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Thread: Shaping Plastic

  1. #1
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    Shaping Plastic

    I am trying to make the front window for my mech, in order to shield the camera from BB's. It is going to be an oval shape that will be pushed out about 1/2 cm to 1 cm. I am using Lexan as it is very durable against the BB's.

    So I tried it a few times with making the shape in a piece of wood, clamping down the plastic all around, heating it up with a heat gun, and pushing it through the cut out with different rounded objects (tools, spoons, etc.). The final product comes out to the plastic being pushed about to 1/2 cm, but have a lot of scuff marks and strange patterns when you look through the plastic (which would all show up and distort the image from the camera). Those are the good outcomes, the bads ones consist of melted plastic, small bubbles.

    ~ So I wanted to know if anyone has any experience with trying to shape the plastic?

    ~ If this idea to make it that far out and smooth if possible?

    ~ And, would the use of a vacuum former be the better route? (I've been thinking about this since my attempts didn't turn out that great)

    Thanks for any help people can give me on this type of project.

  2. #2
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    Re: Shaping Plastic

    How thick is it? I've seen good vacuum forming results with PC, PET, and PETG. But thick plastic is always harder to work with. Bubbles are caused by overheating. Heat guns are going to be hard to control. A radiant heat source is going to be better. Can you clamp some in a frame and put it under the broiler for a while?

  3. #3

    Re: Shaping Plastic

    Hi
    I seen a clip on youtube using a pyrex lid that has the right curve then put it in the oven on the lid until its soft
    if it dos't pull down enough apply a vacuum to the hole in the lid



    peter

  4. Re: Shaping Plastic

    i know you probably don't want to make a vacuum former, but the rc people have very good results with this method.

    [ame="http://www.youtube.com/watch?v=BVVE5EHzRnk"]YouTube - Vacuum Forming Home Style[/ame]

  5. #5
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    Re: Shaping Plastic

    Lexan has a quite high water content. Which makes it very prone to bubbles. I've bent it using heat, but always had a problem with bubbles. I would second the suggestion for PETG. Or try to avoid the dome type of shape.

    Gary
    Team Maggot---Mechs. "Bheka" (retired), "Maggot Mk.3(A)"
    " Keep your stick on the ice ".... Red Green

  6. #6
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    Re: Shaping Plastic

    So, I got it done today. I didn't have a vacuum former, but I tried to use the same idea of it. I made two molds. One with the same cut out as the window. And also one of the shape that would push the plastic. So then I attached the plastic to the one of the cut out, heated it up in the stove (so not as hot as a heat gun, and more of the same heat all over). Then I pushed the plastic and cut out down over the mold using some guides to make sure it went on straight.

    And the final result ended up with a nice clean plastic bubble, that sits perfectly in the window of the mech to protect the camera. So I am really happy with it.

    GDUBB - I forgot I was using PETG as well. I had ordered it when you mentioned it last time I had a question about this. And just forgot that it was PETG that I had in my possession. So thanks for the help.

    Thanks to everyone also that helped out on it and gave me advice and ideas, that helped me make this work.

    I will post the pictures if I get to it tonight, if not tonight then definitely tomorrow after work.

    Attachment 2343 Attachment 2344

    Attachment 2345 Attachment 2346 Attachment 2347
    Last edited by elaughlin; 01-17-2011 at 10:45 PM. Reason: Adding pictures.

  7. #7
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    Re: Shaping Plastic

    Very nicely done.. looks great.

    Gary
    Team Maggot---Mechs. "Bheka" (retired), "Maggot Mk.3(A)"
    " Keep your stick on the ice ".... Red Green

  8. #8

    Re: Shaping Plastic

    A while ago I was looking for clear domes for a project.

    That night I was watching "How its made" on the discovery channel and they did a piece on

    Marine Compasses. They are covered by a clear dome. ( Lightbulb flashing)

    They are a little expensive but they look really nice.

    http://www.ritchienavigation.com/

    Here is some sizes and pricing.

    Hello John,

    Below are our dome sizes. Attached are drawings. Pricing is dependent on quantity ordered


    Part #

    Diameter*

    Thickness*
    List price per Dome**
    Order Quantity/
    Discount**
    EX-0011
    2.907
    0.094
    $7.78
    20pcs. -- $5.83 per
    TR-0001
    2.5
    0.1
    $6.25
    20pcs.– $4.68 per
    VY-0017
    3.56
    0.128
    $12.50
    20pcs. -- $9.38 per
    HL-0020
    4.054
    0.127
    $15.00
    15pcs. -- $11.25 per
    NV-0022
    4.68
    0.141
    $23.44
    15pcs. -- $17.58 per
    5G-0131
    5.58
    0.209
    $37.00
    10pcs. -- $27.75 per
    5G-0040
    5.8
    0.2115
    $42.00
    10pcs. -- $31.50 per
    6G-0033
    6.366
    $45.00
    10pcs. – $33.75 per

    *Inches
    **Current pricing (subject to change without notice). Order Quantity/Discount per PO.

    Let me know if you need additional information.

    Regards,

    Cristin
    Service Department

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