratio is high. The measurements don't need to be microscopically accurate to tell you what to do of course. ie 6.1-6.3. Dosen't matter that much at thsi stage of analysis. Just put on a 17mm shank and hammer, pull out a capstan and use a capstan boat and move it around till an action ratio closer to your choice comes into view.
Dale



Dale Erwin R.P.T.
Erwin's Piano Restoration Inc.
 Mason & Hamlin/Steinway/U.S. pianos
www.Erwinspiano.com
Phone: 209-577-8397

 
  





-----Original Message-----
From: Brown, David <dcbrown at mail.smu.edu>
To: pianotech <pianotech at ptg.org>
Sent: Fri, Sep 28, 2012 4:41 am
Subject: [pianotech] Action Ratio Measuring redux


All-

Sent this yesterday with attached photos, but no luck. Here is the message-

Well , here are results from a new Renner action model. After measuring the 
action parts themselves , I ended up with several different possible 
combinations depending on which measurements I used. So…… I figured, let's see 
what displacement gives me, and then which combinations of numbers roughly equal 
what I got with displacement. I include some photos of that set up. Not the 
actual measuring, just an idea of what the set up looked like. Ed Foote's idea 
of a needle in the hammer worked very well. I got 37 mm of hammer travel for 
5.875 mm of dip giving me a ratio of 6.297, or 6.3. Using  combinations of 
action measurements, the closest I could come was either 6.49 or 6.10 , right on 
either side of the displacement, but still not close enough.Add them up and 
divide by two gives me 6.3., but that seemed like fudging.

Entirely too much time spent on this today, but very informative. I will 
continue this on a B action scheduled for a new keyset and parts at the end of 
this semester.Big thanks to all who shared and helped.

Best-

David

David C. Brown RPT
Piano Technician
Division of Music
Meadows School of the Arts
Southern Methodist University
Dallas Texas 1-214-768-3976



 
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