Hamburg vs American S & S

[stanwood]

>I have been re-reading what I could find of your posts of a while back, and I
>would appreciate your clarifying one point. Does this mean adding a gram
>weight to the hammer and seeing how much you have to add to the front of the
>key? If so, it seems to me that measuring the strike ratio in this way would
>include some friction

Bob,

The calculation of Strike Ratio uses balance weight which factors out the
friction.  The balance weight added to the front weight equals the total
weight needed to balance the key.  I call this the top action balance
weight.  Because it is the amount of weight needed to balance the leveraged
weight of both the hammer/shank and wippen.  It is the amount of upwards
force at the front of the key.  Part of this force is from the wippen and
part from the hammer.  The wippen component is usually aroun 9 grams.  The
rest is from the leveraged weight of the hammer and shank. Divide this
remainder by the strike weight and you have the strike ratio.

To find the wippen component - the wippen Balance Weight - measure the
wippen weight by tipping a wippen on a scale.  This is usually around 18
grams.  Then find the key ratio - what does a gram of weight at the capstan
translate to at the front of the key, this is usually aroung 0.5.  The
wippen balance weight in this case would be 18 x 0.5 = 9.0

For instance a key with an upwt of 20 grams and a downwt of 50 grams would
have a balance weight of (50+20)/2 = 35grams.  So if you place a 35 gram
weight on the key it is balanced - "in the manner of a rusty scale".  The
other balance weight is the front weight.  This is the weight of the
keystick tipped on a scale.  Lets say the front weight is 25.

The top action weight would equal 35 + 34 = 69

Subtract out the wipBW  69 - 9 = 60  This is the strike BW

Lets say the strike weight is 10.0 grams

The strike ratio is 60/10 = 6.0

To survey an action you take upwt, downwt, frontwt, and strikewt.

a few samples will determine the wipbw which can be taken as a constant.

With a computer spread sheet the calculations take virtually as long as it
takes to enter the data.  Put it on a graph for easy interpretation.

It's not rocket science!

When you "get it" it seems quite simple.  Keep trying and don't hesitate to
ask me questions about the new metrololgy at anytime.

>and that a more direct measurement would be to measure
>the ratio between key movement and hammer movement. For instance, with the
>letoff set at or above the string, if the blow distance were to be set at 45
>mm and 9 mm of key movement would take it from rest to the string, such a
>ratio would be 45/9=5.

I've found the distance measuring method to be impractical.

The strike ratio method once learned is a very easy and practical method.
And it does relate to the distance.  Low strike ratios need more dip and
vice versa.



            David C. Stanwood Stanwood@tiac.net
            West Tisbury, Massachusetts     USA
            On the Island of  Martha's Vineyard
        http://www.tiac.net/users/stanwood/st&co.htm

"The art in hammer making has ever been to obtain a solid,
 firm foundation, graduating in softness and elasticity toward
 the top surface, which latter has to be silky and elastic in
 order to produce a mild, soft tone for pianissimo playing, but
 with sufficient resistace back of it to permit the hard blow of
 fortissimo playing."                 - Alfred Dolge 1911