Custom plastic parts

Discussion in 'The Projects Forum' started by ke5nnt, Sep 27, 2009.

  1. ke5nnt

    Thread Starter Active Member

    Mar 1, 2009
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    Has anyone ever needed custom plastic parts made for a project? How would you go about taking a design in your head and turning it into a custom plastic part for an electronics project without having/knowing CAD and that doesn't cost a ton of cash?
     
  2. miniengine

    New Member

    Sep 6, 2009
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    Could you be more specific as to what type of part?
     
  3. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    I make them myself on a toy lathe (Prazi) and HF miniature mill. If the design requires molding, then re-do the design. Anything requiring a mold is big $$ unless you make the mold yourself. Another alternative is e-machineshop.com.

    eMachineShop even has a free version of software that you can use with it.

    John

    Edit: Here's the correct link: http://www.emachineshop.com/
     
    Last edited: Sep 27, 2009
  4. rjenkins

    AAC Fanatic!

    Nov 6, 2005
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    Either find something similar and modify it or make it by hand.

    There is no other cheap, none-technical way.

    On the general subject, small quantities would probably be machined from solid or made using 'rapid prototyping (3D Printer) and large quantities by injection moulding.

    Thin plastic parts can sometimes be made by vacuum forming, which is possible to do as a DIY method.

    (So is Rapid Prototyping - see the RepRap project http://reprap.org/bin/view/Main/WebHome ).
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    Dremel is also your freind in this.
     
  6. someonesdad

    Senior Member

    Jul 7, 2009
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    The cost will depend on the type of part and how many of them you need. The usual home project needs one or a few, so making them by the usual technique of injection molding is not cost effective.

    You don't need CAD to communicate a design -- people have been making sketches with pencil and paper for a long time and it still works fine. You'll need some drawing skills though -- you can pick up the essentials by studying a drafting book. I do my layouts with a pencil, graph paper, drafting scale, and a couple of 30-60-90 triangles.

    If I need a custom plastic part, I try to design it so I can make it in my shop. Part of the "art" of design is in knowing what is easy to do in fabrication and trying to utilize only those elements in the design. The nice thing about plastics are that they tend to be easy to machine and some can be easily glued together (I like PVC and acrylic for that purpose). You can also use a plastic welder to join parts. Unfortunately, for the casual hobbyist, these things take money to buy and time to learn the skills. If you can find a friend who has the machinist skills, maybe you can trade something for his time. I often make one-off pieces in my shop with a hacksaw, chisels, files, and a rotary tool such as a Dremel. These are simple tools, but can take a long time to become proficient with. Most people don't have the patience to learn to use them.

    Casting is another fabrication possibility. If you can make a mold for the part, you can cast it in e.g. polyester resin.

    Unless you have a friend who will make the parts for you or you're willing to learn to make them yourself, probably your best option is to take a drawing to a local shop and ask for a quote. Be prepared to be stunned by how much it will cost.

    Since having a part made commercially ($50-$100 per hour for the shop's time) usually puts the cost out of the range of us amateurs, this forces us to cobble things together with parts we can get or make ourselves. Once you have such a need, you can start scrounging through the second hand stores, local hardware stores, etc. for things you can use. I view it as a challenge to find/adapt/make something for my needs -- and view the journey as pleasant as the destination.
     
  7. BMorse

    Senior Member

    Sep 26, 2009
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    You can try these folks >> http://www.bigbluesaw.com/ I have never used their service, but it seems to be what you are looking for....
     
  8. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    What glue do you use for acrylic? I glue larger thicknesses of acrylic (say 10mm thick clear perspex sheet) and have yet to find a glue that gives decent strength.
     
  9. rjenkins

    AAC Fanatic!

    Nov 6, 2005
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    The only thing I am aware of that truly bonds acrylic is Chloroform, which is rather nasty stuff to use & nowadays in some places places illegal to even posess.
     
  10. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Dichloromethane (DCM or methylene chloride) is a standard solvent bonding glue for acrylic.

    This is what I use: http://www.mcmaster.com/#weld-on-adhesives/=3thjoq
    Weld-On #3 Very fast set
    Weld-On #4052 Slower set

    TAP Plastics may have smaller quantities available. TAP also has instructions for acrylic bonding. For good bonding you want sanded, not polished surfaces and a tight fit. There are thick solvents that can fill in less than perfect fits.

    Ken
     
    Last edited: Sep 28, 2009
  11. ke5nnt

    Thread Starter Active Member

    Mar 1, 2009
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    Thanks for all the suggestions. I'll look into those links and other ideas.
     
  12. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Yes, thanks for the info, i'll check into that. I haven't seen Weld-on brand locally but someone probably stocks it here in Australia.
     
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