Ed, Don, Jim, Ric, and all other Santa Claussers there. My "impression" on lead placement is that having that larger lead mass near the balance rail is certainly not innocent, but I suspect that the process involved have more to do with the key flex than purely action move and ratio, acceleration and other computable facts. It is just that indeed the abrupt stop of the heavy key front on the punching, is playing a very noticeable role in the way the energy is given to the strings. The key is much more probably acting like a spring than a rigid wood piece in faster modes of play. If we think about it a tad that makes sense, and loading the spring in the part where it is most solicited certainly may slow it a tad. The action is jerking when the key bottom, use a setup with a dial gauge on the balance rail anywhere and you'll be surprised to see how much move occur there (you can push the keybed from below with 2 fingers usually and have a very noticeable move yet) For comparison, every time I knock my head hardly against a wall I see the light (well not very physician terms I guess). I suspect that the high speed camera can tell it to us, as well probably as synchronization checking like Jim propose to conduct. (But I've seen those sensors used at the IRCAM, and they are not mass less). For fun , one can conduct a little experiment using 5 different kind of felt punching under five white notes, and hear the result (or better record it to further analysis). Another one (I'll try that) could be to check the way the action react with "zero dip" (hard support under the punching). My idea is that may be the key bottom before letoff have occurred, in the faster modes of play , then letoff occur because the hammer shank is also flexing and release ... If some have data about that I certainly like to hear them. The heaviness of actions are most perceptible when one want to play strong and keep some possibilities of expressiveness. I also have the idea that the leverage is changing enough in the end of the stroke (during letoff) to be an important parameter while playing, and this is never checked with our balancing methods (While Schimmel tells about the use of a weighted wooden block to verify that all notes "talk" at pp level with a 100 g pressure if memory serves) Well and eternal work in progress ! Kind Regards to anyone (but Joe who makes me the affront to say he have doubt about my hide glue ;>) happy... etc. Isaac ------------------------------------ Isaac OLEG accordeur - reparateur - concert oleg-i@noos.fr 19 rue Jules Ferry 94400 VITRY sur SEINE tel: 033 01 47 18 06 98 fax: 33 01 47 18 06 90 mobile: 033 06 60 42 58 77 ------------------------------------ > -----Message d'origine----- > De : caut-bounces@ptg.org [mailto:caut-bounces@ptg.org]De > la part de Ed > Sutton > Envoyé : mercredi 24 décembre 2003 14:54 > À : College and University Technicians > Objet : Re: What is Inertia > > > Richard- > > My dictionary agrees with Don. > > But what we are trying to do here (I think?), is try to > make piano actions better > for the pianists. > Since there are so many kinds of pianists, there might be > many ways to make pianos > better, of more adapted to various players and ways of playing. > > And in particular, we were concerned with the placement of > key leads. For a long > time many of us have followed the rule of thumb that it was > better to produce a > given front weight by placing a large quantity of lead > close to the balance rail > than by placing a smaller quantity close to the front, that > this makes the action > "feel better" and repeat faster, at least in the bass octaves. > > If this is true, then it is worth going to a lot of trouble > to do it, if not, it > is a waste of time. > > Jim's experiment to measure jack reset time should answer > the question on > repetition. > > I can imagine some simple experiments to determine if > performers can feel the > difference between keys with the two different > configurations. It will require > building an action model with about ten keys, so I'm not > willing to commit just > yet to do it. Anybody got some grant money? I first > thought of using an old > action I have, but realized the keys are too short. > > If we could answer yes or no to either of these questions, > it would be valuable > information. > > Notice I've written all this without using the "I." word! > > Just for fun, take a look at the pictures facing page 298 > in Ortmann's > _Physiological Mechanics of Piano Technique_ (comparison > photos of 5 different > arms). He found that adult pianists' forearms weighed > between 6 and 14 pounds. > And we wonder why, no matter how hard we work, we can't get > the universal perfect > action..... > > Happy holidays to everyone. I'm very grateful for this list. > > Ed Sutton > > ----- Original Message ----- > From: "Richard Brekne" <Richard.Brekne@grieg.uib.no> > To: "College and University Technicians" <caut@ptg.org>; > "Newtonburg" > <pianotech@ptg.org> > Sent: Wednesday, December 24, 2003 6:22 AM > Subject: Re: What is Inertia > > > > > > > > "Don A. Gilmore" wrote: > > > > > > There are no units of "inertia"; one object cannot > have more "inertia" than > another. It can have more kinetic > > > energy, or momentum, or mass, or velocity, or indeed > "moment" of inertia > > > than another object since those are measurable, > quantifiable properties. > > > > > > I understand exactly what you are saying, as I understand > exactly what > > the others are saying. But I have to point out (without taking a > > position on the matter myself) that there are three > declared definitions > > for inertia on pianotech by various folks with some > degree of physicis > > knowledge. Let me list them. > > > > > > 1. Don Gilmore... inertia is a concept, not a quantity, > has nothing to > > do with size, mass, velocity or anything else. Is simply > the fact that > > objects with mass tend to resist any change in velocity. No object > > regardless of mass has any more inertia then any other mass. > > > > 2. Sarah and Mark.... inertia is very much like Don describes, yet > > inertia is mass related... a larger mass will definatly have more > > inertia then a smaller mass. > > > > 3. Jim Ellis. inertia is clearly mass related its very > hard to read his > > definition without concluding he means that inertia is related to > > acceleration and /or velocity... That relation to > acceleration seems a > > bit unclear... but as I read through his posts I get that he first > > said... Inertia = mass x velocity-squared, then after some debate > > changed this to Inertia = mass x acceleration-squared. > His last post > > seemed to draw this up a bit differently > > > > "Inertia is a minifestation, a property, an effect, of > acceleration and > > deceleration. It's proportional to the square of the > change in speed, > > or velocity." > > > > What I'd like to see at this point is that since Don, > Sarah, Mark, and > > Jim all are people we all rely on for physics insights, > and because they > > all present clearly different definitions of this > concept,,, that these > > four all bang this one through until they arrive at a > common definiton > > for us. > > > > > > grin.... NOW I will state my own position... > tentatively...ok ?? :) > > Seems to me that Don is correct... except I have a hard time > > understanding or accepting that "one object cannot have > more "inertia" > > than another". If this is true then either inertia is a > constant, or > > inertia is just plain undefined... as in divideing by > zero more or less. > > So I lean towards Sarah and Mark. But I want to see you 4 > hashing this > > out so we can past the problem.... as clearly any discussion about > > action mechanics on this list is going to be rather > meaningless unless > > we can agree on what terms like inertia mean. > > > > Cheers > > RicB > > _______________________________________________ > > caut list info: https://www.moypiano.com/resources/#archives > > > > _______________________________________________ > caut list info: https://www.moypiano.com/resources/#archives >
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