Re: [Harp-L] On Tolerances

[Ludo Beckers <ludobeckers@xxxxxxxxxxx>]

Siegried wrote:
<< I stick to what I said about embossing just this part of the slot and not its sides. <<

Hi again Siegfried, I still disagree. This is how "embossing" is explained in brief on www.thenhole.com :

 A very effective modification is the narrowing of the slot (embossing). The reed slot is narrowed by pressing a round metal object along the sides of the slot, causing them to bend inward slightly.

A popular tool to use for this is the back of a tuning fork. The round ball at the end of the fork is placed on top of the reed and is moved along the reed while gently pressing down. This is delicate work and a few passes are usually required. 
Hold the plates up against the light to check the clearance between reed and slot.

If the reed gets stuck, check for rough edges either on the reed or the slot edges.
If the slot becomes to narrow it can easily be pushed back with the tip of a small screwdriver.

Narrowing the slot increases the overall responsiveness of the reed and reduces leakage when the reed is choked. The reduced leakage has a very big impact on overblow playing.



<<I think it´s necessary to clarify the understanding of the term "gap" before explaining my view point. We certainly agree that "gap" is the distance between reedtip and slot wall? <<

No, I don't agree. Gapping is altering the offset; the distance between reed and reedplate.

<< A fixed reed has 4 kinds of tolerances which are partly necessary partly can cause anger. The most important is of course the offset = the distance of the reedtip to the plate surface and is even crucial for starting the vibration.<<

Not sure what you mean by "anger" here. In your language I believe it means "böse".

<<Important is also the tolerance of the reed sides or edges to the longitudinal slot walls. <<

Exactly!

<< Note: It isn´t advisable to emboss the slot sides because the tolerance here is a fraction of a mm and one risks that the reed sticks.<<

If the embossing is done overzealously, the sticking reed can easily be freed with a feeler gauge. 

<<Well, Ludo, the term "embossing" doesn´t point to the spot where the embossing is performed, it´s just a kind of working a metal surface, no more no less.<<

I agree, but applied in harmonica jargon I believe we still misunderstand one another here :-)

Ludo


		
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