My First Agraffe Repair

[Carl Meyer]

Robert, sometimes the agraffes break because the threads are not up to the 
bottom of the brass.  A slight countersink in the plate will cure that. 
Chasing the threads is a good idea, too.  If another half turn is in order, 
It's good to tighten, then backoff repeatedly until you get the proper 
position.  It is less likely to break that way than if you bring it up to 
position in one fell swoop.  At least that is what I was told in a class.

I know the feeling when you tighten  them.  There are shims you could use 
too.

If you can use the old string that's a plus.
Carl Meyer PTG assoc
Santa Clara, Ca.

----- Original Message ----- 
From: "Robert Scott" <robert.scott@tunelab-world.com>
To: <pianotech@ptg.org>
Sent: Sunday, February 27, 2005 5:16 PM
Subject: My First Agraffe Repair


>
> There’s a 1927 Steinway M whose strings are a little rusty.  Even after 
> putting a drop of Protek where the strings go through the agraffe, one of 
> them broke off at the threads while I was lowering the pitch of G#2 (a 
> bichord).  So I guess I will be doing my first agraffe repair job.
>
> What worries me the most is how to decide whether to put one more 
> half-turn into the agraffe.  I don’t want to leave the agraffe too loose, 
> and I don’t want to tighten it so tight that I break it off.  Ideally, I 
> would like a torque spec so I could use a torque wrench to help me make 
> the decision.  If the agraffe is pointing in the right direction, but the 
> torque is less than X ft-lb, then I will go for another half-turn.  Can 
> anyone tell me what ft-lb limit I should use?  I guess most of you who do 
> this a lot develop a feel for how tight is enough, but I  need to get it 
> right the first time.
>
> In addition, I also wonder how one goes about centering the drill for the 
> easy-out on the remains of the old agraffe so that threads in the plate 
> are not damaged.  Should I expect to mess them up and just commit to going 
> up from the current 7/32" size to the 1/4" size agraffe by re-tapping the 
> plate?  And even if I don’t mess up the threads, it is usual to run a tap 
> through them anyway just to clean them up before the new agraffe is 
> installed?
>
> Finally, I managed to remove the old bass strings without cutting them by 
> straightening them just enough to slide through the old agraffe, so that 
> maybe I could re-use the old bass strings.  Is that a reasonable 
> expectation?
>
> Robert Scott
> Ypsilanti, Michigan
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