[Harp-L] Slot Embossing and Accordions

[Rick Epping <rickepping@xxxxxxxxx>]

When I first started describing reed slot embossing to harmonica customizers
and on harp-l in the mid 1990s I said it was a technique used by accordion
reed makers.  This statement was based on information from Delio Gabbinelli,
an Italian accordion technician I worked with in New York from 1982 to 1984.
I had described to him the embossing technique I developed while working on
an experimental accordion reed and later applied to harmonicas, and he said
it was like a procedure reed makers sometimes employed to obtain a close
reed-to-slot tolerance.  But he did not demonstrate this technique to me.

Since then I have worked on hundreds of accordions, mostly Italian and
German but also French, Russian, Swiss, Czech, Chinese and Swedish
(thousands of accordions if all the Hohners I've serviced are included) and
I have never seen an accordion reed with an embossed reed slot.  Upon
reflection I have come to the conclusion that the technique mentioned by the
accordion tuner was very likely not slot embossing but one where an area
around, but recessed from the slot edge is coined or otherwise depressed in
order to force the adjacent slot side in closer to the reed.  I have seen
some old Hohner accordion reeds modified in this manner and posted a photo
of one, along with that first reed I embossed at:
https://docs.google.com/Doc?docid=0AZ6Y28n7JwtSZGNra24yZDZfMThjY24zbnhocw&hl=en


The main problem I can see in employing slot embossing on accordion reeds is
that embossing effectively lowers the slot edge into the reed slot, creating
a vertical gap between the reed and slot which requires the reed to be
recessed into the slot at the rivet pad in order to compensate.  This is
easy enough to do with harmonica reeds; factory workers sometimes use their
fingernail to lower the reed at the rivet pad when adjusting newly riveted
reeds and this how I adjust reeds after embossing.  Accordion reeds are
thicker and much harder, being made of blue steel, and cannot easily be
adjusted in this manner.  Coining an area of the reed plate offset from the
reed slot can achieve similar results to embossing without lowering the reed
slot edge.  I've attempted coining harmonica reed plates but found that they
can become deformed enough to cause air leakage between the reed plate and
comb.  Accordion reed plates are thicker and less likely to deform after
coining and, anyway, are set onto their reed blocks with wax so that any
irregularities or gaps between are filled.  However, I doubt that any
technique like this was ever very widespread as I only ever saw it on a few
old Hohner accordions, made during the period that the Italian master
accordion maker Giovanni Gola was in charge of Hohner's accordion
production.  My guess is that this was a technique that Gola had used in the
past and for a period incorporated into Hohner accordion production.
 Accordion reed slots, even for high-quality handmade reeds, are stamped out
on heavy presses.  After stamping, enough of the surface of the reed plate
is then milled away to eliminate any material deformation around the tool
entry area and create an even, sharp slot edge.

Rick