Page 1 of 2 12 LastLast
Results 1 to 10 of 13
  1. #1
    150+ Forum Groupie
    Join Date
    Sep 2006
    Location
    Netherlands
    Posts
    165
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Extruded Acrylic/Plexi : BEWARE

    Extruded Acrylic/Plexi : BEWARE

    Hi guys,

    See pictures.

    NO, this is not a story about my wife's sewing-work-table......

    BUT, have look to the ***clear acrylic plate*** on it.

    After a few years the (previous perfect) edge got a few thousand crackles.

    I presume this is/was ***extruded acryl*** (i.c.t. casted acryl).

    The heat of the cutting gives (even after years) exagerating tension (this was already intrinsic in the material) and causes this kind of "problems".

    I'm not really sure if this an important issue for our panels, but think about it !

    Hessel
    Attached Images Attached Images
    767 Level-D

  2. #2
    Super Moderator
    Join Date
    May 2006
    Location
    Texas
    Posts
    616
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Extruded Acrylic/Plexi : BEWARE

    My guess would be the method used to radius the corners gave the plastic brittle characteristics. I have seen some companies use plastic router methods to shape edges before instead of a laser, perhaps this is the result.

    Hessel did you make or cut the plastic?

  3. #3
    150+ Forum Groupie
    Join Date
    Sep 2006
    Location
    Netherlands
    Posts
    165
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Extruded Acrylic/Plexi : BEWARE

    Hi Joe,

    Spoke you shortly before isn't it ? ...

    I use a small cnc router and file the radius by hand.
    Don't know how it is done in the plxi I showed in the pictures.

    Hessel
    767 Level-D

  4. #4
    300+ Forum Addict phil744's Avatar
    Join Date
    Aug 2007
    Location
    Lancashire, england
    Posts
    336
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Extruded Acrylic/Plexi : BEWARE

    Hey Chaps, thats nothing to do with the plastic being cast or extruded, whats happened there is after the plastic has been cut and the radiused edges applied that piece has been flame polished without annealing afterwards.

    Hessel, if you have some thinners, or borrow the wifes nail varnsh removed put a smal ammount on a cloth and dab the edges of the acrylic, and watch the cracks grow, normally flame polished acrylic is okay but the edges are hard in comparison with the rest of the acrylic being soft, when chemicals are applied it softens the hard edges of the acrylic and the stress within causes it to crack, the problem is less obvious with casted acrylic but it will still happen, the problem is even less with white and solid coloured acrylic
    - - - - - - - - - - - -
    Philip Lambert

    747-400? nah probably 767 now, FS9, FDT simboards , dunnow about software yet

    www.simvionics.co.uk

  5. #5
    150+ Forum Groupie
    Join Date
    Sep 2006
    Location
    Netherlands
    Posts
    165
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Extruded Acrylic/Plexi : BEWARE

    VERY usefull Phil !
    Thanks.

    Hessel
    767 Level-D

  6. #6
    10+ Posting Member
    Join Date
    Oct 2009
    Location
    Netherlands
    Posts
    10
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Extruded Acrylic/Plexi : BEWARE

    Quote Originally Posted by phil744 View Post
    Hey Chaps, thats nothing to do with the plastic being cast or extruded, whats happened there is after the plastic has been cut and the radiused edges applied that piece has been flame polished without annealing afterwards.

    Hessel, if you have some thinners, or borrow the wifes nail varnsh removed put a smal ammount on a cloth and dab the edges of the acrylic, and watch the cracks grow,
    Phil, I was told (by a local company selling plexi stuff) that this appears more/sooner on extruded acrylic than with the cast version.
    In extruded acrylic, due to the continuous extrusion and cooling down of the extruded plastic, there are uneven tensions in the material. This can result in cracks in the material - specially when it is being glued (your thinner).

    I guess you mean that one should not use thinner/solvents on flame polished acrylic to prevent cracks ? Maybe even not flame polishing at all ?

    I have been told never to use extruded acrylic for (laser)cutting but I am no expert. I guess I'll find out; I've still got some extruded white material and within a few weeks the laser will arrive

    Regards,

    Rob

  7. #7
    150+ Forum Groupie
    Join Date
    Sep 2006
    Location
    Netherlands
    Posts
    165
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Extruded Acrylic/Plexi : BEWARE

    Good day Phil, Goedendag Rob (new to simming .... ?,

    Here the effect Phil described.

    http://www.youtube.com/watch?v=w8MEh...eature=related

    Hessel
    767 Level-D

  8. Thanks autocadplease, Joe Cygan thanked for this post
  9. #8
    Super Moderator
    Join Date
    May 2006
    Location
    Texas
    Posts
    616
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Extruded Acrylic/Plexi : BEWARE

    I Just poured alcohol on some laser engraved panels (clear & colored) and nothing happened to it. Must be what Phil is talking about with flame polishing edges.

    Joe

  10. #9
    10+ Posting Member
    Join Date
    Oct 2009
    Location
    Netherlands
    Posts
    10
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Extruded Acrylic/Plexi : BEWARE

    Quote Originally Posted by Joe Cygan View Post
    I Just poured alcohol on some laser engraved panels (clear & colored) and nothing happened to it. Must be what Phil is talking about with flame polishing edges.

    Joe
    After unpacking, cleaning, mounting and aligning of the laser equipment and installing of the software we got our laser working and I could not resist ...
    Attached is an image of a test on some plexiglass from unknown origin but most likely this is XT (extruded) matte white plexi.
    The result looked great but after pouring some alcohol (isopropanol) on it it did not take long to develop cracks in both the cut and the engravings.
    The number 2 on the image has a height of about 9 mm.

    Regards,

    Rob
    Attached Images Attached Images

  11. #10
    Super Moderator
    Join Date
    May 2006
    Location
    Texas
    Posts
    616
    Contribute If you enjoy reading the
    content here, click the below
    image to support MyCockpit site.
    Click Here To Contribute To Our Site

    Re: Extruded Acrylic/Plexi : BEWARE

    Quote Originally Posted by Rob65 View Post
    After unpacking, cleaning, mounting and aligning of the laser equipment and installing of the software we got our laser working and I could not resist ...
    Attached is an image of a test on some plexiglass from unknown origin but most likely this is XT (extruded) matte white plexi.
    The result looked great but after pouring some alcohol (isopropanol) on it it did not take long to develop cracks in both the cut and the engravings.
    The number 2 on the image has a height of about 9 mm.

    Regards,

    Rob
    This is certainly interesting. Wondering why yours cracked and my does not. What type of laser are you using? What type of plastic did you use?

    Joe

Page 1 of 2 12 LastLast

Similar Threads

  1. Drilling Through Acrylic!
    By CessnaGuy in forum General Builder Questions All Aircraft Types
    Replies: 13
    Last Post: 10-06-2009, 11:28 PM
  2. Beware of 737ng
    By capttlm in forum Welcome to MyCockpit New here? Introduce Yourself!
    Replies: 0
    Last Post: 09-25-2009, 04:46 PM
  3. acrylic mirror size?
    By steve diamond in forum General Builder Questions All Aircraft Types
    Replies: 1
    Last Post: 09-19-2006, 03:01 PM
  4. Beware of memory bank height when using big coolers
    By ekezz in forum I/O Interfacing Hardware and Software
    Replies: 0
    Last Post: 12-18-2005, 10:24 AM

Tags for this Thread