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Thread: Engraving Acrylic

  1. #1
    Join Date
    Nov 2011
    Location
    St. Joseph Mi. 49022
    Posts
    8

    Unhappy Engraving Acrylic

    I do a lot of lighted acrylic signs. I'm using a carbide 45 or 60 degree cutters. I cut between .o15 to .o35 deep. I have tried spindle speeds of 10,000 to 14,000 RPM, and feed rate of .3 per second. I installed a mister on the shopbot and run water and a little bit of Johnson baby oil in it. This has helped 90 percent to stop the chips from sticking in the groves. But still not 100 percent. I then have to try and scrape the rest out by hand or with air hose. If I'm not careful I will scratch the acrylic. Not good. Any ideas? thanks

  2. #2
    Join Date
    Mar 2013
    Location
    Memphis TN
    Posts
    691

    Default

    I'm guessing the basic issue here is insufficient heat removal. Either increase the feed rates or decrease the RPM's to increase the heat rejection. The chips are sticking because they are partially melted.
    ShopBot Details:
    PRS Alpha 96x60x12
    4hp Spindle
    12" indexer
    Aspire
    Rhino

  3. #3
    Join Date
    Mar 2005
    Location
    Beckwith Decor Products, Derby/Wichita KS
    Posts
    604

    Default

    As coryatjohn noted above your not hitting the chipload with your feed and speed.
    for acrylic, 48ipm 8000rpm for small letters (.5), 60ipm 10000 for larger
    then you don't say what tooling your using, not all v-bits are suited to cut plastics so your tool selection maybe a hindrance to your cut as well.
    Gary
    Beckwith Decor Products
    Custom CNC Tooling/Onsrud Distributor


  4. #4
    Join Date
    Dec 2007
    Posts
    2,292

    Default

    Are you using cast or extruded acrylic that make a big difference

  5. #5
    Join Date
    Nov 2011
    Location
    St. Joseph Mi. 49022
    Posts
    8

    Default

    Which is better. I can get both. Thanks

  6. #6
    Join Date
    Nov 2011
    Location
    Mission B.C.
    Posts
    122

    Default

    Quote Originally Posted by badboys cnc View Post
    Which is better. I can get both. Thanks
    Cast acrylic is best.

    Rik

  7. #7
    Join Date
    Mar 2013
    Location
    Memphis TN
    Posts
    691

    Default

    Cast is also usually more expensive... I don't think there's much 1/4" cast acrylic around.
    ShopBot Details:
    PRS Alpha 96x60x12
    4hp Spindle
    12" indexer
    Aspire
    Rhino

  8. #8
    Join Date
    Dec 2007
    Posts
    2,292

    Default

    Quote Originally Posted by coryatjohn View Post
    Cast is also usually more expensive... I don't think there's much 1/4" cast acrylic around.
    I use a lot of 1/4 cast acrylic many different colors Most I cut on my laser but I do some on the bot. Easy to get cast if you order from a supplier

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