Cutting LCD lenses?

Discussion in 'General Electronics Chat' started by spinnaker, Dec 23, 2010.

  1. spinnaker

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    I am looking at making a lens / cover for LCDs for a couple of projects. I was thinking of using the same material for a cover / front panel for a few other projects.

    The Home Depot has several types of plastic sheeting, Acrylic, poly carbonate etc.


    What is the best material to work with cutting wise?

    I have one of these. It takes pretty much any kind of blade. Is there a special blade for cutting this material?


    I tried cutting a CD cover with a fine tooth metal blade but it just melted the edge. I think I might try a slower speed.
     
  2. retched

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    Wow. I really like that blade runner.

    I made my own by mounting a jigsaw under a tabletop, but It was a PAIN to switch blades.

    I really like that vacuum attachment too.

    As for your lens, get window or optical grade 1/8 or 1/4 inch lexan.
     
  3. Kermit2

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    Wax. Plain old candle wax. will help you cut the plastic smoothly.

    And before you come back tomorrow and ask. Turpentine will dissolve/remove wax from plastic. And alcohol will remove the turpentine oils if it leaves any. :)
     
  4. spinnaker

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    The only thing I do not like about it is the table does not tilt. So I cannot rip mitered cuts. Of course I know little about woodworking so maybe there is a way to do it.

    It is easy to switch blades. I bought the circle cutter attachment which seems pretty cool but not sure where I will use it as it is for bigger circles.

    It comes with a free wall mount attachment that I still need to mount. Instead of the wall, I think I might try to mount it on the end of my workbench.



    As far as the lenses. I do not need anything fancy. Would a more readily available material do?

    BTW if a mod wants to move this to another forum that is fine with me. Just was not sure where it belonged.
     
  5. jpanhalt

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    1/4 inch Lexan? What are you packin'?

    Acrylic may be slightly easier to work with. Either will work and all you need is 25 mills, unless you are planning target practice.

    John
     
  6. spinnaker

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    Thanks for the tip. I will give that a try. Fast or slow cut? Should the blade I am using work?
     
  7. jpanhalt

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    Whatever blade you use will leave melted plastic. Drilling is another matter. Dub off the lips on the drill or it will hog in. If you are drilling and don't know what that means, post back.

    John
     
  8. spinnaker

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    I don't know what that means. :)



    So how do I cut the stuff other than scoring and snapping?
     
  9. spinnaker

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    Actually the wax idea worked pretty well. Just a bit of melting.

    But I have another issue, the material is cracking a bit. My guess a CD cover is far too thin and brittle but it is pretty much all I have on had right now.

    And I am steering clear of the shopping centers until at least Monday! :)
     
  10. jpanhalt

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    Basically, you run the sharp lip of the drill at the tip against the side of a grinding wheel to remove the acute-angle of the cutting edge. Now, instead of cutting into the plastic, it scrapes the surface. The chip will be like a snake skin. This is useful for hard plastics and brass that tend to pull the drill into the material (i.e., hog in). You don't have to remove much to be effective -- just so you can see a flat face. Obviously, drills modified in that manner are not good for steel or aluminum afterward.

    [​IMG]

    My drawing sucks. If it is not clear, say so and I will try a real photograph.

    John
     
  11. spinnaker

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    I think I understand OK. I will need to take a close look at a bit to be sure.

    I suppose I should use an extra bit as this is probably not the best thing to do to a bit if drilling metals?
     
  12. Kermit2

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    The best method to drill through plastic without destroying your drill bits is to sandwich it between two pieces of wood. Clamp them tight.

    A bit of acetone will smooth out the cut edges of the CD cover plastic and leave them shiny, smooth and slightly rounded. Don't get any on the flat surfaces though, it dissolves the plastic very fast.
     
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  13. jpanhalt

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    It is one of the best uses for cheap drills from Harbor Freight. Just keep in your mind's eye that you want to scrape the plastic, not cut into it. With a small drill , say 1/8" or less, you can get away without the modification. But on 1/4" and larger, I would always do the modification. There is nothing worse than getting a crack on that last hole.

    Remember, it is just the tip flute. And, if you want, you can always resharpen the drill to a normal cutting edge, but it is generally not worth the effort to do that for the smaller drills or cheap drills.

    John
     
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  14. jpanhalt

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    I just noticed the comment about using CD cases. They are not acrylic or polycarbonate, but rather a very cheap styrene (I think). Styrene is quite prone to cracking (thus the need for dubbing) and it crazes when exposed to various organic solvents. The crazing may not occur until quite awhile later.

    John
     
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  15. Markd77

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    Even water is an improvement on just drilling dry if you are worried about the lubricant effecting the plastic. It provides a small amout of lubrication and helps lower the temperature.
     
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  16. jpanhalt

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    I generally use water too with a drop of dish washing detergent. The main purpose is cooling, and the surfactant helps with the hydrophobic plastic. I avoid organics, including wax, as their long-term effects are hard to predict.

    John
     
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  17. marshallf3

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    It's so simple to pick up scraps of true lexan from any wholesale plastics dealer, mine charges 50 cents a lb. Grab a bunch and you've got a ton to play with for now and the future.

    Sometimes cutting a very small lens requires a hot knife followed by a file &/or sandpaper.

    Normally I just but the 10 cent lenses from Mouser, they not only have a built in Fresnel lens but also hold the LED. A $2.99 hot melt glue gun from Hobby Lobby or any other cheap tool place is handy to have as well.
     
  18. spinnaker

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    How do you find such a place?
     
  19. Kermit2

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  20. marshallf3

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    Yellow pages. plastics supplier, wholesale.

    They'll all have a scrap bin if you ask and if you find one that's willing to cater to you you can get the stuff for next to nothing. Just be sure that you pick out a lot of choice pieces and put them in stock, they don't take up any space to speak of and you will find a multitude of uses for the good plastic over time.

    Hint: If they sell the Weld-On #4 adhesive pick up a bottle of that too, it welds Lexan or Plexiglas like magic but you will need a ventilated room to use it in.
     
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