[pianotech] -Action ratio class for the institute

[Dale Erwin]

 My offering of class material to the institute. I'll be doing this in Feb at West Pac in S.F.

 

Dale S. Erwin
www.Erwinspiano.com
209-577-8397

 








               Understanding  Action   Ratios and Hammer weights





                                    by   Dale Erwin, R.P.T.




  Aspiano  technicians we cannot confidently   guarantee a successful action rebuild without understanding that action ratios & key leverages are key to our success. Discovering the effects of action ratios reveals that an arbitrary installation of hammers is a guessing game! Which... usually results in a heavy action, poor regulation,& excessive leading etc. As we learn to control these ratios we gain mastery over the action rebuilding process. The result produces beautiful touch and musical sound.



  A simplified definition of an action ratio is how far does the hammer rise per unit of key movement. For example...
   1 mm of key movement produces 5 mm of hammer movement...this equals a 5 to 1 ratio and so on.
  Any ratio above 6 to 1 fitted with a too heavy hammer will always produce a heavy action and unhappy clients

 








   Action ratio   information allows us to:
  1. Choose correctly dimensioned parts that correct poor leverages and enhance action performance
  2. determine regulation parameters
  3. Select replacement hammers for a specific hammer   weight 
  4. Prepare a specific hammer weight curve for chosen leverages
  5.   Choose a reasonable balance weight removing excessive key leading
  6. Decide when to move the capstan, and when new keys are in order 
  Using the "Erwin action ratio gauge", we will determine an action/key ratio in about 5 minutes on typical action and use it to guide the job through steps 1 thru 5 using mocked up parts.
  Other related   subjects presented: Graphs,tools & visuals will show how to   prepare a set of hammers for a smooth strike weight curve. Learn what is meant by Hammer sampling? and why it is important.

 

  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  



  
  
  
  
    
  
   
    

















 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 


 
 
 


 
 




-- 
Ryan Sowers, RPT
Puget Sound Chapter
Olympia, WA
www.pianova.net

 
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