[pianotech] agraffe replacement

[Ron Nossaman]

On 7/18/2011 2:38 PM, Alan Eder wrote:
> I last got agraffes of the crushable perimeter type--and a counterbore
> for reduction of height upon contact with the plate--from Pianotek.

I get mine from Pianotek too.


>One
> caveat: there remains the possibility that the holes in the agraffes are
> not an absolutely uniform distance below the part (the top) that I am
> measuring. Have not yet found a worthwhile way to reign in that
> potential variable.

You index height across the tops of the strings instead of the tops of 
the agraffes, and you're covered either way.


> P. S. I highly recommend getting a few extra agraffes and conducting a
> couple minutes worth of valuable research that will guide you in your
> work. Tighten one down to when it contacts the plate, then keep going,
> paying careful attention to the sound it makes and how it feels.
> Continue until it breaks, and calibrate your operation accordingly.

  I'd say get a few extra of the crushable perimeter type so you can 
find one that snugs up about 60° short of perpendicular to the string. 
Then crank it down. We've seen many agraffes that were overstressed in 
installation that didn't break at the time, but did so much later, so in 
this case, I'd not recommend the force to breakage, then back off 
calibration method. It is, however, a good learning tool in a number of 
other situations, and I've made extensive use of it - intentionally and 
otherwise.

Ron N