There seems to be different numbers floating about, that is for sure. I am looking at a table of piano wire specs from an old Renner catalog which lists 1.5 mm wire (.0591") with a breaking strength of 360 kg = 794 lb. That is very close to what the Pure Sound website lists on its table at: http://www.puresound-wire.com/otherwire.htm Apart from the data on that table, I have a hardcopy table which lists the yield point or limit of elasticity for Pure Sound. Is that of any help? On Feb 1, 2007, at 9:31, RicB wrote: > Pure sound supplies a table of breaking strengths for both Pure sound > and standard piano wire, along with a few others from Malcom Rose. > I'm just trying to back engineer a bit of some of these formulas > tossed around in publications so as to ascertain exactly what these > were saying. > > For example... in the Calculating Technician the maximum safe tension > for standard wire is 0.557*d^1.667 (d is diameter in mils). If you > have a 1.5 mm Ø wire (circa 59 mils) you get 0.557*897 lbs = 498 lbs > maximum safe. > > Now... this looks to me like 897 lbs is the breaking strength used > here... and 55.7% of that is figured as maximum safe.. If that is so > then we have 406 kg breaking strength for modern wire according to > this formula. But looking at Pure Sounds table for breaking strength > of modern wire he has 370 kilograms. Thats quite a difference really. > If thats not enough confusion... Delecour handed out a lookup table > for a spreadsheet a while back which has this same 1.5 wire (59 mils) > at 276 kilos. > > I suppose I could just contrive a formula from any given data set like > Pure Sounds page. For example if you take a 1 mm (39.37 mils) and > figure the exponent needed for 39.37 mils to arrive at the 369.5 lbs > that Pure sound gives you simply take x = ln369.5 / ln39.37 , which > is 1.609622688. But then if you use that for the rest of the table it > doesnt add up. So the breaking strengths that Pure Sound gives can > not be figured by this kind of formula... ie. a^x = b. I don't think this kind of formula works for any kind of piano wire. A thinner wire will always have a higher breaking strength per unit of surface area of the face of the wire. > Point is that if you are anywhere near maximum breaking strengths > given by one table for one type of wire... you may very well be well > over the limit on somebody elses table. Kinda makes depending on the > calculations of spreadsheets a bit iffy until you have reliable > figures yes ? No doubt it does. Apart from doing one's own testing, the best way to get reliable information is to go directly to or as close as possible to the source. One can assume that Pure Sound's data on its own wire is correct. Is there a spec sheet for wire published by Röslau or Mapes? > > Cheers > RicB Jurgen Goering Piano Forte Supply (250) 754-2440 info at pianofortesupply.com http://www.pianofortesupply.com -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: text/enriched Size: 2998 bytes Desc: not available Url : https://www.moypiano.com/ptg/pianotech.php/attachments/20070201/6fad65c8/attachment.bin
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