Has anyone got any top tips for making backlit panels? I’m working on a project now but I’m not sure if it will be as effective as I want.
I have a couple of throttles from Throttletek which have back lighting, and the way they do is to make the panels (in fact, the whole structure of the throttle) in clear acrylic and then paint it and (I presume) laser-etch text into it. From having scratched one of the panels (in a part I’m getting rid of) I can see that it’s clear acrylic, with a white undercoat, and then the final colour sprayed on top of that. The lettering is white where the undercoat has been exposed with the laser. Then they have dug out small pits in the back of the panel and placed micro-LEDs inside the pits, so they shine light through the material as a light pipe. This seems to work quite well; you require several LEDs per panel but that’s not a big deal.
(I can’t post picture of this as Throttletek require you not to in their T&C - I think they don’t want their control mechanisms getting out to competitors, which is fair enough.)
I don’t have the capability to laser-etch lettering into panels and I’m not about to buy a laser cutter just for that, so I’m planning to follow the Throttletek method in terms of a white base coat, black top coat (but not on the front face which will remain white), and use embedded LEDs for the lighting; but then use the ‘laser transparency’ method on top of that: basically, print a 1:1 image of the panel in black & white on self-adhesive laser transparency paper, layer it two or three times, and stick it to the white-painted front of the panel. The idea being that the lighting shows through the white (which prints transparent) areas on the print, and the black blocks light from elsewhere. And then I put a final layer which is printed on regular thin self-adhesive paper stock, which is full colour with text in white, and the light shines through that. Then you put lacquer on top of that to seal it all.
I’m aware that there are many ways to skin a cat so I wanted to ask this community if there are any backlit panel builders out there, and if so, how you’ve done it.
From what I understand (I’m not an optics expert <g>) to use a diffuse material you need a strong back light source across the whole panel, rather than one or more point sources. The goal (for me) is to increase the internal reflection to as close to total as I can get on all faces except the front so it basically becomes a light pipe. I tested this, and when the panel is painted in smooth white and you dig out a pit in the back and put a light source directly in there, you get lighting through the whole volume although it becomes less intense the further from the light source (and there’s a hot-spot where the light source is - I might try a dot of white or black paint in the very top of the pit dome to try to get the light to spread horizontally).
But if anyone has examples of panels made with opal acrylic (translucent), I’d be keen to see them!
Small backlight test I did with a green led strip…
Put together 2 white panels and the one on top was painted in black and in some I used CNC and others were laser etched. Doesn’t matter, the results were great in both methods.
If you have patience then you can get great results with sticky letters on white acrylic cut to the individual module size you want .I found that opal acrylic as the background 'white ’ was too hard to see.Then spray with aerosol your chosen colour and when dry remove letters and voila.I used a snake of leds for the backlighting.
I have made my own backlit panels for my 737 cockpit. The approach I selected was to start with opal acrylic, which diffuses the light better internally than clear acrylic. I have a CNC router, so the shape was machined, including a pocket on the backside for the backlight PCB. The panel was then painted first with several layers of white. Then a couple of layers of black to prevent shine through, and then a couple of top layers of RAL7011. After drying the paint I pocketed space for the SMD LED diodes and engraved the text on the front. The down side of this approach is that the letters are opale and not white then the backlight is off. And engraving on something that is not totaly flatt is finicky.
So, for context, here’s an old panel from my Throttletek unit, made of clear acrylic with white undercoat and Airbus blue topcoat. You can see where I’ve scratched the paint off to look at how it was done underneath. I covered some hotspots with electrical tape and then put a micro-LED into the pit at the back on the left and turned it on; it’s rather overexposed (thanks iPhone) so it’s not as bright as that in real life but you can see how the lettering on the left side lights nicely, and you can see the light shining through the uncovered areas as the acrylic is acting like a light pipe.
The photo of my Cockpit is as you can see a very poor shot indeed ,but when in the cockpit the overhead panel and a few other panels I made which are out of shot do light up pretty well in daylight and obviously more so at night, so I do not feel that a base white paint is absolutely required to do the job for a home use cockpit as long as you get the right white acrylic sheet.
