Re: [Harp-L] Reed Slot Tolerance

[joe leone <3n037@xxxxxxxxxxx>]

On Dec 3, 2009, at 12:50 PM, Robert Coble wrote:

> I know I have seen several references to using a 0.001" shim to run  
> down the sides of a reed to make sure there are no burrs on the  
> edge and also that the reed is seated in the middle of the slot.

The use of the shim is to clear any debris (saliva, etc) and to check  
and see if the reed is centered enough that the shim goes down the  
slot evenly on both sides. If it is tight on one side or better still  
near the tip, this means that the reed needs to be 'walked' into the  
center. This can be done with a reed wrench. But I prefer to tap the  
reed about 2/3rds the way from the rivet with a sewing machine needle  
with the eye broken so as to give a V notch at the tip in order to  
engage the reed.
> Would this not imply that the normal clearance/tolerance between  
> reed edge and reedplate edge is 0.001"?

Give or take, yes. Cheaper harps have larger tolerances. This is not  
necessarily a bad thing as it works good for firearms. But when  
accuracy is needed required wanted or you have the money, closer  
tolerances are desirable and while I never actually studied this  
tolerance thing, I would imagine by logical imaginement that looser  
tolerances might have an affect on the sound produced by a reed.  
Hence embossing.

> If so, then the manufacturing tolerance obviously is not impossible  
> to obtain with hobbyist-level tools,

You are correct. Hobbyist level tools are finer than the general  
level of tools available when people were first making harps in 1835.  
If they could do it then, for sure we can do it today. Just look at  
the fabulous cloisonne and lost wax work that the French did in the  
16 and 17oos.

> which have at least that capability (on paper, if not in fact). If  
> the tolerance is smaller, then wouldn't using a 0.001" shim cause  
> some sort of misalignment or deformation?

No not relly, the shim is rather flexible and WILL deform as it is  
really only thick foil. Although stainless steel, it is much thinner  
than the brass and doesn't have the bulk to do damage on any but the  
very thinnest high pitched reeds. Needless to say, if a body is ham  
fisted, NO delicate tool will make a difference. A person has to work  
with their hands to get a feel for ..well..working with their hands.  
I mean, I have been known to crawl under my 1968 charger daytona and  
beat on the starter motor with a pair of vice grips till the solenoid  
re-set. At other times, I have inserted screws in eyeglasses or  
watches. It's all in the hands.
> My tool of choice for deburring the edges of reeds in the slot is  
> to use one of those little magnetic security strips. I owe my  
> introduction to that tool source to Mr. Bill Price, who is always a  
> joy to be around at the VA Harmonica Fest, regardless of whether  
> he's playing some instrument (he's multi-instrument talented) or  
> working on making a harmonica work better.

I was just WITH Bill for a day at the Garden tate fest. I didn't have  
my tools, so I used his. The device comes encapsulating 3 strips. The  
best way to retrieve the FLAT strip (the other 2 are vaulted), is to  
cut the plastic carrier close to the strip but without touching it.  
Then soak it the rest of the way in acetone to release the gummy  
gooey matrix that it is swimming in. That way you don't damage the  
strip.
> Help, please,
> Crazy Bob 		 	   		
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