action ratios

[Stéphane Collin]

Hello Richard.

Thanks for interest.

Here are my measurings on my latest Bechstein model B (2 m).

5 mm dip gives an average 25.5 mm hammer rise (linear, not angular, but anyway I couldn't achieve a precision measuring so this matters).  I assume this is a 5.1 ratio action.

Sorry for WW and FW, but this piano is in very last stage of rebuilding, and waiting for customers, so I'm not about to pull the stack out of it now.

But I measured KR through length between balance point and front key, just above the front pin (243 mm) and length between balance point and whippen center for the rocker leg (no capstan on older Bechstein) (140 mm).  This should give us a KR of 140/243 = 0.576

Here are the other measurements

note   DW    UW    SW
C-3   60      40       8.4
C-2   60      39       8.4
C-1   63      47       8.9
C0     62      39       8.3
C1     57      36       7.3
C2     56      35       6.5
C3      56     32       5.8

What do you think ?

Greetings, and much respect.

Stéphane Collin.


 
----- Original Message ----- 
From: "Richard Brekne" <Richard.Brekne@grieg.uib.no>
To: "Pianotech" <pianotech@ptg.org>
Sent: Friday, November 01, 2002 10:43 PM
Subject: Re: action ratios


| Hi Stéphane
| 
| More parts of the puzzle to think about eh ? And this question was a fun one for sure. To be honest I havent really thought about exactly this question before.
| 
| Perhaps if you sample some of our now standard parameters we might be able to see into how this may or may not fit into this whole question of  ratio and hammer mass.
| 
| If you could give us the SW's, FW's WW's, KR, UW, and DW on say 10 sample keys we might have some fun with this one. And if you also could measure how far the hammer travels for 5 mm key travel (be very very accurate) that would be nice as well.
| 
| I'm not so sure I'd buy into this being a voicing problem right off. I mean if the extremes are so very good then I have a hard time understanding that the hammers elasticity is involved. But I will ponder what others say with interest.
| 
| Cheers
| 
| RicB
| 
| Stéphane Collin wrote:
| 
| > Hi Richard, David, Bill, etc.
| >
| > I've been following the thread with much interest.
| > May I ask an innocent but pragmatic question (I think related to this topic) ?
| > More than often, I encounter this problem when rebuilding Bechstein pianos : I get the sound right, I get the touch feel ok, but the whole instrument always happens to be difficult to control, as the dynamic output switches too quickly from PP to mF (I mean :  the dynamic shades are not progressive enough.  Very soft playing is fantastic, very loud also, but progressively crossing from soft to loud happens to be difficult to control, as sound gets loud too quickly, which is musically not desirable at all).
| > How would you all cure this problem ?
| >
| > Thanks to all for great expertise.
| >
| > Stéphane Collin.
| >
| 
| --
| Richard Brekne
| RPT, N.P.T.F.
| UiB, Bergen, Norway
| mailto:rbrekne@broadpark.no
| http://home.broadpark.no/~rbrekne/ricmain.html
| 
| 
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