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Re: [casting] Casting Media

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  • Ray K
    I am not a plastics expert either, but this is surely confusing some here. The polyurethane resins that 99.9999% of us use here ARE plastics as well. By
    Message 1 of 13 , May 7 9:23 AM
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      I am not a plastics expert either, but this is surely confusing some here.
      The polyurethane resins that 99.9999% of us use here ARE "plastics" as well.


      By definition, plastic is: "Any of various compounds produced by
      polymerization, capable of being molded, extruded, cast into various shapes
      and films, or drawn into filaments used as textile fibers". With only a few
      exceptions (vacuum-forming is one), none of us will ever get
      into thermoplastics unless we actually work in that field.

      There are 2 "basic" types of plastic that most of us know about;
      Thermoplastics (the kind that you heat to melt) and Thermosets (the kind
      that create their own heat by reaction).

      Generally speaking, with a few exceptions, you and I will never use
      thermoplastics (ABS is one) in our business/hobby of casting since MUCH
      better and more complex results can be had from our thermoset resins such as
      polyurethane.

      THAT is why "casting your own" has become SO popular in the last decade;
      more user-friendly and less costly molding and casting products have come to
      the end-user: WE people on this list. Certainly the list also includes
      metal-casting, but by and large, I would bet 90% of the members of this list
      are (thermoset) resin casters...

      On Thu, May 7, 2009 at 12:00 PM, Charles Dean <tank.cars@...>wrote:

      >
      >
      >
      > Surely someone on this list will know a lot more about plastics than me,
      > however....
      >
      > High temps are necessary to liquefy plastics. The temp can be critical as
      > plastic easily burns. Liquefied plastic is not as viscous as resins at room
      > temp. I don't think any of the molds we create for room temperature molding
      > will be useful for working with plastics. Plastics are typically melted and
      > injected, under pressure, into a mold.
      >
      > I wouldn't be at all surprised if there is a yahoo group for such
      > interests.... look for plastic injection molding. Or search on Google and
      > get yourself a plastic molding machine. And unless you need hundreds or
      > thousands of a casting, don't forget to consider rapid prototype modeling.
      >
      > Charlie
      >
      > Charles Dean
      > Shelbyville, Kentucky
      > ----- Original Message -----
      > From: grizgrin
      > To: casting@yahoogroups.com <casting%40yahoogroups.com>
      > Sent: Wednesday, May 06, 2009 3:17 PM
      > Subject: [casting] Casting Media
      >
      > As I have read and tried to educate myself about casting, pretty much All I
      > hear about are resins ans white metals. Does anyone use plastic? Would it be
      > possible to melt down some plastic (presuming you buy the "right kind") and
      > pour tha tinto a mold as opposed to using a resin? Does anyone on here do
      > this, and if so what can you share about your knowledge, experiences? How
      > does it compare to resin for set times and such?
      >
      > [Non-text portions of this message have been removed]
      >
      >
      >



      --
      Ray Kotke
      www.telephonecreations.com


      [Non-text portions of this message have been removed]
    • Jeff Acker
      I found this web site awhile back that sells bench top plastic inject machines and supplies. I have never bought anything from them so I can t vouch for the
      Message 2 of 13 , May 7 6:58 PM
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        I found this web site awhile back that sells bench top plastic inject
        machines and supplies. I have never bought anything from them so I can't
        vouch for the company or there products. But you can kind of see what the
        process is like. and what you need to get into plastic injection.

        http://www.iasco-tesco.com/

        Jeff
      • Richard E Bendever
        Yes, I wrote the article in the 1996 Nov/Dec Narrow Gauge & Shortline Gazette using a hot glue gun as an injection apperatice and the pros/cons of the various
        Message 3 of 13 , May 8 8:56 AM
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          Yes, I wrote the article in the 1996 Nov/Dec Narrow Gauge & Shortline Gazette using a hot glue gun as an injection apperatice and the pros/cons of the various glue sticks and the process. Now that this issue is out of print but I have permission to re-release my article. I am currently working on an follow up to the technique. If you have any interests in knowing more please feel free to contact me off-line at rebendever @ debenllc . com (without the spaces).
          BTW What led me to the above was the Make-It-Bake-It Beads (another Gazette article) technique where after a RTV mold is created the commeically produced beads we placed in the oven about 450 degrees for 25 minutes and the melted pile of plastic beads 'slumped' into the mold. Didn't work for the kind of detail that I was looking for and really stunk up the kitchen. But that's another article.
          DEBEN LLC ================ Richard E. Bendever
          www.DEBENLLC.com | - Doctor Ben's Scale Consortium | Fine Scale Miniatures Biz | Main Street Motor Co | Smoky Mountain Model Building | Ph.: 770.979.5069

