what type of plastic is used for annunciator legends

[jonesthesoftware]

Does anyone know what type of plastic is used for annunciator/korry legends. It's black to look at until illuminated from behind then the legend shows up. I've checked with several plastic suppliers but they haven't a clue. I've used matt black over clear and engrave through the black with a diffuser behind but of course it doesn't match the originals.
I bought 1 korry switch from Open Cockpits as I had to find out what it was like and it's superb. I wish I could afford the 100 of these needed for a full cockpit!
geoff

[Westozy]

Hi Geoff,

The product I use is sourced from my local engraving supplies shop, it is 1.4mm thick and mostly clear. The underside is black and I estimate the black to be about 0.1mm of the total thickness. I engrave the black side to a depth of about 1.5mm in REVERSE! (I flip the text in VCarvepro before creating toolpaths). I use two 5mm LEDs in each annunciator and I paint the LEDs after fitting them to the backbox - yellow, red, green or whatever colour is needed. This method works quite well.
8686
Cheers Gwyn

[Avro748]

DIY Korry Switches (http://home.hccnet.nl/jwopdenakker/building%20tip.html)

I've heard that these work pretty well.

[jonesthesoftware]

Thanks for the replies guys. I've just demolished a real annunciator and this is how it's made....
Box painted white inside, 10mm thick cube of clear acrylic in front of each lamp, 2.0mm thick amber translucent acrylic with 0.7mm matt black/clear acrylic layer glued to it(black is the front). Can't separate the 2 acrylic layers but I assume it's the black one is engraved on the inside.
Best comparable results I can get is black translucent acrylic front over black/clear engraved layer but my black translucent is gloss finish not sure if it's available in matt but a coat of matt varnish gives excellent results.

regards
geoff

[John_B]

Hi I make my annunciators from 3mm white opal acrylic not being totally clear gives a nicer spread of light



8692

John