Re: [Harp-L] Slot Embossing and Accordions




On Jan 30, 2010, at 7:20 AM, Rick Epping wrote:


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.
That's when 'I' first found out about it.

This statement was based on information from Delio Gabbinelli,
an Italian accordion technician I worked with in New York from 1982 to 1984.

I got my 'baptismal' from Ernesto Contente. A bandoneion player from Burnos Aires. (Italian decent)


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)

Well then, I would call you 'the' authority on the subject. That's a LOT of boxes.


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:

On the one hand you say you never saw a case of embossing then you say that you have seen some old Hohner reeds modified in (this?) manner.
I think you lost me.


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,

Doesn't all embossing do this? This is why I say to use a large dia embossing tool. As I said last night, you DON't want to 'furrow' (which is what you're talking about (I think?). You want to 'swage'. You want to gradually force some of the soft brass (or in the case of accordions..mostly aluminum) in towards the reed edges.


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.

Why would you have to DO that. A reed is already raised above the slot. Embossing only slightly changes this reed to slot edge height. Then the reed can be re gapped if necessary And it usually isn't necessary.


This is
easy enough to do with harmonica reeds;

I would think just opposite. ANY change on a harp reed would have an influence on the action. People have a normal breath of 275ml. At rest maybe 80ml, sleeping maybe 25ml. A concertina starts with a volume of 900-950ml , a Cajun diatonic accordion about 3 litre and a medium 27 key around 10 litre, and if you pull the bellows full out on a 41 key concert model, we're talking 35 litres. (about 140X human).


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.

Ok, I see where you're coming from. This is where 'drifting' could come into play.


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.

Yeah, and it's a LOT of work. Ain't worth the trouble. 2 things. Accordion reeds are usually DOUBLE riveted. Hold them up to the light and you notice that they are very well centered. And nothing, save being deformed in some way will knock them OFF center. The tolerance (s) are as high as .0040.
A harmonica reed almost NEVER sits in it's slot evenly with the same light showing through from both sides. They are usually on some sort of an angle where the rivet end is close on one side and the tip is nearly touching the other side. That IS a problem because the tolerances average .0012. With differences ranging from: jammed reed...all the way up to .0018. Soooo, if you emboss and you emboss EVENLY, you're wasting your time because you're working on a reed that wasn't even in the first place.


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.

Might have been a practice that the Italians were familiar with. I'll make some phone calls.


Accordion reed slots, even for high-quality handmade reeds, are stamped out
on heavy presses.

Yes, they are about 1/8" (or more) thick.


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.

Yes, I wrote about this years ago when I wished that premium harmonica reed plates were made this way. After the punch presses through, the EXIT side can be stropped, while the ENTRY side should be taken down via slurry honing to remove the 'rounded' entry shoulder. I know, I know, there should BE no entry shoulder, but I suspect that dies aren't changed as often as they could be and begin to loose their shearing integrity after a run of units.


For example, In a 1000 unit batch, the first 800 will be fine, the next 100 will be marginally passable, the next 50 will be 'blems' and the last 50 will be junk.

Just a few thoughts from my poor old gourde..... Jose Dos Equis




Rick _______________________________________________ Harp-L is sponsored by SPAH, http://www.spah.org Harp-L@xxxxxxxxxx http://harp-l.org/mailman/listinfo/harp-l




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