This message has been cross posted to the following Discussions: CAUT and Pianotech .
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Been there, Done That?
Getting to the new actions parts on a 90-y-o Stwy L just restrung with a new pinblock , and was greeted with this. With a few exceptions, the hammer spacing is all like this (best judged by the notes directly below the camera - see the damper heads). All flanges have been pushed as far R as the screw permit, and the shanks leave the rail square (the way I prefer). Looking at the keyend-underlever alignment, the R side of the underlevers are consistently flush with the RH side of the keyed (a good place to start). And relocating to keyframe so the at full U.C. shift, the levers would be flush to the LH side of the keyends, requires a shift of .173" ( - curious how I can measure to 3 decimal points,? feeler gauges an the #-set of transfer punches). So it would seem a simple case of relocating the keyframe.
Relocating the keyframe such that at full U.C. shift (a .130" LH slide) the underlever doesn't overshoot the keyend means only shimming out the bumper block by .043" (.173 - .130). And there's plenty of room to set the shift stop screw in this new setting. However, the gap between the keyframe (and key #88) is .194". The gap following this .043" relocation would be .151" (.194" - .043") and the gap after a .130" move would be a slim .021".
But getting the keyend-underlever alignment is the easy part. The hammer-string alignment (without resorting to shanks which leave the rail at 87° instead of square, or to papering them off-vertical) would require a shift to the right of ~.170". (That's how far they're currently off.) Then add to that the U.C. shift ( .130") and we're talking ~.300 (a sliver under 5/16").
So that's the specs for the engineering problem. Here's some background:
The piano was restrung maybe 40-45 years ago (with original block). At that point, the bumper block was shimmed out with cardboard ~1/8". My pinblock while being dead on, front-to-back at bass and treble corners, shifted the plate to the R by ~ 1mm. The back action is dead on the previous L-R (with the individual wire-bending to compensate).
I figure my options are these:
1.) relocate the keyframe .043 for keyend-lever alignment,
then come up with a workable hammer-string alignment by:
2.) aligning hammers so that the center string is dead on the center of the hammer (my 2d favorite) instead of the LH side of the hammer a string- thickness to the L of the LH string (my favorite, by a long-shot).
3.) forget about the shank leaving the rail square. (I prefer to have the flange and rail molding lock in a stabile spacing, but this may be a place for cross papering.)
and finally, trim the treble keyblock to return the original non-shift gap (.194"), which would require moving the keyblock dowels.
Anyone else have practical experience. (No need for sermons on the dangers of re-engineering or of following on less than competent rebuilders (- there's evidence of this.) I'm going to go futz around with this some more.
TIA,
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William Ballard RPT
WBPS
Saxtons River VT
802-869-9107
"Our lives contain a thousand springs
and dies if one be gone
Strange that a harp of a thousand strings
should keep in tune so long."
...........Dr. Watts, "The continental Harmony,1774
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