[pianotech] Managing agraffes was Increasing bridge height

[CHARLES BECKER]

my broken agraffes  studs have all been in Steinways from the 20's. Are 
these the agraffes Ron is describing?
----- Original Message ----- 
From: "Ron Nossaman" <rnossaman at cox.net>
To: <pianotech at ptg.org>
Sent: Wednesday, March 25, 2009 11:21 AM
Subject: Re: [pianotech] Managing agraffes was Increasing bridge height


> Jude Reveley/Absolute Piano wrote:
>
>> 
>
> Exactly!
>
>
>> In the case of these particularly nasty string height sections, what are 
>> our options?
>
> Fix what you can, within your self imposed tolerances, and compensate for 
> what you can't fix within your self imposed limits of time and money. Each 
> individual approach to each individual job will have it's own distinct 
> personality.
>
>
>> Although somewhat unsightly, what about adding washers or dressing the 
>> bottom of the agraffes' base?
>
> Why not? Manufacturers did/do.
>
>
>> Do you feel it necessary to tighten the agraffes down. When is too tight? 
>> Any torque specifications.
>
> I tighten them. No torque specs, but something under 45° from finger snug 
> to square and seated.
>
>
>> One idea I've been messing with is not going so tight and using a bit of 
>> thread lock. As I understand the strength of threaded bolts, full 
>> strength is reached before a bolt is fully cinched down anyway. I'll try 
>> to get some torque measurements of what I mean.
>>  Comments appreciated...
>>  Jude Reveley, RPT
>
> The (thankfully few) instances of broken agraffe studs I see are usually 
> the flat bottomed shoulder with the threads stopping short. The agraffe 
> was either forced down past where the threads were actually cut, or not 
> quite seated at all, or both. Or they were seated and just cranked too far 
> past snug on a shoulder that didn't deform to meet them half way. Modern 
> agraffes with the undercut shoulder are much more forgiving.
> Ron N
>
>