cavelamb wrote:
Dan wrote:
cavelamb wrote:
Dan wrote:
cavelamb wrote:
Dan wrote:
cavelamb wrote:
I remember Linda Rice's Lockheed had a really cool backlit panel
overlay.
The panel itself was heavy aluminum sheet, but then they added a
plastic
overlay that had an opaque cover. Legends and labeling was done by
engraving the opaque layer.

On the back side of the there were little cavities carved for
grain of rice (well duh!) light bulbs.

The effect was quite stunning.

So does anybody know where to find this kind of plastic for the
overlay?


Thanks,

Richard


I use white plexiglass. Paint the face and edges black and have
it engraved or engrave it then use a roller to paint the face and
sides.

Dan, U.S. Air Force, retired


Ok, so other than good intentions and great karma, what kept the paint
out of the lettering?

If you paint it before engraving you won't have that problem.
Using a roller to paint after you engrave means very little, if any
paint gets into the lettering. I used a rubber roller like engravers
use. I prefer the paint first method, but sometimes you need to
repaint after adding engraving or damaged paint.

I might mention painting the back of the plastic prevents light
leaks.

For the truly patient/crazy you can route grooves in the back for
wiring. The number of lights required depends on the size of the
panel and embedded wiring means you only have 2 wires hanging out
the back.

Military/commercial lighted panels have a little coaxial connector
on the back that presses into a socket when you mount the panel. If
you ever see one of this type of panel you'll notice a little plus
sign on the front. The connector is directly behind it. Should
lighting fail you can press there to see if the connection is bad.
Older panels had light assemblies that screwed through the panel
from the front.

Dan, U.S. Air Force, retired

Thanks, Dan.
That's a possibility.

The comm shops in USAF units was authorized an engraver for
intercom boxes face plates since the boxes had a bunch of pull-on
volume controls and had to be re-labeled for the specific location on
the aircraft or specific aircraft. Guess what? They just swapped out
face plates when replacing the boxes.

Another option you might try is the black on white plastic
trophy/engraving shops use for name plates. Granted it's thinner than
the plates we used which were 3/8" thick or so. I suppose an
annunciator light or illuminated tail number plate can be made if you
make a bezel to hold it with the lamps behind.

You might also consider LED instead of incandescent.

Dan, U.S. Air Force, retired

Yeah, I remember fondly the side panels with all the cool military toys.
Boy, those were the days.

LED already considered. And approved, of course!

One design flaw so far is isolating some areas so that annunciators
don't bleed over into the rest of the panel.

I think that problem can be addressed by milling out the back plastic
but leaving an overlay but obviously won't work with a painted panel.

That's kinda why I was thinking of a thin plastic overlay.

The back-light panel can then be pieced together as needed but still
present a smooth unbroken surface.

I'm guessing something .008 to .016 thick(?) for readability of the
engraved parts.


With contrast the thickness is irrelevant in daylight. Think of name
tags and placards you have seen engraved on plastic. The clarity of the
engraving at night is more a function of line width and lettering size.

As far as annunciators I have taken aluminum, bakelite and plastic
blocks roughly 1/4" thicker than is needed for whatever lamp or LED
requires. Picture a square or rectangle a little bigger than the
annunciator with the center milled out to just under the size of the
legend. This allows the light to illuminate the back of the legend. I
then rabbit out inside a little deeper than the thickness of the legend
which can be glued in place. You can also make a block of annunciators
by this method using a bigger block of plastic with several holes milled
out.

For caution lights I have used red or orange plexiglass. I have the
legend engraved then paint in the letters in black. This is easier than
it sounds. I use model airplane paint, paint in the letters then
carefully wipe the excess off the face. For best results I use a thin
sheet of translucent plastic behind the legend. For the life of me I
can't recall what the plastic sheet is called, but I have bought it in
craft and office supply stores.

I have found the local glass supply here will only order coloured
plexiglass in full 4 x 8 foot sheets so I buy smaller sizes from e-bay.

Dan, U.S. Air Force, retired