String breakage at the capo is more complicated then just one bit. I have a 9 foot Petrof under my care with the same feature (actually a pretty good one in my book as well...) The <<soft>> capo sharpened will indeed groove over time... but if other issues such as speaking length of the string and counterbearing angle are compatible with the soft, sharp capo... then whatever trouble you have with string breakage must find its roots elsewhere. I havent seen a broken string on this Petrof (strangely enough) for over 18 months except in the bass and agraffe sections... and its played hard 6 days a week 10 months of the year. Three quarter medium strike weights for what thats worth. Each instrument is different to be sure, but by and large most whose experiences I have listened to through the years have reported fairly consisitently that thin, sharp, and soft works much better over time then wide round and soft. Again... I suggest reading McMorrow for some interesting perspectives on exactly this subject matter. I agree tho... the proof is in the pudding. I've been handling capos as mentioned in earlier posts for well 25 years now... and have had ample opportunity and more to watch the results over time. Petrofs and Bosies are not, definitely not proverbial high treble string breakers. God knows Petrofs have problems they need working out... but this is not one of them. Not in my experience anyways. Cheers RicB With all due respect. I had an experience several years ago with a Bosendorfer grand which seems to contradict this. It continually broke strings in the top section. Bosendorfer, and I believe Petrof have retained a feature found in early 19th. century pianos such as Streicher and Erard, namely, a removable treble capo bar. I removed this and found it to have a very sharp edge, and to be badly grooved, the edges of the grooves still as sharp as the unworn arears. The metal was quite soft , so I was able to easily reshape it to the radius resembling that of a 2.5mm rod, and polish it. I then re-strung the section (actually the two top sections) and there has never been a broken string since over many years. The piano is used quite heavily by good pianists. Moreover, if anything, the tone was better than before. A vibrating string is quite evidently being stretched at amplitude . and the consequent lengthening is offset by the alternating termination point caused by the deflection of the wire around the radius of the bar. As is said, the proof of the pudding is in the eating. Ted Sambell---- Original Message ----- From: "RicB" <ricb at pianostemmer.no> To: <caut at ptg.org> Sent: Thursday, April 19, 2007 3:00 AM Subject: [CAUT] Hardness of termination vs string breakage (was Re: restrung D) > > It is a matter of all these things, including hardness. Really, this kind > of goes without saying. A soft sharp profile will wear and groove, and it > will do so in a way that works out nicely over time. A rounded soft > profile on the other hand will buzz like crazy with wear. Dig out > McMorrows book for some good perspectives on it. > > Fred, there is friction at the bridge pin from something... this is > obvious because of the pins getting damaged over time. If the metal of the > pin was significantly harder then the string... these same moments would > still be at work and the wear and tear would be transfered to the string > material. > I mean... why would we have any use for super hard abrasives like diamond > files or any such thing unless the basic idea that harder vs softer > results in softer loosing ? > > Cheers > RicB --
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