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Another 3D printing conundrum with a segway into casting bronze

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  • #16
    This is normal, 3D printing has thousands of variables that need to be in balance, while the printer itself is an ever changing variable with wear and tear.
    Resin printers have their own set of challenges but I find them to be more reliable and much higher detailed. I bet they make a resin for casting. The printers themselves are also much cheaper. Material handling is a pain in the ass though.

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    • #17
      Probably, they do make special filaments for casting, most likely pricey and intended for industry but I don't want to invest money in something I would only use a bit. My friend that does the casting is very good (professionals should be so good) at sand mold style casting. he has played around with lost foam casting but has had mixed results.
      The shortest distance between two points is a circle of infinite diameter.

      Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

      Southwestern Ontario. Canada

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      • #18
        I reprinted the same part today with grid infill and I cut the retraction back to 5 from the Cura standard of 6.5 and the print went OK. How long will it last..............................fingers crossed. Oother then this one thing the printing is going well with reasonable quality. Good enough for the people I date.
        The shortest distance between two points is a circle of infinite diameter.

        Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

        Southwestern Ontario. Canada

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        • #19
          LN, Check out filaments.ca, they are local to us and have a good selection of various filaments including for casting, I have had nothing but good experiences with them.
          I found the trick to printing lightweight airplane parts with minimal infill was increasing the number of perimeters or outer layers, try it at 4 or 5 perimeters.
          Cheers,
          Jon

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          • #20
            OK thanks.
            The shortest distance between two points is a circle of infinite diameter.

            Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

            Southwestern Ontario. Canada

            Comment


            • #21
              Originally posted by Dragons_fire View Post
              ive also played around with lost PLA. Im using an old pottery kiln to do the burn out and just regular plaster of paris for the mold. i start low, about 150*F for a couple hours, then up to 300*F for another 2 hours and then start bumping it up 100*F an hour until I hit 900*. Then straight out and into a bucket of sand and i pour the aluminum in.

              I havent put much effort into refining things, but i got ok results on simpler parts. I put the mold in the kiln upside down, and when a lot fo the PLA melted out onto a tray, i would take the tray out. Im not sure if its the PLA, PoP or something else remaining in the kiln, but it smells really bad and makes my eyes water when the temp gets higher. I think its the acid in the PLA, but couldnt stand it, so I havent done much more since.

              Plaster of paris also gets fairly brittle at those high temps, so I wasnt getting very consistent results with small details that i was playing with. I tried making some model engine blocks with water cooling, and the passages would fill with plaster, but the plaster would break and move around inside the molten aluminum and wreck the part.

              thats all thats coming to mind right this minute. If i think of any other details i will add them later.
              I used to own a small bronze foundry and my investment recipe was about for every five pounds of plaster add a cup of sand and a half cup of chopped glass. I would warm the mold at about 180 degrees F for a for a couple of hours to dry out the mold and raising it to 250 and bake a little more before going to full temp. This whole operation was to prevent the mold from cracking. Also my mold flasks were made of chicken wire and tar paper.

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              • #22
                Is that silica sand or will any sand (children's play sand) work also. I have ground glass I use in my blaster, fairly fine. Will that work, I'm guessing not??? I do have a manual burn out furnace, no ramp controller, good to about 1600F.
                The shortest distance between two points is a circle of infinite diameter.

                Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

                Southwestern Ontario. Canada

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                • #23
                  The solution to this was simple, if a bit belated. The hot end was jamming up because the print temp. was to high, heat creep up the separator making the filament soft and sticky. After I lowered it 10 deg it is fine. I also lowered the bed temp to 50F and used glue. Now bed adhesion is not a problem. The temp sensor on these 3D printers can be off quit a bit (10% either way) and I believe mine was running a lot hotter then it was set to.
                  The shortest distance between two points is a circle of infinite diameter.

                  Bluewater Model Engineering Society at https://sites.google.com/site/bluewatermes/

                  Southwestern Ontario. Canada

                  Comment


                  • #24
                    Originally posted by Dragons_fire View Post
                    ive also played around with lost PLA. Im using an old pottery kiln to do the burn out and just regular plaster of paris for the mold. i start low, about 150*F for a couple hours, then up to 300*F for another 2 hours and then start bumping it up 100*F an hour until I hit 900*. Then straight out and into a bucket of sand and i pour the aluminum in................................................ .................................................. .................................................. ..Plaster of paris also gets fairly brittle at those high temps, so I wasnt getting very consistent results with small details that i was playing with. I tried making some model engine blocks with water cooling, and the passages would fill with plaster, but the plaster would break and move around inside the molten aluminum and wreck the part.............................................. .................................................
                    Warning !
                    You have to watch investment or investment plaster. You should take it to 1200 to 1300 and hold it for at least 20 minutes .
                    At about 1100 the investment changes to a type of ceramic and releases water (yes at 1100 F) It could be that is what is destroying your pour.
                    I know it did for me several times until I understood the phase change that occurs.
                    Books on casting are wrong---because they call it a "Wax burnout temperature" but I had no wax in the mold and poured at 11-1200 with failures !
                    The hot metal causes the moisture to turn to steam and that breaks internal passages
                    Found out why the 1300 is needed, but the name for it is bogus - Its a needed temp to complete the phase change of investment ...be aware
                    Rich

                    Green Bay, WI

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