Hi Ted, Pardon my thick-headedness. If a #40 drill has a .097" diameter, wouldn't that mean that it has a radius of .0485". If you like a capo with a radius of (2.5mm or ) .098", wouldn't a #9 drill that has a diameter of .195" (r=.0975"), then be a better visual reference for a radius of .098"? Am I missing something, or when is a radius not a radius? Alan > From: Ted Sambell <edward.sambell at sympatico.ca> > Reply-To: "College and University Technicians <caut at ptg.org>" <caut at ptg.org> > Date: Mon, 23 Apr 2007 14:21:19 -0400 > To: "College and University Technicians <caut at ptg.org>" <caut at ptg.org> > Subject: Re: [CAUT] Hardness of termination vs string breakage (was Re: > restrung D) > > > Alan, you are close enough. 2.5mm converts to .098" Agraffes are generally > close to this too. A #40 twist drill has a diameter of .097, which will give > a good visual idea of the radius. One thousanth of an inch or so is > certainly a permissible tolerence > > Ted Sambell > > > ----- Original Message ----- > From: "Alan McCoy" <amccoy at mail.ewu.edu> > To: <caut at ptg.org> > Sent: Monday, April 23, 2007 12:41 PM > Subject: Re: [CAUT] Hardness of termination vs string breakage (was Re: > restrung D) > > >> Ric, >> >> Would you mind quantifying "thin" and "sharp" for me? Ted Sambell talked >> about a 2.5mm radius, which works out to 0.1" or between a sixteenth and >> an >> eighth inch radius (for metric-phobes). >> >> Thanks. >> >> Alan >> >> >> -- Alan McCoy, RPT >> Eastern Washington University >> amccoy at mail.ewu.edu >> 509-359-4627 >> >> >>> From: RicB <ricb at pianostemmer.no> >>> Reply-To: "College and University Technicians <caut at ptg.org>" >>> <caut at ptg.org> >>> Date: Fri, 20 Apr 2007 23:46:46 +0100 >>> To: <caut at ptg.org> >>> Subject: [CAUT] Hardness of termination vs string breakage (was Re: >>> restrung >>> D) >>> >>> 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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