Gents / ladies, I would like to use my CNC engraver to make some illuminated fascias for my DIY flight sim 'cockpit'. I've been able to make some really nice fascias that are essentially black painted engraved MDF, with the lettering filled with suitably coloured paint, and have CNC engraved circuit boards that mount to the back of the fascia that the switches, potentiometers and encoders all mount onto really neatly. So I am most of the way to where I want to get to, but what I really want is to be able to mount some surface mount LED's onto the circuit board, and have the front of the fascia made from a material that lets the light show through the lettering.
To that end, I have tried coating some clear acrylic sheet with black paint (tip - you really need to sand the surface of the acrylic to get the paint to stick firmly, more later) and then engraved the lettering plus cut out the holes and external profile with the CNC router / engraver, using multiple steps to 'build up' the details. Unfortunately this is not going well. The letter engraving is not bad, although it could be better. As you can imagine, by engraving through the black layer of paint, any light behind will shine through what has been engraved. For some reason it is not a good finish, and initial attamts showed that the paint would be chipped off from around the engraved areas, hence the need to really give the paint a good key - using a laser for the lettering doesn't give much advantage as it ends up with raised edges, making it impossible to finish smoothly without eradicating some of what you try to achieve.
When it can to cutting out the component holes and the outline, things got worse. The component holes I could live with as essentially I can drill though from a pilot hole smaller than the final hole, but the outline? Oh dear, no - rather than just cutting, the milling cutter ends up melting the acrylic into blobs that clog up the cutter and also spin round on the surface screwing up the area around the cut. Additionally, some of it blobs of and welds itself to the rest of the workpiece so that when the next pass comes it pushes the cutter out of line.
So really I would like some advice on what materials would be better suited to this. I accept that I am probably going to have to find another way to cut out the outline of the panel as I can't see any way round the melting issue. However it did occur to me that I have seen some plastic sheeting used for signs that comprises two layers, a white substrate with a black layer overlaid. When engraved, the white layer is exposed and that would work for me, I think. However I can't find anything on fleabay or amazon, and locally here in Hungary I would not even be able to know where to begin.
Also, while I assume that those plastics are more suitable, I think I would like to know a bit more before committing. I also would welcome any alternatives to my ideas, as it may be that I am overlooking a simple solution.
As ever, any help or suggestions gratefully received!
Cheers
Les