Laser Engraving and material selection

[Tomlin]

Hi guys

I may have to find a way to have some panels made if I cant find another source in time for a flight event that is coming up that Im hosting, so Im looking into have a local engraver make some simple panels for me.

Some questions on lettering:

It appears that the white lettering on commercial panels is very, very close to the top of the panel surface, and Im guess that when those are lasered on, that the laser is just removing the gray paint from the acrylic, correct? If this is true, then Im also guess that it is neccesary to have an opaque material vs. a clear acrylic, right?

So, what if milky/opaque material is not available, what would be the procedure? Is it possible to paint the material with several layers of white and then paint it gray and have the laser take of just the gray?

Thanks for those in the know. I have a friend who works at the place with the laser engraver, but he's never used it and is going to try different things to see what happens.

Appreciate your ideas and thoughts,

[AndyT]

I would use clear plastic behind the grey paint. That way when you get the engraving done, leave the inside of the lessters a bit rough so that a light behind the panel will light them up at night. A poor mans EL system.

[phil744]

In my prototyping shop at work we have a 1 year old laser scriber and I’m the only person who can use it and I have the keys to the unit, thus why I am making my own panels usually in the middle of the night. ( Shh!!!, dont tell the boss )

I have spent a long time trying to find the best combination that works, and what I do is simple.

Piece of 6mm clear acrylic, then give 1 precise coat of white, no more than 1 or you will screw up the back lighting, then a couple of coat's of satin black, this adds a barrier to stop light bleeding through, then a couple of coat's of brown or grey (AC depending) then let the whole lot cure.

The paint I use is the stuff you get from any automotive shop, here in the UK I use Halfords (but a special color mix for the top coat, but same paint type)

Once on the Laser you will need to find the best settings depending on your machine, on my machine I use a travel speed of 280mm/s laser power to 61%, laser frequency@ 4Khz, wobble 2 and when you create the "fill" on your artwork always spiral the design to center of the of each individual font, letter or image's ( Basically meaning it will draw one letter at a time then the laser will work on an inwards spiral direction to the centre of the letter before moving to the next), Never cut the artwork in a left to right motion, you will lose a lot of the clarity.

When complete give it a coat of "Plasti-Kote" clear satin acrylic for a nice matte satin finish and protects your artwork and makes it indestructible!!

If that don’t work take the clear Perspex and cover it with a piece of white vinyl type film, or the type u need to heat shrink (stuff used for model aircraft type, but I can’t remember the name). give it a quick wet and dry paper, no grade lower than P800 then paint your topcoat, I believe that can work as well but I have never tried it.

Below is one 747 rejected EFIS panel I knocked up a while ago to trial the machine and artwork befor i threw it in the bin, spot the fault with the artwork





and my machine making display PCB's for me,
http://s17.photobucket.com/albums/b5...rent=Movie.flv

[brianwilliamson]

I basically use 3 or 6 mm. acrylic which is white, and spray paint it with the desired colour in automotive laquer, and then engrave. The white gives a good readout without the backlighting, and is very good at night with the backlighting ,as well. I use a mechanical engraver, not laser, but the results will be similar.
Cheers.............Brian W.

[brianwilliamson]

Here it is with the backlighting...........
Brian W.

[Matt Olieman]

Looks fantastic Brian of course I already knew that

[brianwilliamson]

Thanks Matt. Hey, when are you coming over here to teach me how to fly my 'Bus ??
Cheers.................Brian W.

[Matt Olieman]

LOL, I thought you would be expert by now Brian

[Tomlin]

Boy, oh boy- This is excellent information, and well recieved. I will use this to the fullest extent possible. Thank you all for the info!

[DAL900]

If I may suggest, having made some panels the “Boeing” way. Depending on the material you decide to use lexan or whatever, if it is clear do the following:

- prep it by giving the engraving side a light wet sanding using 800-1000 grit
- paint it white evenly, several coats. Check evenness with a light from behind
- paint the second layer clear
- paint the third layer black
- final layer your choice of color for the panel

*** Important ***

Paint a scrap piece at the same time the same way at the same time. This piece will give the laser engraver a sample to work with to set the depth of the laser. It’s better to lay the white on thick then try and come back and fill it later if the laser goes thru the white