---------------------- multipart/related attachment --============_-1226355215==_ma============ Del, Richard and list, As mentioned in my earlier post, we have found that soft duplexes will not stand up to commercial service. Below is an image of a capo bar from a 1986 Hamburg Steinway D. We first restrung this piano in 1993, when the capo and duplex bars were reshaped (but not hardened). This piano is one of the high use pianos I referred to in my post of earlier today. After just four years of service from 1993 to 1977, the capo bar deteriorated to the state shown below (sorry about the quality of the image). Before someone replies to tell me how the bar radius is too sharp, the radius shown above is the same as we use at present with our hardened bars, which do not mark at all. Our hardened bars can be checked with a waste piece of piano wire and a hammer. The wire is placed across the bar, and the wire is hit with the hammer. The wire will be deformed but the bar will remain unmarked. I have removed steel pins from the Renner steel pin agraffes which have had a similar levels of damage to the above capo bar image. As as aside, I should mention the resultant tonal quality with hardened bars. Some commentators have mentioned that they would expect hardened bars to produce a brighter tone. The opposite is the case. The flatter the bar, or the larger the bar radius, the brighter will be the tone. The harder the bar and smaller the radius, the rounder and cleaner the tone. For the record, 1040 carbon steel (ie. a carbon alloy steel with 0.4% carbon) in a normalised condition has a nominal hardness of 170 on the Brinell hardness scale (about 3 on the Rockwell C scale - mild steel is softer), silver steel in it's annealed condition has a nominal hardness of 19 Rockwell C scale, while Roslau piano wire has a hardeness of around 45 Rockwell C. I can't imagine how bars made of the softer materials can stand up to piano wire, regardless of the counter bearing angle. But anyhow. . . . Regards, Ron O -- _________________________ Website: http://www.overspianos.com.au Email: mailto:ron@overspianos.com.au _________________________ --============_-1226355215==_ma============ An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/f7/37/94/ee/attachment.htm --============_-1226355215==_ma============-- ---------------------- multipart/related attachment A non-text attachment was scrubbed... Name: dmgdcapo.jpeg.jpg Type: image/jpeg Size: 25781 bytes Desc: not available Url : https://www.moypiano.com/ptg/pianotech.php/attachments/83/5e/61/de/dmgdcapo.jpeg.jpg ---------------------- multipart/related attachment--
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