[CAUT] pinned agraffe

[Bob Hohf]

Unless we can ask the designer (who may still be around somewhere), the
actual intent is anyone's guess.  My guess, FWIW, is that the strings are
not intended to bear on the steel pin, but the pin is installed to reinforce
the brass in some way.  Does the pin really make the agraffe more rigid?
Who knows?  

However, the fact remains that the pin is exposed in the holes of some
agraffes and not others.  So no matter how you take the intent, a whole
bunch of them are defective.  But they sure look cool.

Bob Hohf



> -----Original Message-----
> From: caut-bounces at ptg.org [mailto:caut-bounces at ptg.org] On Behalf Of Ron
> Nossaman
> Sent: Monday, November 15, 2010 10:30 PM
> To: caut at ptg.org
> Subject: Re: [CAUT] pinned agraffe
> 
> On 11/15/2010 7:20 PM, Bob Hohf wrote:
> > It seems to me that this discussion is missing the intention behind
> > pinned agraffes. If terminating the vibrating string with steel were the
> > intent, wouldn't it be simpler to make the whole thing out of steel? And
> > wouldn't a steel termination defeat the purpose of using brass in
> > agraffes, since brass is "lubricious" in contact with steel strings?
> 
> So the intent being missed is?
> 
> 
> >I bought a set of pinned agraffes from Renner Stuttgart that I intended
> to
> > use to replace solid brass ones in a Bosendorfer I was rebuilding. After
> > close inspection of the pinned ones, I decided to re-install the
> > originals. In most of the pinned agraffes I have, the steel pin does not
> > make the termination, but appears to be backing up or reinforcing the
> > relatively soft brass.
> 
> Meaning what? Is the string bearing on the brass, or the steel? Or is it
> random?
> 
> 
> >However, in a number of them, the steel pin has
> > broken through the brass creating some nasty-looking brass burrs that
> > would be sure to buzz on the string. My take is that the pinned agraffes
> > are a good idea that but are too difficult to manufacture with enough
> > consistency.
> 
> I've wondered about this for some time. As you've noted, the tolerances
> required shoot the intent in the foot. Drilling the agraffe so the
> insert is precisely tangent to the hole in the brass is unlikely at
> best. If the brass is in contact with the string, the steel rod is
> superfluous. If the string is terminating on the steel rod, it's most
> likely on a horizontal surface where it could be some distance left or
> right of top dead center of the hole in the agraffe, where it would be
> inevitably top dead center in a brass or steel agraffe. How is this any
> different from a capo? And how does this translate into getting the
> trichord dampers to seat when the string spacing isn't corralled by the
> agraffe hole? I know, trichord damper cut precision too often sucks, but
> a wide possible unison string spacing within the agraffe can't improve
> that situation a bit. So what's the benefit, and why do I keep hearing
> about these pinned agraffes as if they are a good thing?
> Ron N