>A geometry question : > >I wonder what happen to the magic line on instruments with a >trapezoidal keyboard, as S&S mod D. > >Seems to me that the bass side of the whippen axe may be lower if we >want to stay consistent with the magic line. >I've seen a larger spread on the bass side on some instruments >(shimmed flanges), that may go in that direction too. I've noticed too >higher key height on the bass side (more cardboard punching under the >front too) a correction for too heavy basses problem. > >Makes sense to me that the shorter length of the segment in the treble >, assuming the whippen heel is at the same place all along the action, >mean that the whippen axe may change height to respect the optimum >alignment. > >Do some have some thoughts about that ? Indeed Isaac, I have mentioned this before on the pianotech list. >It is possibly an undocumented and unofficial way to have the tubular >frame in a slant (not twisted , but different height ). The wippen heel blank could be tapered so that it is shallower in the bass relative to the treble end. I've just looked at this (ie. the effect with a tapered stike line) on CAD, for the first time. It's a fact, the wippen heel should be tapered to maintain the heel/capstan contact on the 'magic line' at half dip where larger grands are using a tapered strike line. I have decided that our 280 cm concert grand will not have a tapered strike line. I note that the new 280 Bösendorfer now has a tapered strike line, unlike all previous Bösendorfer grands, including the Imperial, which had a strike line parallel to the key fronts. One would hope that the descision for the new spec is not just a marketing one. Too often I suspect, pianos are designed for reasons of 'traditional dimensions' and 'following what's gone before', instead of looking ahead to evolve our pianos into a superior species. >My friend Stephen Paulello used a whippen heel that can be height >adjusted to compensate for that in his grand piano, you should see the >evenness of the hammer rise all along the instrument ! In his own piano Isaac? We use two different heel heights for our 225 grand piano. Although the key stick lengths are uniform from bass to treble in our piano (ie. the strike is parallel to the key fronts), the black notes have their balance pins 18 mm closer to the action stack as is quite typical. This requires that the wippen heels for the black notes are just over 1 mm deeper than those for the white note wippens. This involves a little extra effort, and while I've no doubt that it is an improvement, I still have to establish if the gain/trouble ratio makes it worth persisting into the future with this feature. As yet, I have too many other things demanding my attention to seek an answer just yet. But at least the action works well with this feature. Regards, Ron O. -- _______________________ OVERS PIANOS - SYDNEY Grand Piano Manufacturers Web: http://overspianos.com.au mailto:info@overspianos.com.au _______________________
This PTG archive page provided courtesy of Moy Piano Service, LLC