In other words it is designed and attached to the inner rim just as one would expect assuming its function to be as I described. And, yes, when properly installed and adjusted it does very slightly pull the hitch pin panel down. By about 1/12 of an inch if I recall the bolt threading correctly. Maybe a bit less. In my opinion its function is not intended to be a method of 'adjusting' down bearing. But, as I stated earlier--you're welcome to use it that way if you wish. It would be an interesting way to find out what kind of sound a cracking plate makes.... Del ----- Original Message ----- From: "Robin Hufford" <hufford1@airmail.net> To: "Pianotech" <pianotech@ptg.org> Sent: September 22, 2002 11:31 PM Subject: Re: [pianotech] Grand Treble Bell > Del, > While I will agree that the explanations given at Steinway are, > frequently, obnoxious sales pitches, and I have posted such here, I don't > think that the explanation given for the "Bell" which I referred to as > possibly having been received as the factory was such, and, after looking > carefully at several nosebolts this week, I believe this explanation very much > makes sense, although I would certainly take with a very large grain of salt > anything said by anyone associated with this factory in particular, and others > as well. As I indicated in the post I don't know for sure where I acquired > this explanation, but, if I, in fact, was given this explanation at the > factory, it would not have been by a sales oriented person but rather by a very > accomplished, widely-known and well-regarded technician who was very forthright > about the problems and virtues of the pianos produced at the moment. > A point in the post above indicates that the nosebolt, if adjusted > correctly, can and does in fact pull the plate down with the intention of > increasing downbearing, even if this is a risky course, and this, I believe, is > how it was intended to work. Obviously, as you say, the risk of breaking the > plate when this is done increases and this is the reason the factory ceased > giving specifications on this adjustment. > I have not seen the patent posted on this subject by Richard Breckne as > the posting came in with no data on my browser. However, I believe this is > pretty much what the patent indicates the device is for, judging from the > subsequent commentary about it. Of course, as the patent application is not > directly a sales pitch, I would take the applicant on his word as to what it > was and what it was intended to do. However, as you say, lets see what it does > actually do. > I believe this "bell" is simply, a strong cantilever, probably of cast > iron, at least originally, which was in a period of very high usuage of > castings, designed to resist an upward pull and it is of a design which > strongly suggests this is the case. This week I have looked at three such > nosebolts, two installed on "A"s from the 1890's and one from a 5 year old B. > These are castings, apparently, of iron, probably of the same material as the > plate, although I don't know this for a fact; perhaps a different mixture was > used, but this seems unlikely at least at the time they were originally > designed. The three differ slightly, with the two from the 1890's being, > characteristically, somewhat larger than the later one. > Four functionally important features can be discerned upon inspection of > the so called "bell". They are: the conical shape or "bell" itself, the > large, 90 degree notch cast into it which is designed to fit the rim, the > number and placement of screws which fasten it to the rim, and the bolt itself. > > The conical shape of the casting is plainly, a design feature to > strengthen the cantilever and to help it resist the moment created by the > upward pull of the plate. But this would also be the case were the bell being > driven downward by the bolt and the plate. The distance which the load must be > transferred, roughly, six inches mandates this. However, the fitting of the > base of the "bell" shaped as it is, to fit the rim in two dimensions, and its > method of attachment suggests the former is its intended function. This is > particularly, important, that is, it would be a more efficient design, were the > nut to be tightened and the plate flexed downward, resulting in an upward pull, > something that the assembly was evidently designed to resist as will be > indicated below. > Of course, the cantilever must transfer its load somewhere and how this is > accomplished is most instructive, in my opinion, as to its design purposes. It > is notched where it fastens to the rim. I don't mean to suggest it is worked > this way, but, rather, I believe it was cast this way. One part of the notch > fits the bottom of the rim; the other, much larger surface, fits the interior > side. There are, in all seven screws that attach the nosebolt to the rim in > the two dimensions of the notch. Five large, vertically oriented, screws > pass through the nosebolt and a spacer into the bottom of the rim and secure > this joint. Two more fasten the nosebolt to the interior side of the rim. > A set of critical observations can be made. These arise, principally from > the placement of the two screws that attach the nosebolt to the rim, and, to a > lesser degree, from the placement of the five screws attaching it to the bottom > of the rim and, finally, the shape of the notch itself. > The two that attach the nosebolt