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Modding I've got the "working with acrylic blues!"

Discussion in 'Modding' started by hagatha, 27 Aug 2007.

  1. hagatha

    hagatha No Guts? No Glory!

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    I'm looking for some advice, hints, how to's, or just plain help! I've read a lot of post on "how to" but they seem to be lacking the exact particulars I'm needing.

    Here's the problem... I'm getting small bubbles in the glue joint as it drys. When I sand the joint and buff it out, the bubbles become small pock marks and fill with the buffing compound and it is near impossible to get it clean again.

    Materials: 3" clear acrylic tubing, 1/2" Lexan (caps) and #16 weld-on glue with needle applicator and lots of sandpaper.

    Procedure: sand end on tube flat starting with 220 dry and working up to 1000 wet. Clean and dry both surfaces, test fit... (perfect). Apply a thin bead of glue to the edge of the tubing... clamp pieces together and leave clamped for a couple hours... remove clamp let sit over night before sanding. Sand joint and surrounding area smooth, starting with 400 wet and working up through 600 and 1000 wet. Buff joint with buffing wheel and #6 (fine) buffing compound.

    Is it the wrong glue? problems with joining acrylic and Lexan? what am I doing wrong... (I have access to lots of "usable" scraps of thick Lexan"

    The joints don't leak and are strong... but they are not the crystal clear joints like I see Tribaloverkill doing, along with some other examples I've seen on line?

    Come on guys... whats the secret??

    Lee
     
  2. CollinstheClown

    CollinstheClown Hi

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    I think your supposed to use Weld-On #4. I have it and didn't have bubbles or anything of that sort. Not sure if it will work with lexan or not, havn't had the chance to try it yet.

    http://www.ridoutplastics.com/ips4.html




    -CollinstheClown
     
  3. radodrill

    radodrill Resident EI

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    Yep; wrong glue, the #16 is way too thick. You should be using something like the #3 Weld-on or Polycarbonate Cement SC-325; they are water thin and don't make any bubbles. You simply clamp the parts together, then (using a fine needle on a bottle, ~25Ga) apply the glue at the joint and it'll seep in between the pieces to glue them together.
     
  4. Teyber

    Teyber ******

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    no, don't clamp the parts together. This will cause crazing, just put it on and just let it rest, or so says tribaloverkill. Sanding with high friction sanders can do this, like a belt sander. Try avoiding powersanding, and perhaps clean the material first?
     
  5. Cheapskate

    Cheapskate Insane? or just stupid?

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    Yup- The gel weld on glue is for filling in really bad fits only. The more you add -the more bubbles. If it's Just in a seam it tends to be crystal clear. Are you having any problem with the lexan clouding?
    You could experiment with a thinner glue or acetone to remove the sanding debris in the bubbles. -Note that I said experiment here.
     
  6. hagatha

    hagatha No Guts? No Glory!

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    The Lexan and the acrylic bonded nicely. There was no crazing or clouding of either material... only the bubbles in the glue. I've ordered some #3... we'll see how that works. I really like working with the Lexan... it machines so much cleaner than acrylic... and I get lots of usable scraps too, from .25 - 1.375".

    Lee
     
  7. Cheapskate

    Cheapskate Insane? or just stupid?

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    It machines nice, but you have to file it down, rather than sand it. anything more than 150 grit sandpaper just gouges it.

    I asked about clouding because I had problems with prophylene and acetone clouding.
     
  8. Cheapskate

    Cheapskate Insane? or just stupid?

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    OK, It's a little late, but it seems it's the lexan itself that forms the bubbles. I just useed my tap acrylic solvent to glue some polycarbonate and it REALLY softens up when the glue hits it. When I applied pressure I got more bubbles.
     

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