Backlit panel

cavelamb wrote:
Dan wrote:
Flash wrote:
"Orval Fairbairn" wrote in message
news_r_fairbairn-
If you wish to be more up-to-date, use red LEDs instead of the
grain-of-wheat bulbs. You CAN use clear plexiglass, with an inverted
bevel at the instrument holes. I would suggest painting both sides of
the plexiglass white, to contain the light, before the
cutting/engraving
operations. The front face can be left whit or painted in your desired
color.

--



Orval is on the right track.

But for best results, use clear plexiglas, coat both sides of it
white for better internal light transmission. Then, coat both sides
of it black, to stop extraneous light. Bevel or reverse-bevel the
edges,, depending on the effect yu require/desire. Engrave through
the top black /white layer into clear plexi. You CAN use white plexi
for this, but you will rquire so much more light (numbers of lights,
at many places) to achieve the illumination and readability at night
that you desire, as most white plexi absorbs a great deal of the
light - it just isn't as translucent as it seems, especially being
edge-lighted..

As for the "name-tag" material, the white inside in MOST oif that
stuff is opaque, and it is of such differing quality and material
from various manufacturers as to be a literal crap-shoot.

Flash


Maybe I have just had good luck with "name tag" material. As for
white plexiglass I never suggested opaque white although there are
varying degrees of translucence. Bear in mind any engraved plate used
for switches or similar don't have to be all that bright. It's all
relative to ambient lighting. An exception might be a panel that is
normally in shadow in daylight ops.

As for engraved plates there is one more idea. It's something I have
never tried myself. I have disassembled internally illuminated
military engine and pressure indicators. Many of them had 2 or more
328 sized lamps. The one inch round gauges had 2 lamps and the 2 inch
round engine/fuel etc had 2 or 3. What they had in common was a disc
thick enough to accept the lamp, the proper number of holes equally
spaced ina circle and a centre hole for the pointer shaft. The
instrument face was constructed one of two ways; either the face was
silk screened directly onto the aforementioned disc or another,
thinner disc.

The round indicator bodies are brass so if you want to see what I
mean see if you can find an inoperative one on which to perform an
autopsy. I used to get the 1 inch ones with burned out bulbs, but
working movements, just for the synchro inside.

Your suggestion for using clear plexiglass might work with silk
screened faces. I have never tried it since the plates I have made
were all one offs or so.

I have never used plexiglass instrument illumination so I have
nothing to say in the matter. A habit I picked up in the military is a
preference for internally illuminated indicators when possible. The
major drawback to that is the connectors for military instruments such
as clocks, g-meters and pitot-static instruments costs around $80.

I suggest anyone wanting to try anything along these lines should
obtain various plastics in various colours and thicknesses and haul
off and experiment.

Dan, U.S. Air Force, retired


Well, for what it's worth, I bought the boat today, so this project is a
go.

I think the annunciator question resolved itself as being impractical as I
had envisioned it. So it will probably just be a seperate panel with a
stack of back-lit blocks placed through the panel.

As for the rest; switch labels, panel legends, etc, I remember seeing
some translucent white in the scrap box at the Plastic Shoppe. I'll get
some
small pieces and of that and some clear Lexan and start experimenting
with them.

Thanks,


Richard

Good luck. Let us know what happens.

Dan, U.S. Air Force, retired