[pianotech] Agraffe threads out of spec

[Ron Overs]

Hello all,

We're currently at the assembly stage of a moderate overhaul of a 20 
year old US Steinway M. I didn't like the original agraffes with 
their oversize string holes, so I decided to replace them with new 
parts instead of re-cutting the original string holes.

The new agraffes have been here for a few weeks. I sourced them from 
a local parts supplier.

Today was intended to be the 'fitting agraffes' day, but it ended up 
as the 'return agraffes to supplier' day. Being a US piano, the 
agraffes threads are 1/4" by 36 threads per inch, but the parts 
supplied turned out to have a thread size of 6.5 mm OD by 0.75 mm 
pitch. Has anyone had this experience? The intended replacement parts 
(ie, the 6.5 mm things), instead of measuring around 0.246" across 
the thread OD when measured with a micrometer, actually measured 
right on 0.250", which is just around 6 thou smaller than their 6.5 
mm nominal size which would be 0.256".

Anyone out there have any ideas about a possible supplier of quality 
1/4" X 36 TPI agraffes, which are actually the intended thread size 
without oversize string holes?

Since our supplier ordered the parts as being 1/4" by 36 TPI, I'm 
wondering how many others  there are who have been caught with these 
out of spec parts. For the reference of others, these out of spec 
agraffes can be screwed into the plate holes about 3 - 4 turns before 
they tighten up due to the misalignment of the thread pitch.

Ron O.
-- 
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
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Web http://overspianos.com.au
mailto:ron at overspianos.com.au
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