At 11:31 PM +0200 10/3/02, Richard Brekne wrote:
>Before we go on... :) could we resolve what seems to be two mutually
>exclusive standpoints here ?
No fatal disagreement here, just ideas which have not been talked
through completely. I respects David Love's experience immensely.
>Bill Ballard wrote:
>
>> The problem is of course that there is no direct correlation between
>> action leverage as measure by distance and by weight.
>
>David Love writes:
>
>>The action ratio not only refers to the relationship between change in
>>weight at the hammer and the resultant change in weight at the key, it
>also
>>refers to the relationship between key travel and hammer travel...
>
>snip snip.....
>
>>At a ratio of 6:1, for example, 10 mm of dip
>>will result in the hammer traveling a total of 60 mm. (It also means
>that a
>>change in 1 gram at the key will result in a change of 6 grams in the
>>balance weight.)
If in fact for the same note on the same one-note action model, a
reading of SBR yields a ratio of 6:1, and a reading of the linear
(not angular) action ratio, measuring the legs of all three levers
with dividers, also yields 6:1. But I'm not going to guarantee that
they will. There's enough fluttering/dithering in the 88-note set of
SBRs on an action with visibly straight knuckle and capstan lines,
that I suspect that however useful the SBR is as a measurement, it
may have built-in inaccuracies which need to be taken with a grain of
salt. Remember the Stanwood Metrology is a static one, however
ingenious. The dynamic measurements are quite a bit more complex as
Stephen Birkett can testify. Real precision may lie in the dynamic
model.
Likewise for action ratio as measured by distance. I'm not happy
measuring the vertical components of lever arm motions (the key
fulcrum to key front, and the hammer center to hammer strike). I'd
much prefer making angular rather than linear measurements.
But as a statement of principle, I'd agree with David, that a
leverage ratio can manifest itself both in linear and weight
dimensions. In practice, I'll look forward to someone ironing out
whatever discrepancies may be produced by what I perceive as the
inherent inaccuracies of each.
>I dont mean to be a pain or anything... but you two seem to be saying
>exactly the opposite about this, and its kind of a central point.
Where David and I diverge is in the usefulness of measuring hammer
stroke completely through the full key dip (escapement and aftertouch
included). I don't think I heard him say that let-off should be
removed from the exercise by cranking up in the let-off button so
that the hammer travels without this interruption, for as long as the
key travels. If he intended to, I'm happy.
But you wouldn't be, because what you asked for was what was the
workable range of action ratios when a 10mm dip was specified. Or
maybe it wouldn't matter because, your question could just as easily
be answered by an action with the let-off button cranked out of the
way, as by one in which the hammer's stroke disappears off the radar
screen once it enters escapement.
But if I may guess at your thinking, you wanted to know how the three
portions of the key's stroke (at rest to the onset of escapement,
escapement itself, and aftertouch) would work (and maintain proper
proportion), for a specified total dip, and over some range of action
ratio? IOW, is there some range of action ratio through which a
specified 10mm total dip would be the basis of a successful action
regulation? And at what point in a decreasing action ratio, would
this specified dip have to be abandoned?
Not that I want to add to your overburdening 18-hour days..........
Bill Ballard RPT
NH Chapter, P.T.G.
"No, Please wait, you're all individuals" Brain Cohen, exasperated
"Yes, we're all individuals" the throng assembled in the street
below his window, in unison
"I'm not..." Lone dissenter.
...........Monty Python's "Life of Brian"
+++++++++++++++++++++
Not that I want to add to your already over-burdening 18-hour days.........
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