Re: [Harp-L] On Tolerances

["Tim Moyer" <wmharps@xxxxxxxxxxxxxxxxxxxx>]

I just want both you guys to know that at least one person (myself) 
is following this thread with fascination; please continue to 
digress as desired.  Let me add a couple of tidbits for 
consideration:  I generally consider embossing to mean the sides of 
the slots, not necessarily and certainly not exclusively the tip of 
the slot.  I have avoided the use of a ball for embossing because it 
doesn't move close enough to the tip, and I use a cylinder instead 
of a ball, so I can get it closer to the slot tip.  I don't 
generally emboss the reed tip.  

I agree that embossing doesn't imply a place where it is done, I'm 
just thinking of how discussions have transpired in the past.  

Please continue these discussions, I'm very interested to hear what 
you have to say!

-tim

Tim Moyer
Working Man's Harps
http://www.workingmansharps.com/

--- In harp-l-archives@xxxxxxxxxxxxxxx, Snaruhn@xxxx wrote:
Hi ron and Ludo,

OK, there´s a little point I have to correct myself when I assumed 
Ludo
had meant I would mix the reed with the slot.

< ..it is NOT working at the reedtip end ....>

I only recognized "reedtip" and not that the slot end = the end 
where the 
reedtip 
is was meant. My mistake! 

However, I stick to what I said about embossing just this part of 
the slot 
and
not its sides. 

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? However, once we are talking about the gap we 
should
examine the matter in toto.

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.

Important is also the tolerance of the reed sides or edges to the 
longitudinal 
slot walls. In the accordion production the extent of this tolerance 
makes 
the
difference between a quality accordion and an average instrument. 
The 
reedplates
of the latter are factory made, while the top plates are handmade.

Harp reedplates are basically not handmade but these tolerances are 
acceptable.
Not to forget: harps are mass products. That applies also to the 
harp 
Stradivaris:
Polle Concert Harmonica, Hohner`s Silver Concerto, BobDoug`s 
Renaissance.
They all have reedplates ex factory. 

An angry tolerance is occasionally a too big distance of the reed 
backside to 

the plate surface, exactly spoken, the reeds are curved convex 
(leackage!). 
The reason is obvious. The reed is rivetted ON the plate by a 
machine. By 
means of razor blades under reedtip and reedroot curved reeds can be 
bent 
cautiously below the plate surface.

However, the most angry tolerances are the "gaps". The different 
extents at 
the single reeds clearly show that we have to play on mass products. 
But 
these "holes" can be diminished by shifting the reed towards the tip 
(nothing for persons with two left hands), or giving any material to 
the slot 
end 
or embossing the plate at the slot end.

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.

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.

Ron, I hope that your offlist post is answered simultaneously.   

Siegfried




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