          --- In casting@yahoogroups.com, Greg Krynen <scorpiodragonk@...> wrote:
          ... > I have heard some people use a hot melt glue gun and thermoplastic rods or the glue itself and small molds to 'inject' pieces. But these are generally small (read tiny parts). Though a double boiler might obtain the proper temperature without a direct heat 'flame out' of the material to do bulk pour. Be advised the mold would have to be heated as well to prevent the goo from cooling too fast and causing a partial fill of the mold.
        • Cindy Carter
          I regularly buy from this company, so I am familiar with them. They mostly sell to schools, art departments, shop class and such. They are a small company but
          Message 4 of 13 , May 8 5:47 PM
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            I regularly buy from this company, so I am familiar with them. They mostly
            sell to schools, art departments, shop class and such. They are a small
            company but offer a lot of hard to find products in the thermoforming
            market. They will send you a catalog, which also has some good tips.
            Cindy
            www.resinobsession.com
            On Thu, May 7, 2009 at 8:58 PM, Jeff Acker <verso2@...> wrote:

            >
            >
            > I found this web site awhile back that sells bench top plastic inject
            > machines and supplies. I have never bought anything from them so I can't
            > vouch for the company or there products. But you can kind of see what the
            > process is like. and what you need to get into plastic injection.
            >
            > http://www.iasco-tesco.com/
            >
            > Jeff
            >
            >
            >



            --
            Best Wishes,
            Cindy Carter
            713-598-0330
            www.resinobsession.com
            http://stores.ebay.com/resinobsession?refid=store
            http://resinobsessionblog.blogspot.com/
            www.resinobsession.etsy.com
            www.youtube.com/user/FunkyTreasures


            [Non-text portions of this message have been removed]
          • Steve
            It is somewhat the consistency of clay or soft wax when heated. If this is the same thing sold as Friendly Plastic , be aware it is only good for temporary
            Message 5 of 13 , May 9 6:28 AM
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              It is somewhat the consistency of clay or soft wax when heated.

              If this is the same thing sold as "Friendly Plastic", be aware it is only good for temporary use. Friendly Plastic gets very brittle and crumbly in a few years, regardless of whether it is used or not, and reheating it does not renew it.

              Leave it in your car on a hot day and it will melt into your upholstery.

              Steve Greenfield

              --- In casting@yahoogroups.com, "Andrew Emmerson" <andrew.emmerson4@...> wrote:
              >
              > There is Polymorph (http://www.mutr.co.uk/product_info.php?products_id=550&osCsid=8956bae37203aa52dfcb6bcd35293ba5) available at all Maplin Electronics shops.
              >
              > It is clever stuff but you cannot pour it. Nevertheless it obviously suits some people's needs.
              >
              > Worth looking at to see if it will float your boat.
              >
              > Andy Emmerson.
              >
              >
            • lmshutt@hiwaay.net
              ... I have bought sheet styrene (listed under the vacuforming section) from them a couple times and had no complaints. If you use a lot of plasticard they are
              Message 6 of 13 , May 9 8:52 AM
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                On Fri, 8 May 2009 19:47:29 -0500, you wrote:

                >
                > http://www.iasco-tesco.com/


                >I regularly buy from this company, so I am familiar with them. They mostly
                >sell to schools, art departments, shop class and such. They are a small
                >company but offer a lot of hard to find products in the thermoforming
                >market. They will send you a catalog, which also has some good tips.
                >Cindy

                I have bought sheet styrene (listed under the vacuforming section)
                from them a couple times and had no complaints. If you use a lot of
                plasticard they are much cheaper than the local hobby shop.

                --
                Lane
              • grizgrin
                Wow. Thanks for all the info. I left this thread for a few days and it s blossomed all KINDS of useful stuff. I really appreciate all the input, even the
                Message 7 of 13 , May 10 1:58 PM
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                  Wow. Thanks for all the info. I left this thread for a few days and it's blossomed all KINDS of useful stuff. I really appreciate all the input, even the digressions have been useful since they touch on subjects I work with. Thanks all!
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