If one is going to apply a stiffening top plate to a key, why not make it a BOTTOM plate, that also acts as a weight? In this fashion the center of gravity is kept low, with, I would think, some very positive advantages! And the keystick is not weakened by drilling holes for leads. In fact, why not a system of staggered, extruded bottom plates which "nest" to provide just the right balance and stiffness? Thump [link redacted at request of site owner - Jul 25, 2015] > Delwin D. Fandrich wrote: > > > Most of the energy lost between the key end and > the hammer goes into bending > > the key. At action saturation the front of the key > fully bottoms before the > > hammer starts to move. I'm not sure how much key > leading contributes to this > > but I shouldn't think it was all that much. > > > > Del > > Del, > > Your article on this topic in the Journal brings a > new perspective to > how the action work. It seams like we are hell bent > on calibrating > static balance and action leverage with out putting > it into proper > perspective. Placing a tiny piece of lead it a key > to achieve a balance > of 38g instead of 39g or making sure that all of the > knuckles are in a > line to achieve a particular leverage seems overly > picky and unnecessary > considering the magnitude of issues left unattended. > These static > particulars are only relevant if the piano is played > very softly. Once > the action gets up to speed (accelerated) inertia > and compliance become > far more important. > > In order to improve action efficiency I have been > installing stiffening > top plates on actions with longer keys. I have done > this on several > Steinway model Bs with good success. This seems to > extend the dynamic > range while using a relatively soft light hammer > (lighter hammers are > more efficient because they have lower inertia and > bend the shank less). > > You can test the compliance of a key by measuring > how much it bends with > a known weight pulling down on the front end. Using > this method I have > been able to ascertain which actions need this > treatment. The > accelerated actions with all the leads near the > balance rail are > particularly weak. Short keys are usually stiff > enough. > > I made the plates from 5mm maple and spruce (spruce > in the high treble > only). New maple key buttons are installed as well. > Longer .062" concert > grand key pins are installed (Pianotek). A new key > stop rail needs to be > fashioned to provide clearance for the fallboard. > Along the same lines, > when I make a new keyboard for the Model D I use > maple and spruce for > the top plates - not soft basswood usually seen here > (some don't even > have top plates). > > View the photo on my wed site here: > [link redacted at request of site owner - Jul 25, 2015] > > > John Hartman RPT > > John Hartman Pianos [link redacted at request of site owner - Jul 25, 2015] > Rebuilding Steinway and Mason & Hamlin > Grand Pianos Since 1979 > > Piano Technicians Journal > Journal Illustrator/Contributing Editor [link redacted at request of site owner - Jul 25, 2015] > > > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives __________________________________ Do you Yahoo!? The New Yahoo! Search - Faster. Easier. Bingo. http://search.yahoo.com
This PTG archive page provided courtesy of Moy Piano Service, LLC