[CAUT] Hardness of termination vs string breakage (was Re: restrung D)

[Jim Busby]

Alan,

Spurlock used to sell a fret file and I spoke to him about the radius. I
can't remember the exact size but the Stewart MacDonald guitar parts has
a medium/large fret file which works out perfectly and is like what
Spurlock used to sell. 

www.stewmac.com/shop/Fretting_supplies/Shaping_and_crowning/2/Diamond_Fr
et_Files.html

They sell several types and grits but the courser grit seems to work
well followed with sanding. 2.5mm seems close to what it is. The company
couldn't tell me what the radius is. Don't get the cheaper metal file,
(trust me...) get the diamond one. 3 minutes or so with the fret file
then graduated passes with sandpaper to a buffed finish. When you can
run your fingernail down it w/o noticeable friction (i.e. smooth like
glass) you have the proper radius and surface. 15 - 20 minutes.

Regards,
Jim Busby 

-----Original Message-----
From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of
Alan McCoy
Sent: Monday, April 23, 2007 10:42 AM
To: College and University Technicians <caut at ptg.org>
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
>     -- 
>