[pianotech] Key dip to blow ratio

[Nick Gravagne]

Lee,

 

I concur with Jerry. The 9.2mm of key end travel come from the 47 - 1 = 46;
and 46 / 5 = 9.2mm. Then 10.5 - 9.2 = 1.3mm

 

Better not to think of the 52.5 as blow distance. The 52.5mm represents the
total "hammer rise" relative to dip and action ratio. If you were to remove
the let-off button you would see the hammer rise to its full extent.

 

Regards

 

 

Nick Gravagne, RPT

Piano Technicians Guild

Member Society Manufacturing Engineers

Voice Mail 928-476-4143

 

  _____  

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Jerry Cohen
Sent: Tuesday, March 10, 2009 12:23 PM
To: pianotech at ptg.org
Subject: Re: [pianotech] Key dip to blow ratio

 

Lee,

 

I think you mean 52.5mm, not 55mm blow (5 X 10.5 = 52.5).

 

However, there is also after touch within the dip. For example: suppose blow
is 47mm and let-off is 1mm. Then the hammer will rise 46mm for 9.2mm of dip,
which leaves 1.3mm dip for after touch.

 

Jerry Cohen, RPT

NJ Chapter

 

  _____  

 

A hammer blow / Key dip ratio of 5:1 would result in a 55mm blow for a 10.5
key dip. 

Would this not be an excessive blow distance?

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