to the interior side of the rim are > located just above the lower edge, a location pregnant with implications. > These two screws are, at least on the A's, smaller than the other ones, > indicating, at least to my mind, the designer's expectation that the five > screws on the bottom rim would take the principal load, which they do. These > five are not, however, very effective in resisting a moment experienced by the > bell caused by forces on the bolt as they are a significant distance away from > the bolt. The way in which this moment is dealt with is most instructive. > It is obvious that the designer expected the two bolts attaching to the > side of the rim to resist an upward pull as they are placed very close to the > lower edge of the rim and this in conjunction with the notch itself, of which > the area in contact with the interior side of the rim is most effective. Were > the nosebolt being driven downward then this would be the most ineffective > position conceivable due to the leverage of the cantilever, and the moment > arising from this could, possibly, indeed probably, result in the nosebolt > being torn loose from the bottom of the rim and failing. > The correct placement of the two screws attaching the nosebolt to the > interior side of the rim in the case of a downward force exerted upon the bolt, > would be on the higher side of the nosebolt to effectively resist the moment > associated with such a force, particularly if only two screws are to be used, > and, it is likely more than two would be necessary in this case. As I said, > however, they are placed on the lower edge of the rim, obviously to resist the > moment associated with an upward pull such as would be exerted by the plate > were the nut tightened. The fact, that no more are needed shows an admirable > design efficiency. There are, at least on the pianos I examined, no screws > whatsoever in the upper part of the notch which transfer the load to the > interior side of the rim, as would be expected and are necessary were it > designed to resist a downward force exerted upon it. > Furthermore, the notch itself can only work effectively against an upward > pulling force which it does and the screws are placed to be most effective in > dealing with a moment arising from such a force. By such means, at least in my > opinion, is the functional aspect of this indicated. > On a different but associated subject. It appears to me the factory, upon > redesigning their pianos in the 1870's, discovered, or at least gave some > thought to the possibility of there being an instability, either of the plate, > the bracing, and the rim, or any and all, and took additional, post-design > measures to deal with it. These measures are the small stiffener made of wood > running from the belly rail to the first beam/rim junction and the brace bolted > upon the top side of the plate in the B, C, and D, recently discussed here. > Perhaps, and this is merely speculative, the "bell" nosebolt was also an > attempt to deal with this instability. > Other companies, for example an older Yamaha GE-2 I saw this week also > have a similarly located nosebolt although without the bell whose function > appears to be to hold down the plate. In the Yamaha, this is simply a large > wood screw which passes through the plate and board and is attached directly > into a beam underneath. > As you know, I don't subscribe to the flexural view which you and others > advocate and, hence, would not find the mass-coupling idea, although > interesting, useful or necessary in this context. Although the plate is, no > doubt, vibrating I don't believe it vibrates in such a way to require such > massive damping as the use of the "bell" were such the case, would suggest. . > Regards, Robin Hufford > > Delwin D Fandrich wrote: t > > > ----- Original Message ----- > > From: "Robin Hufford" <hufford1@airmail.net> > > To: "Pianotech" <pianotech@ptg.org> > > Sent: September 17, 2002 12:02 AM > > Subject: Re: [pianotech] Grand Treble Bell > > > > > Richard, > > > I was informed, I think at the factory, or perhaps I read at some > > point in the PT > > > Journal, that the nosebolt at the "Bell" was intended to be an adjustable > > mechanism > > > to preserve downbearing as the board changed after leaving the factory. > > Also, > > > Steinway eventually refused to make recommendations as to how much > > tightening was > > > recommended, apparently understanding the risk of breaking the plate or > > encountering > > > difficulties in this regard. > > > Regards, Robin Hufford > > > > Robin, > > > > Over the past roughly 40 years I've heard Steinway factory representatives > > give three or four different renditions of what the bell does. And, yes, > > this is one of them. > > > > Until someone--anyone--can explain to me just how adjusting this thing will > > have any effect on downbearing other than by bending the plate--a > > problematic and potentially dangerous process at best--I'll stick with my > > own proven theory. > > > > I can only add that none of the rest of their explanations have made any > > more sense than this one does. > > > > Del > > > > _______________________________________________ > > pianotech list info: https://www.moypiano.com/resources/#archives > > _______________________________________________ > pianotech list info: https://www.moypiano.com/resources/#archives
This PTG archive page provided courtesy of Moy Piano Service, LLC