Posted by: "werainey"
> We're interested in testing a conical reflector for long term logging of =
bat acoustic activity
> (frequency range roughly 4-100 kHz). It seems that mounting the micropho=
ne in a shallow
> shroud with a drip edge facing vertically downward over a coaxial 22.5 de=
gree cone (apex up)
> would overcome some of the icing and other inclement weather problems we'=
ve encountered
> with simpler planar reflectors in past years.
>
> Assuming this seems plausible, I'd welcome suggestions for an affordable =
source of smooth,
> sharply pointed, closed cones of relatively tough, lightweight, weather r=
esistant material
> (spun sheet aluminum, polycarbonate?). Web searching typical leads to con=
es with a aperture
> at the apex which we don't want.
How big a cone do you need? They could be cut on a metal lathe. Or cut a
prototype on the lathe and use it to make a mold for production. The
size of lathe needed goes up fairly rapidly as the base diameter
increases. Delrin would be a good material for small ones, or at least
it's what I'd try first as I have a supply. It's possible it might flex
too much for getting a fine point, however. 6061 alloy aluminum is
pretty weather resistant and fairly easy to machine.
Hard to spin aluminum to a point. But you could come up with a cone with
a aperture and then use a lathe cut point in that.
Walt
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