Lots of great ideas in this thread. Keep them coming!
I have already had parts laser-cut in clear acrylic, so I basically have to use that or go back to the CAD place for more cuts (which I will do if I need to, but it’ll take a week or so to get the pieces). Right now I’m trying a couple of coats of flat matt white all over, then coat the back and sides with matt black, mask off the areas on the front where text is shown, and then spray the front black too. That concentrates the light emitted to just the white areas still on the front panel. Then I’m laying down multiple layers of transparency with a black background / transparent lettering pattern on it (you seem to need 2 or 3 to block the stray light) and then I’ll put a full-colour copy of the panel design on top of all of that. My tests so far indicate this will probably be adequate for my needs - which are only to have illumination in the dark, which I rarely fly in anyway. I want to reach parity with the backlighting on my Throttletek panels if possible.
Challenges are getting the paint coats even - it might look even but with light behind it suddenly you see where it’s not quite so well-covered - without blocking off too much light to get a good effect through the label on the top. Also, getting the multiple layers precisely aligned is hard. I’m using registration marks on the print to do this.
Due to mistakes, I’m now on the third copy of one panel part, out of four that I ordered in order to have some spares, so if I muck this one up, I have one chance left!
I think I may order some slightly larger micro-LEDs. The ones I have are very bright but very small and it’s too much of a bright pinpoint light.
I use 2-layer plastic by Rowmark. black on white. Laser through the black. Light shines through the translucent white. Then spray on a coat of matte picture protectant from Michael’s to eliminate scratching. Works great.
Interesting. I had a look at their range. Of course, it isn’t much use to me without a laser engraver. So I bought one
Basically, I tried two different methods and I wasn’t happy with either of them, so I decided to just bite the bullet and buy the kit I need to do it properly.
I’m looking to match the existing back-lit panels from my Throttletek kit which are painted in Airbus blue, specifically the older style RAL Pigeon Blue. Got some spray paint mixed to the RAL code, and my plan is to laser-cut then paint white opal acrylic and then engrave the text through the paint layer. Thankfully there’s plenty of YouTube content to help me there.
This is opal acrylic with a top layer made from mountboard and lettering laser-cut out of it so light shows through from behind the acrylic. I would be using LEDs in actual use but holding it up in front of a diffuse light source lights it up evenly and quite nicely. I would still have to put on a laser-printed top layer in the final colours.
There are drawbacks with this method, though. I had to add stems to the letter shapes to stop the ‘holes’ in the middle of letters dropping out when cut, which creates a stencil-like effect that does show through in the back-lighting. And because the mountboard layer is 1.4mm (the thinnest I could get from the laser cutting place I used) there’s a 3D effect where viewed from an oblique angle the back-lighting is obstructed.
This made me realise that if I was going to do this, I had to do it properly, and now that I know what a laser can do I realise it’s going to have many applications in my cockpit project going forward. So I don’t regret the investment, but there’s a steep learning curve. I’ll post picture of my progress in the main cockpits thread.
Could you please tell the name of spray used ? I am working on airbus a320 sim and the problem im facing is that the panels are too translucent and the backlighting led make a ‘glow spot’ around the lettering. I just want the lettering to be illuminated. Also the panels are to be colored gray ( as that on airbus cockpits) as opposed to black.
However, for my laser-engraved panels (which I’m still in the process of setting up to make) I intend to use thin opaque white acrylic (1 or 2mm) with a backing of frosted clear acrylic as a diffusing layer, and then spray paint the surface with probably 4 coats of acrylic paint. Then I will laser-engrave through the paint to expose the white acrylic which will be lit from behind by strong lighting diffused by the frosted acrylic layer.
You need enough paint on to prevent any light leakage. That’s the key. One coat will definitely not be enough. Don’t be tempted to over-spray for thick coverage; it generally won’t dry evenly and you’ll get surface blemishes.
For Airbus Gray, BTW, the RAL code is 7016. You can order cans of this specific colour as a spray paint from specialist paint vendors online. That’ll get you an exact colour-match for the real aircraft.
