Stephane wrote: >My purpose was to dig a bit into the string scaling theory. I would >like to understand better the way constructors deal with tension, >inharmonicity, striking point, smooth changes in all this (following >the article of Dave Roberts in PTG journals about 1981). >About string length measurements, I once again find myself with too >large relative errors, certainly in the trebble section. Not much you can do about the relative errors up top, except measure carefully. Keep in mind that the same relative errors pertain to the designer and builder, so even if you could measure the actual speaking lengths ultra-accurately the importance of those *exact* dimensions as they lie in front of you on that particular piano would likely be of no consequence. As long as you stay within the same limitations as the maker you're safe. As for measuring string lengths I've tried quite a few systems over the years, having measured numerous stringands in pianos. I always take complete stringband data - and measure the longest string if the bridge isn't notched, since it is the most critical. My preferred approach is to record the string lengths on a tape since it goes much more quickly than measuring in the piano, is easier and more accurate. I use a strip cut from a sheet of mylar as a stable record. It's also easy to push the thin strip up to the termination points when space is cramped or frames and other bits get in the way. An assistant is helpful to speed things up for the lower 1/3 of the stringband, but you can do it alone too. For each trichord push the end of the mylar up against the far termination point and mark a tick for the close one. You'll end up with a strip of ticks that forms a permanent record. Roll it up and store it in a camera film case if you want to keep it. Back at the ranch you lay the strip on your benchtop against a stop referenced to a (permanent if you do a lot of such measuring) measuring tape. Recording the lengths is accurate and quick as you don't need to move or re-align anything. Let us know how the micrometer works out for you with diameters. Anyone any thoughts on disk vs anvil micrometers for diameters, especially re: accuracy? 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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