Grand piano design - parallel vs angled strike line?

[Roger Jolly]

Hi Ron,
>Then Roger wrote;

>This modern idea of floppy key frames and floppy (light) plates 
>doesn't do much to enhance the performance (manufacturer's balance 
>sheet excepted).

If I were designing an action I would start with all rails made from
Delignite, key frame and action.  No glide bolts. Then carefull attention
to detail to the keybed.
Baldwin keybeds are exceptional. 1/8" laminates of Poplar.  In that area
they are straight left to right and front to rear. With kind of solid base,
careful assembly you would never have to bed a frame.  The Heinzman company
had flat frames with no glides, and I have never had to deb one.  It tends
to give incredibly stable regulation. 

>
>>Most concert grands have reduced treble shank mass, for tonal reasons.
>>Adding to the balance problem.
>
>Hear here! Has anyone out there done AB testing of tapered shanks 
>against standard hex?

Harold Conklin did some studies on rebound time, and whip lash effects on
tapered shanks.
Oral history, I can't find any documentation.
>
>>Good quality maple shoes can negate the effect of key whip lash, and lower
>>saturation.
>
>Would you please expand on the above for me? Thanks - I am probably 
>suffering from terminology deficiency.

Your SD10, depending on age, will have about a 6" maple shoe on the bottom
of the key and on the top, to stiffen the Sugar Pine key stick.   More
energy is transfered to the wippen, instead of being lost in the bending of
the key, thus raising the saturation point

>>How many
>>empirical experiments were conducted to arrive at this configuration?  As
>>an aside, I have noted that many cracked boards, start to crack at the
>>corner of the dog leg.
>
>And what an interesting aside, since it is possible that the board 
>might be quite stressed at this location, mechanically as well as 
>acoustically. Our 170 cm grand design has a uniform transition at the 
>location of the 'dog leg', which runs directly into the sound board 
>cut-off rail. The belly comes in quite close to the damper wires with 
>a minimal width of sound board contact with the belly rail. The break 
>is at F#58/G59 (this piano has three string sections only). There are 
>15 dampers in the top treble section finishing at note A73 (the 73 
>dampers is a response to our fantastic SD-10 Baldwin - 1980 rebuild, 
>which really requires more dampers since it has incredible treble 
>sustain - we are planning to build our 170 as a long-tone piano). The 
>top section damper wires pass through clearance holes drilled into 
>the belly rail sound board contact area (I believe this has been done 
>before, though I have not seen any examples. Does anyone out there 
>know of a piano with this feature?).

I have aften thought about an slow angled belly rail to get rid of the dog
leg, also another thought. A 45 degree angled maple cap reflector glued to
the end grain of board and belly rail the full length.  Ever notice how
many cracks start from the open end grain, of the board at the belly rail.
On pianos with the cap reflectors on the top octave area the cracks lessen.
Just a casual observation. 
More fuel for the fire.
Roger
Roger Jolly
Saskatoon, Canada.
306-665-0213
Fax 652-0505