[CAUT] pinned agraffe

[Ron Nossaman]

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