At 3:55 PM +1100 12/1/01, Ron Overs wrote:
>>At 6:43 PM +1100 11/30/01, Overs Pianos wrote:
>>
>>>. . . . During the early 1900s actions were set up typically with
>>>hammer/key ratios between 7 - 8:1. . . .
>>According to your method of reckoning that would give, for two
>>different values of the roller arc:
>>
>>125/233 x 93.5/67 x 138.2/22 = 4.70
>
>You won't get the figure of 22 from hammer centre to jack/roller
>contact on an early action, since a dimension of this size is only
>possible with a large diameter roller with at least a 17 mm roller
>slot to hammer centre distance.
I gave figures for both 20 and 22, but let's put some real numbers to
it. You speak as if 17 mm was a large measurement and that 10 mm
rollers are a modern thing. That will only convince the credulous
without measurable facts. On the contrary 17 mm with a 9 mm roller
is, so far as I can see, peculiar to Steinway and maybe other
American pianos. I have just measured original hammer shanks from
Isermann and Herrburger-Schwander actions fitted to four Bechstein
and Lipp pianos between 1880 and 1905 and all of them have a 10 mm
roller with a centre to slot far side of 18 mm, which is exactly the
same as a modern Kawai. Including the two quite similar Steinway Os
I have available (1906, 1923), we can say the figure will lie between
20.8 and 22.2 mm with Steinway being exceptional.
d l h
9 17.0 20.81
9 17.5 21.22
9 18.0 21.63
9 18.5 22.05
9.5 17.0 21.10
9.5 17.5 21.51
9.5 18.0 21.91
9.5 18.5 22.33
10 17.0 21.40
10 17.5 21.80
10 18.0 22.20
10 18.5 22.61
[ h=SQRT(d^2 + l^2) ]
>
>>125/233 x 93.5/67 x 138.2/20 = 5.17
I now substitute 20.81 from the above table and get 4.97
>Unless the figures you posted were taken from an action with the
>wrong spread distance, there is something wrong with the figures -
>see small diagram included in the link below on calculating the
>ratio.
Ron, I've been measuring actions for 25 years and need little further
instruction. You are asking me to admit that the figures you or a
helper wrote down some years ago are correct while the vastly
different figures I have just measured, which are almost identical on
two Model Os that I actually have under my ruler are mistaken.
>You measure the first key lever length from the 'ivory corner' (as
>did Dr Pfeiffer). We measure from the top of the key top at the
>intersection of a line through the front pin. This will cause a
>further disparity between our calculations. I choose this position
>as the point of reference for measuring the front lever, since most
>pianists do not play with their fingers positioned on the front edge
>of the key. As you yourself previously posted, most pianists will
>play with their fingers positioned well away from the front of the
>key. This variation of measurement points will give you a slightly
>lower measurement than we get.
In taking these measurements I am not concerned with pianists. The
key dip is measured at the front of the key. We're concerned here
with relationships and not with 'touch'. The eventual 'touch' will
depend on these relationships but is not at issue here.
>The example I provided was just one example of an early 1900s small
>Steinway, and yes we have other similar figures from many
>instruments of that period. Clearly the figures you posted are quite
>different. These actions would appear to be completely different
>designs (the key dimensions are certainly very different).
>Nevertheless, the trends which I wrote about do exist.
Ron, please do be rational;
Ron's Steinway 1906 model 0
183/217 x 95/67 x 138/20 = 8.25
John's Steinway 1906 model O
125/233 x 93.5/67 x 138.2/20.81 = 4.97
John's Steinway 1906 model O (Front lever measured to the RO point)
125/212 x 93.5/67 x 138.2/20.81 = 5.46
In order to justify your figures you are making the preposterous
assumption that Steinway built certain model Os in 1906 with a back
lever of 183 mm and others with 125 mm. Isn't is quite obvious to
you that whoever took your measurement (it couldn't possibly have
been you, of course) measured from the balance to the lever centre
instead of from the balance to the contact of capstan with lever
heel, as they might well do if they are guided by your misleading
drawing, which shows (B) apparently as a continuous line from lever
centre to balance. I can understand slips in measurement, but then
to hear someone build a whole theory on the basis of what are
obviously wild conclusions and say "but I haven't actually tested the
inference you've drawn", I find extraordinary.
>>(Key ratio 100:186)
>
>The key ratio is one action design factor which, when considered on
>its own, is completely irrelevant to action geometry (David Stanwood
>also, has posted a similar statement previously). It is the overall
>average of the hammer/key ratio which is critical to action
>performance, of which the key ratio is only a one-third part.
And I'm supposed to be totally ignorant of that, I suppose! I typed
the key ratios of the Steinway and the Yamaha simply to show their
similarity and to try to get you to see the absurdity of your
supposed key ratio.
JD
This PTG archive page provided courtesy of Moy Piano Service, LLC