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clear acrylic etching

Hi guys, I'm looking for insights other experimenters might have. I started with a clear acrylic sheet and had no luck etching it. So I painted one side with 'chalkboard black' and then tried again. It worked...sort of.
1) I dithered my image
2) set the speed down to 500 mm/minute
3) otherwise left the system in the analog mode that I used to etch plywood

Looking at the result, I need to generate a negative of my photo first. I see where plastic has been etched away which is good. I probably needed to increase the speed to 750-1000 for acrylic.

Here's my question. I'm ultimately looking to use this same process on the backside of a mirror tile that I picked up at home depot. Would I be better off not dithering? Has anyone tried a variation of this themselves?

Comments

  • Hey Peter, are you using casted or extruded acrylic? Casted will yield the frost effect, extruded will not. I haven't tried it myself yet but i will so(maybe next week). If you're in the states, I bought a bunch months ago from these guys. They have $2 samples you can add for testing purposes and it doesn't really increase the shipping price.

    http://www.tapplastics.com/product/plastics/cut_to_size_plastic/acrylic_sheets_super_thick_clear/510 well priced and knowledgable tech support.
  • Hi Peter,

    In PEP5 use flip image then Negative Colors selection for back of mirrors. More power will burn more and looks white in the front and less power will be the reflective silver and appear like black. Try to find mirrors with the white, evenly coated backing. The gray backed ones do not burn very good with a LD.

    If you look in our gallery page, there are examples of mirrors we have done using varied intensity instead of pulsing with a dithered image. Make sure you have good ventilation when you try mirrors.
  • By mistake I learned, that if you give in Piclaser lite maxlaser value 10 and minlaser value 100 you end up with negative image! Took a while to figure out what's wrong.
  • edited January 2015
    For PicLaser Lite users, mirror image in an editor first, then do like Jyri did.
    :-)
  • Thanks guys. I'll reach out to the folks for the cast acrylic that sounds promising. on the mirror side, I bought the gray backed ones. I'll let you know if I find a way to get them to work. I may just cheat and paint the front side with white paint and then etch it off. so many things to try and so little time! I should have bought two of these machines :-/
  • edited January 2015
    Hi Peter,

    We have had good success etching text onto acrylic and then edge lighting it. It looks fantastic at night, as the light only picks up the engraved parts in the acrylic. We have not tried shaded images from PLL.

    Our process was to give it a very thin and even coat of black paint. The evenness is important to ensure your engraving depth is consistent. Think of the paint layer as concentrating the lasers power and initiating the melting process, rather than just passing straight through the clear material.

    We used CutLaser-2D to create the engraving files and found we could get good results by experimenting with the spacing between the engraving lines. Too close and the result was blurry. Too far apart and you don't achieve a coherent look.

    Please ensure you have good ventilation when working with acrylics and other plastics. The fumes could be harmful or an irritant.

    You can just see the engraving lines in the image below:

    Award Pic Light+Dark_small
  • Did you laser cut the plaque? Or CNC it? by any chance do you recall what settings were used? The plaque came out fantastic.

    I just realized, were we supposed to get one of these with our machines? Mine is mia if we were haha. Maybe you could upload the files? I'll try replicating it.
  • My wife came up with a suggestion on this; use some dark colored Contact Film (the stuff you cover kids books for school so they last longer)
    http://www.officeworks.com.au/shop/officeworks/contact-adhesive-book-covering-1-metre-ja0359170

    I'll give it a try soon and report back
  • Hey David,
    There is a good chance that the contact paper is PVC, be sure your ventilation is adequate. good luck!
  • Hi Joseph,
    The plaque was routed. Laser cutting would be a better option because it would leave the edge clear and allow more light to enter.

    We did some tests at running a flame over the edge, which did remove the frosted look but was very difficult to get a nice consistent result.

    The backer awards were a specific pledge level. They do not come with every kit.
  • David,
    As Chris mentions, be very careful with any material that may contain chlorine. Apart from it being harmful to you it will also cause all the metal parts on your machine to corrode. We know this from a first hand experience.
  • So I tried doing the cast acrylic today. no dice. The laser light just defuses.

    I did a test on a piece of smoked acrylic but the frost wasn't very strong. Seen in the first picture.

    After that I experimented a bit more and tried something before calling it quits for the night. I put a piece of paper between the clear acrylic and it cut through the paper which then fused to the acrylic which then melted it. After slowing the speed to 30 inches/min and 255 power it seemed to etch really nice as you can see in the picture. I did notice if you don't have the paper on flat on the acrylic it will fog and smoke it as if it's stained. This happened when I did a test on a small piece of smoked acrylic. I'll have to try this again with a perfectly cut piece of paper.

    I'm going to do some more testing tomorrow after I fabricate a proper ventilation system here. It didn't create any smoke or harsh smell beside paper burning. I obviously stayed in the other room and ran a fan for health reasons but man it's freezing outside with the window open. haha, And I don't particularly feel comfortable burning paper while not observing the process the whole time. I popped in every few minutes.
    2015-01-30

    2015-01-30 (1)

    this is the clear side up and the etch on the opposite side facing the table. Just a quick test. I have the resolution set to .006 inch. If i set it to .003 would it make the lines closer?

    What i did was place regular printer paper on the acrylic then had picengraver do a laser edge set to 2 so it would cleanly cut the paper so it would sit perfectly on top and not curve. It was really easy to replicate. I am curious if a faster feed rate is possible at a finer pass.
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