Re: Feasibility of machining harp plates

["Vern Smith" <jevern@xxxxxxx>]

- ----- Original Message ----- 
From: Pierre
To: harp-l@xxxxxxxxxx
Sent: Saturday, May 22, 2004 7:07 AM
Subject: Feasibility of machining harp plates

> I was at an Automation show in Montreal and that got me thinking, would it
be possible to machine plates > using the latest and greatest technology
available today?

> The ultimate goal would be to create a harp so tight it would be trivial
to set up for overblows.

The tolerances found in production reedplates are remarkably good already!
Any leakage from hole-to-hole or to the outside under the reedplates can be
attributed to some egregeous distortion and would not be improved by tighter
reedplate production tolerances.

The leakage through the reed-to-slot clearances is trivial compared to the
leakage through the gap of the opening reed.  Long, low-pitched reeds in
particular open more under the pressure applied to sound the closing reed.
This interaction is useful for bending.

If you want a particularly "tight" harp, just valve the reeds. This avoids
the leakage through the opening reed gap but shuts down the interaction
between reeds and changes the types of bends and overblows available. It is
fairly easy to add valves to a diatonic and see if you like the result. Talk
to Mike Curtis, a user of valved diatonics having great experience, about
the pros and cons.

Ease of bending or overblowing is affected most by gapping, not by
reed-to-slot tolerances.

Conclusion: In this case, there is no "free lunch."  Closer reedplate
tolerances will not materially improve harp performance. They would increase
costs dramatically. They would also make the reeds more subject to blockage
by small particles and make alignment much more difficult when replacing
reeds.

For all the above reasons, I am also skeptical about the benefits of
embossing, (reducing the reed-to-slot clearance by peening the edges of the
slots.)

Vern

Visit my harmonica website: www.hands-free-chromatic.7p.com