Isaac: Some murky territory is creeping up..... >Experiments have been made with strings that where bring in different >tensions, and examined, immediately, after sometime. Then data exists >somewhere. > .... >The experiments where conducted on a 12 years lasting on tensed >strings at different tensions - Klaus Fenner wrote a text in German >that describe these '(1978) - have no translation at this date. >The results are very clear and well known. As is often the case [especially in the piano indsutry it seems] "well known results" are not always supported by the facts when you start looking for/at the evidence. If you have access to some experimental results or publications on creep in piano wires I'd be very interested to read them so the work can be properly evaluated, whether in German or not. Otherwise, I think we've probably said all we can usefully say in stating our positions on the subject, especially given that it seems to be a bilateral creep discussion here. On the other specific points.... >The name of the initial effect when a string is first tension applied >is the Kosler effect. ... ...you mean the Koester effect. This, in itself, is another can of worms. To my knowledge, it has never been demonstrated that the Koester effect is indeed responsible for the brightening phenomenon of newly strung wire. This was nothing more than a speculation of Goodway and Odell in their historical harpsichord wire book, and not supported by any evidence [the scientific content of that book has a number of holes in it in general]. Certainly, nothing they said would support the conclusion that the Koester effect is relevant to piano strings. Where did you see about this? >It is suggested that you conduct the experiment yourself if you mark >the length of a string (marker, tape) tense a 800 N , measure the >elongation and keep it at that tension for 6 months ore one year, then >intense and measure it, if no creep should occur, your string should >be back to its original length. Quite likely this kind of experimentation will be done as part of my ongoing wire project. >Hello, that's it, using pen marks or masking tape, the difference may >be small and difficult to measure precisely, but we can use the pitch >of the string to assume the tension. In principle yes. In practice no. Definitive results require that you identify and isolate creep strain from all other factors which can affect pitch in a strung wire. So tension and pitch is out. This is the same problem with all tensile testing of wire, which requires hard data on strain, obtained from direct measurement of an accurately defined gauge length, not calculated values inferred from other data that is easier to collect. >I wanted to say about the 4 kind of strings that are produced by >Stephen PAULELLO, that a full methodology will be available, as well >as more data on them, in September. The strings are made with a slower >anneling time than Roslau blue or red, and that is the main reason for >their propreties. How does the Paulello Type II wire which I tested relate to these four types? From its breaking strength it cannot be meant as a competitor for Roslau wire for modern pianos. >What type of wire are you planning ? for what era(s). Pre-1830 soft iron wire. Any instrument. Stephen -- Dr Stephen Birkett Associate Professor Department of Systems Design Engineering University of Waterloo Waterloo, Ontario Canada N2L 3G1 Davis Building Room 2617 tel: 519-888-4567 Ext. 3792 PianoTech Lab Ext. 7115 mailto: sbirkett[at]real.uwaterloo.ca http://real.uwaterloo.ca/~sbirkett
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