Calculating Stike Point "Ratio"

[Joseph Garrett]

Ric said: "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 ?
Hmmm? I think you get it, but not sure.<G> I assume you have the Olde Scale. Stuff the action into the piano; measure where the Original Hammers Strike point is; take that number and the number of that notes string length; do the math ....and you'll have a "ratio" or "fraction", if you will. (i.e. 1/6th, 1/10th, etc.) That should give you a starting "point" to aim for in the New strike point. Because the action and belly rail can only be varied a limited amount, you may have to make some compremises to physically make it work. (think: large can of worms<G>)


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 bass should not be too much of a problem. However, the upper treble will be, as there is the likelyhood that the belly rail will not allow you clearance for that longer string. As you know, the slightest addition/subtraction of strike point, in that area, makes a huge difference in tone production. Personally, I wouldn't get to "radical" in the top treble string lengths. As for the calculating formulae that takes "Harmonicity" as the criteria...I can't comment on it, other than to say that that is what we REALLY are trying to do in Scaling, is to attempt to make all of the dominant Harmonics match. In the real world that just is not possible, IMO, although it would be nice. Kinda' like calcing the longetudinal inharmonicity of bass strings: looks good on paper, but doesn't really make for good piano sound in the real world.<G>
Have fun.


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