Multiple plates per panel

[birdyguy]

Hello everyone,

Silly question here, but why are there two to three plates for each panel. I'm building my own panels for overhead and I've noticed some panels are sold with three plates of plexi and not sure why this is. For the lighting area of the overhead for instance..there is the main colored plate, then a clear plate of the same size and then a white plate of the same size.

I'm thinking that the clear plates are most likely used for mounting standoff switches. The third white plate not really sure what it's purpose is. Would appreciate if someone could shed some more light on this for me.

[tiburon]

I think it might be because the real thing is about 6mm thick without the mounting plate. So there's a aluminium plate (the clear plate I'd say) for mounting all the hardware and a lightplate (white) to diffuse the backlighting. So you just have to paint the sides of the plates to get a reasonable thickness.
Does that make sense ?

[birdyguy]

Hi tburon,

Yes , that makes sense. Thanks.

[Westozy]

How I build my backlight panels! The top "lightplate" panels are made from 3mm white acrylic, this gets painted in the appropriate RAL colour then the panels are engraved through the paint. The light from white LEDs penetrates the 3mm white acrylic for a good result. The second layer panel is cut from 3mm clear acrylic and this is used to mount the switch hardware and these plates have their edges painted. If the panels were machined from a single piece of 6mm acrylic the backlighting is dull and not to good at all. This is how most vendors are doing it these days if the panels aren't IBL.

Sim rebuild 058.jpg
Cheers Gwyn

[birdyguy]

Thanks Gwyn. Very informative. I don't have access to an to an engraver so what I'm doing is printing out the overhead bitmaps that you sent me long ago (thanks much again) , then peel off the backs of the printouts and stick them to the acrylic . I then spray them half dozen times with clear coat. Seems to work quite nicely for now.

So my understanding from reading the above comments, two plates should be plenty.

[tiburon]

What's IBL ?

[jonesthesoftware]

I'd just like to add that you need to select white acrylic NOT Opal as Opal gives grey characters when not backlit. 3mm White acrylic comes in 2 grades of light transmission, approx 4% and approx 16-20%. Make sure you tell your supplier you want the 16% variety. IBL is internally back light.
regard
geoff

[fordgt40]

Another way with better results, albeit more "tricky", is to use clear acrylic which you then spray white after it has been cut to shape. Then subsequent top coats can be applied. The tricky bit is setting the laser to cut through the top coats but not the white base coat
The benefit of this approach is more even lighting as the white initial coat traps the light inside and gives a better spread, also, the white engraved letters stand out better. I have not tried this method, but it was outlined to me by one of the "best" private panel makers

[RadarBob]

The way fordgt40 has described is pretty much how the original light plates are done.

I rubbed back some of the paint layers on a broken original to find out.

On the one I looked at, there was a large depth of matt white, followed by a matt black blocker layer and then the top colour.

I tried making my own copy using 6mm clear acrylic, machining out the back to
accept very small white leds (instead of the filament lamps) mounted on a pcb.

The back of the acrylic is also painted (white) and the technique relies on introducing the light in the centre of the acrylic between the layers and creating a spread.

I was quite pleased with the results, but I found:

There is a lot of careful machining involved with drilling blind holes in the acrylic
-The large recesses around switches and knobs are particularly tricky.
- I used all sorts: End Mills, Forstner bits, Mad bits etc to do it - One slip and you've had it!

It's very slow going - Lots of paint coats and waiting.

If you use rattle cans, it cost a fortune.

The paint needs to be well cured before you try to engrave it otherwise it tends to tear and look a bit ragged - Don't know what paint they use but it is very hard anyway.

You need a good sharp engraving tool

Some white paints look a bit yellow even with a white led.

If you use leds mounted horizontally you need to work out their positions carefully and angle them towards the area in which you want the light to spread - You also need to keep the distance from the text to the leds fairly consistent or the lighting is overly uneven.

Was an interesting experiment, but I decided that it wasn't practical.

Best Regards,

Rob

[fordgt40]

Rob

Very informative, thanks. Perhaps this method has too much grief and risk attached

David