[CAUT] Fwd: S&S M Strike point

[John Delacour]

On 24 Dec 2012, at 18:08, Ron Nossaman <rnossaman at cox.net> wrote:

> Moving the stack around will also affect the action ratio, which is why I suggested the action should be made to work as a first priority and the A-0 strike point will be close enough. I read that as JD's intent as well.

Yes.  One thing worth remembering is that the strike line is the first line drawn in the design of a piano.  Everything else is drawn in relation to the strike line.  On most middle-sized grands (there are notable exceptions) the hammer rail, the key slip and the lock board are drawn parallel to the strike line.  The strings are the next thing to be drawn after the strike line, and to draw them, a decision has to be made there and then as to the strike proportions.  This decision is made months or years before anything like a piano has materialized, and, since the dimensions of the keyboard and action have also been finalized, there’s no going back.

If the proportions chosen empirically for the strike points is anything but ideal then too bad.  On the larger Steinway grands, the strike proportion for the first 20 notes is 1/8; that is to say that if the string is 160 cm. long, the strike point will be 20 cm from the termination.  After the break, the proportion will be more like 1/9 and at note 88 something like 1/16.

On most grands, the points on the strike line coincide with the points on the capstan line and the borings of the hammer rail.  A Steinway is designed to have the bass hammer heads twisted clockwise and the tenor hammers anticlockwise in proportion to the string angle, and so this coincidence is not the case with a Steinway.

The point is that the original draughtsman will have chosen a simple fraction for the strike point at note 1.  If it looks something like 1/8 then it’s almost certainly 1/8 that he chose.  If roughly 1/9 then exactly 1/9.

If the distance from the key front to the capstan is the same for note 1 as for note 88, then the strike line is parallel with the lockboard and the strike point for note 1 will be the same distance from the lockboard as the strike point for note 88, and that way the shank length will be equal throughout provided other things are done properly, in spite of some theories.

JD



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