David and list, Sorry for the delay in responding, yesterday was one of those days where everything happened and nothing got done. David wrote; >Related to this subject, some years ago I saw a modification on a >Steinway D done by a highly reputable local technician (now >deceased) in which the agraffes were replaced with a much deeper >profile agraffe (not unlike a Bechstein agraffe). The idea was >that the larger and more stable agraffe prevented any leakage or >vibration through this termination point and resulted in increased >clarity and power. Interesting. >Have you done any research in this area? Yes, we've done quite a number of experiments. In 1997, I built a set of agraffes (for a D rebuild) from 1040 carbon steel (with an Electroless Nickel Plated coating for corrosion protection). Took a whole week to make them on the lathe with the milling attachment. The electroless nickel process lays down a uniform plating thickness, even in the holes. We had 0.002" (0.05 mm) laid down. It deposits with an as plated hardness of just over 40 on the Rockwell C scale and can be hardened to around 60 by heating to 240 degrees C for four hours. Nice stuff. While the 1040 agraffes sounded quite good, they were pretty difficult to machine, and I wasn't totally smitten by the tone. We are presently developing a new string termination technology which is showing lots of promise, but we won't have it ready for our Reno exhibit piano, No. 003. >Any idea on the reasoning behind the design differences in agraffe >depth by these two manufacturers? Are the effects of these >differences quantifiable? Most OEM agraffes seem to be between 4 to 5 mm in thickness. While most use the 4 mm variety, there is likely little tonal difference between the two, since free machining brass is basically a lousy termination material for piano wire. It deforms under the cutting action of the wire during tuning. The agraffes with the steel pin insert are not much better, since the pin hardness is only about 19 Rockwell C. We have inserted hardened pins into steel pin agraffes as an experiment, but the wire tends to skid across to the edge of the hole, only to produce as much string noise as any other poor agraffe. The latest Kawai agraffes seem to be better than average even though they are brass. While I have no inside information, they appear to be forging the string holes. If this is the case, it would explain the performance improvement, since forged brass will have a work hardened surface which will resist the string cutting action a little better. You can probably guess our agraffe source for piano No. 003. Regards, Ron O -- _________________________ Website: http://www.overspianos.com.au Email: mailto:ron@overspianos.com.au _________________________
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