Re: Feasibility of machining harp plates

["Vern Smith" <jevern@xxxxxxx>]

- ----- Original Message ----- 
From: "MLeFree" <mlefree@xxxxxxxxxxxxxxxxxxxxxx>
To: <harp-l@xxxxxxxxxx>
Sent: Saturday, May 22, 2004 12:16 PM
Subject: Re: Feasibility of machining harp plates


> I know that Suzuki tunes their reeds with a laser.  This makes me wonder
> about using a high-power laser cutter to cut reeds and reed plates.  You
> can't achieve better machining accuracy, so I would expect a laser-made
harp
> to be as tight as mechanically feasible.

It is very difficult to hold tolerances to less than .001" with square-edged
and straight-sided holes in .040" thick plate material with laser cutting.
It works for the holes in a slide because there is no other part that mates
precisely with the laser-cut surface and the tolerances may be much looser.
The old punching process is hard to improve on for accuracy, surface finish
on the hole sides, and economy.  A punch goes "bang" and produces a whole
plate in a fraction of a second! The punches and dies eventually wear out
and the quality of the plates deteriorates as they do.  However, if the
tooling is kept in good condition and replaced when needed, there is no need
to change.

Wire EDM has the capability required for reed slots. Its only advantage
might be if you wanted flexibility to make only one or a few plates or
wanted to change the design often, and thus wanted to avoid the cost of the
punches and dies.

> OTOH, I betchya Vern Smith has one in his garage...  8^)

The only thing that I have that wouldn't be found in anyone's garage is a
little Sherline table-top milling machine.  I have never been there but I'll
bet that either Bill Romel or Joe Picirilli has the best equipped shop.

Even the most expensive custom harps use plates and reeds punched by Hohner.
Tighter tolerances in the slides of chromatics can minimize hole-to-hole
leakage but there isn't much that you can do in the way of tighter
tolerances to improve a diatonic.

Vern

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