New Scale/Scale Stick

[Ric Brekne]

Hi Joe

Thanks. Let me see if I understand you right. You are saying to compare 
the old scale lengths with the new, determine the ratio of the 
difference between each, and offset the hammers accordingly ? I suppose 
one takes the existing strike point on the strings and duplicate that in 
terms of the ratio of the string length to striking point on the new 
strings ?

Looks to me like the most significant change will be in the higher 
treble. I'm looking at two alternatives before placing and notching the 
new bridge.  The top string A85 was 48 mm long.  A very short scale to 
say the least. One scenario has that going to 54 mm and the lowest bass 
string increasing 3 mm in length so as to make possible as smooth a 
transition from the longer (new) high treble to the tenor section.  The 
other is a much more moderate change keeping the tenor and most of the 
treble lengths the same, but increasing the top octave lengths a 
little... with A85 going up to 50.5.  In both cases tho it would seem to 
me that any change in striking point would be most significant in the 
high treble... yes ?

The former of these two alternatives was designed by a fellow who uses a 
completely different scale program then I've seen before. It uses a 
parameter called "Harmonicity" (as opposed to inharmonicity). As I 
understand it is a parameter that uses an idealized inharmonicity curve 
as a base line and graphs how far off this idealized line the scales 
actual inharmonicity is.  The idealized inharmonicity is based on the 
scale length as a whole in some fashion I couldnt quite discern.  I'd be 
curious to hear thoughts or of others experiences with this parameter in 
scaleing design

Thanks Joe

Cheers
RicB


        RicB said: "Hi Folks.

        I have a question to put to you all. When one decides to change the
        string lengths as part of a rescaling endeavor, how does one
        account for
        the need to re-figure the striking point for the hammers ? On the
        surface of it a very modest change in lengths would not seem to
        require
        much in the way of changing the strike line.... at least in the
        bass,
        but how exactly does one proceed ?"

        Thanks

    Ric,
    I'd check to see what the the "ratio" for the original string
    lengths were and off-set the new hammer lines to that ratio. I
    assume most of the new lengths are in the lower end of the piano, so
    there should be sufficient room to re-establish a new hammer line to
    the "designed" "ratio". Of course, if you did something really
    radical, then all bets are off. In that case a lot of compromising
    would take precedence.<G>
    Regards,


    Joe Garrett, R.P.T.
    Captain of the Tool Police