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Is there a way to polish LED after cutting/grinding it

Discussion in 'LEDs and Optoelectronics' started by LegendPanda, May 19, 2014.

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  1. LegendPanda

    LegendPanda

    2
    0
    May 14, 2014
    Hello, this probably sounds like a crazy idea, but I have to try :). I'm trying to turn a full-sized LED (10mm in height and 5mm in diameter) into a smaller LED. I've used a Dremel to cut and grind it to 5mm in width and height and it works fine. Is there a way to polish the LED semiconductor so it wouldn't absorb light as well as heat?

    I have no idea what semiconducting material it is :(. The light is blue and according to Wikipedia it can either be gallium nitride or indium gallium nitride.

    Any ideas would be appreciated.

    P.S. The obvious idea would be to buy smaller LEDs instead of cutting the large ones :D. I'm just curious.
     
    Last edited: May 19, 2014
  2. shrtrnd

    shrtrnd

    3,795
    503
    Jan 15, 2010
    I'm ASSUMING you're asking about buffing or 'polishing' the plastic lens material, not the emitter (the electrical part) itself?
    I do that a lot with plexiglas when doing woodworking. There are a lot of buffing compounds to use with a buffing pad on a Dremmel or other rotary buffer.
    The issue,is making a safe holder for your LED to hold it in place while buffing the plastic lens. You have to be sure it's well secured so the spinning wheel doesn't dislodge it from the holder while you're working on it.
    Google buffing or polishing plexiglas, and you should get some good ideas.
    (p.s. there are several types of buffing compunds available. It might take a few tries to get the one that works best on the material comprising the LED lens material)
    Good luck, and wear safety glasses.
     
  3. daddles

    daddles

    443
    3
    Jun 10, 2011
    I'll assume you're left with a flat surface and you want to make it optically transparent so that it doesn't scatter light. For a quickie one-off thing like this, I'd head to my shop and hand-polish the thing on finer and finer grades of sandpaper. You can go up to 600, 1200, and finer grits and get a pretty nice surface. To polish to transparency, one thing I used 50 years ago was Meguire's Mirror Glaze. It works on vinyl and acrylic (at least it did then). You had to rub a lot, but it would eventually get the job done.

    Another thing to try is fire-polishing. This is where hot air is used to melt the surface of the plastic and get a transparent finish. But you'd better practice on some scrap first, as it's not trivial. It's similar to fire polishing cut glass tubing like we used to do in elementary chemistry classes (they probably do that today with a computer simulation :)).
     
  4. KJ6EAD

    KJ6EAD

    1,114
    159
    Aug 13, 2011
    I don't think fire polishing will work in this case; LEDs are mostly potted in epoxy which will tend to discolor, char, or ablate before the surface liquifies.

    After wet sanding in stages to 1200 grit, the 3-stage Novus plastic polish system will work similarly to Meguiar's.

    http://www.novuspolish.com/
     
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