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Engraving transparent stuff, making shiny things

2016
24
June

When I received this laser engraver, I read warnings against attempting to engrave transparent or metallic materials. Good thing I'm not a smart guy, so I decided to try it anyway. It had to work. Guess what? Turns out it works a treat!

I decided to try and make LED illuminated signs, kind of like those "exit" signs you see places. The principle is simple: light passes through the sheet, and wherever there are bumps, engravings or scars, light will exit.

I bought two sheets of 300x300x2mm styrene acrylonitrile. They are easy to cut and come with a protective film on each side. This is a good thing, because these guys scratch easily. The sheets were cut by tracing the desired route with an utility knife, and then giving it a friendly whack to split the board.

Here's the sheet with the protective film on each side intact.


Here you can see the transparent sheet (without the protective film) being engraved. It's from another project, but shows the job being done. It had to run at a low speed in order to have an impact on this particular material.


Dickbutts aside, here's the first successful project I made. A square blue LED is superglued in an bottom insert, flush with the rest of the board. The edges are quite illuminated, this can be prevented either with electrical tape, or painting the edges with a solid colour. I think it looks cool the way it is.


Here's the CR2025 battery wedged between the LED's cathode and anode pins, which conveniently serves as a rest. The internal resistance of this battery is so high that a current limiting resistor is not required.


By adjusting the focus and the burn time, I was actually able to cut through the 2mm styrene acrylonitrile completely. However, while experimenting with this I stumbled across something unexpected - but I'll save that for a later post. (How's that for a cliffhanger ending?)


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4 Comments

  • Dear,

    I have the same NEJE engraver as yours but I can't engrave plexiglass.
    On your video, what are you placing below the plexi sheet please?
    What is the your engraving speed? I mean burning time? (from 0 to 240)
    Thank you for your help and kind regards from Belgium

    Bertrand

    #1046 | Comment by Bertrand on Dec 8, 2016 08:31am
  • Bertrand: I don't remember the settings, but IIRC the burning time was pretty long. Like, 150-ish or so.

    The plexi glass is actually styrene acrylonitrile, bought at a local hardware shop. It's fully transparent. I did fiddle a little with the focus to adjust the burn point, but this was done by guessing.

    I can repeat the burn when I get time, but I'll have to start from scratch again. If you want to try it yourself, just set the long burn time, and adjust the focus until it burns just right.

    #1047 | Comment by admin on Dec 8, 2016 11:17am
  • Hello! I have a question about this process. What is the black material placed behind the plastic? also I see you used washers as sort of stand offs, is this necessary? so that the plastic does not melt to the backing material?

    #1082 | Comment by David on Sep 19, 2017 05:36pm
  • David: The black cardboard in the background was just for protection so I wouldn't burn the base plate any more than I already have :-)

    The standoffs are not required either. I honestly don't recally why I placed them there.

    Just focus the beam on the top surface and start burning.


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