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Thread: 3d Printing Greensand Lost PLA Mold making

  1. #1
    Boolit Buddy

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    3d Printing Greensand Lost PLA Mold making

    I have been reloading for a few years now. 3d printing for about 6mo and learning CAD. I was wondering if anyone on this board had any experience with 3d printing a mold in plastic, and then using a Lost PLA method to cast it in aluminum using greensand. I would like to try a roundball mold in the near future and just thought I would look for advice or tips if any have done it before me. Thanks in advance for any advice or leads on resources.
    "Failure to prepare is preparing to fail" - Benjamin Franklin

  2. #2
    Boolit Master Scrounge's Avatar
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    I have not done it, but associate with folks who do all sorts of related stuff https://groups.io/g/3D-Printing-for-Metal-Hobbyists this link was posted on that group: https://www.youtube.com/watch?v=cvi8A2XCK94 If you search lost PLA at youtube you'll find more info. There is at least one where they use a fluidized sand bed using a vacuum cleaner as a blower to agitate silica sand to sink a PLA model in, and use the molten metal to burn it out. It can be a very interesting rabbit hole to jump into!

    good luck!

    Bill <---still needs to excavate his 3D printer from a pile of stuff...

  3. #3
    Boolit Buddy

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    Sir that is an outstanding video and of course lead me on to other good ones. I appreciate it.
    "Failure to prepare is preparing to fail" - Benjamin Franklin

  4. #4
    Boolit Master Scrounge's Avatar
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    Quote Originally Posted by psychicrhino View Post
    Sir that is an outstanding video and of course lead me on to other good ones. I appreciate it.
    this one looks pretty good, too! https://www.youtube.com/watch?v=zS382O2bP0M

    Bill

  5. #5
    Boolit Grand Master

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    Why not just 3D Print boolits ...

    Is CAD ... Computer Aided Drafting
    Certified Cajun
    Proud Member of The Basket of Deplorables
    " Let's Go Brandon !"

  6. #6
    Boolit Buddy

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    You could but they would be plastic.
    "Failure to prepare is preparing to fail" - Benjamin Franklin

  7. #7
    Boolit Grand Master

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    Look for Tubalcains 222 videos on you tube. he does some aluminum casting using printed parts for doing the cope and drag with green sand casting. It is a much easier way than making to old wood forms.

    I would consider the lost wax method of casting making a wax form coating with clay and melting the wax out then filling. Finish is better and its more precise.

    The sand is a lot of work in itself getting it to the right mix with the additive to where it packs right, grading it in a muller to the desired grain sizes making the cope and drag to the size needed filling and packing in tight enough to hold the form in handling. cutting the gates vents and fill holes. A sand mould is normally 1 time use also.

    I would consider printing the 3d mould making wax forms dip to an appropriate thickness in a clay slurry harden and fire on the pot melting the wax out then fill.

  8. #8
    Boolit Master Scrounge's Avatar
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    Quote Originally Posted by country gent View Post
    Look for Tubalcains 222 videos on you tube. he does some aluminum casting using printed parts for doing the cope and drag with green sand casting. It is a much easier way than making to old wood forms.

    I would consider the lost wax method of casting making a wax form coating with clay and melting the wax out then filling. Finish is better and its more precise.

    The sand is a lot of work in itself getting it to the right mix with the additive to where it packs right, grading it in a muller to the desired grain sizes making the cope and drag to the size needed filling and packing in tight enough to hold the form in handling. cutting the gates vents and fill holes. A sand mould is normally 1 time use also.

    I would consider printing the 3d mould making wax forms dip to an appropriate thickness in a clay slurry harden and fire on the pot melting the wax out then fill.
    That users name is Mr. Pete222, and he goes by Tubalcain. He gets little love for that in the model engineering fraternity, since that was the pen-name of a prolific writer in the UK's Model Engineer magazine back in the post-war years. Never the less, Mr. Pete222 is a great resource! https://www.youtube.com/results?sear...ry=Mr.+Pete222

    Green sand is good for some things, the clay thing (once upon a time, they mixed cow or horse manure into the clay to make the molds less fragile) is also good some things. Some folks used cuttlefish "bones" to make molds, and jewelry makers use a slurry of refractory mix to make lost-wax castings in precious metals. It's good to have all the various techniques in your arsenal. I've got books! Lots of them! Various metals have different shrink rates, so you need to know what the shrink rate for what metal you're casting is in order to get the dimensions right on the finished casting. Read some of the old books on foundry work at Archive.org and you'll find that they made "Shrink Rules" scaled to use with iron, brass, bronze, aluminum, etc., to help in getting the pattern pieces made. I've been looking for a pattern-maker's square for several years (that I could afford) as I wanted to make patterns for the vise that goes with my Lewis Shaper, since that company has been out of business since about 1957. Vintagemachinery.org found and uploaded a copy of the drawings for the for the shaper vise, so now I have dimensions.

    Now all I gotta do is learn how to use a CAD program myself. YIKES! I flunked Mechanical Drawing in 1969 or 70, IIRC. Just downloaded and installed Solid Edge, supposedly has great tutorials, IF I can get to them. And remember all this stuff about shrinkage, etc. Though I won't have to worry about draft if I 3D print the pattern and do some sort of lost plastic casting... Fluidized sand bed sounds like just the ticket!

    Bill
    Last edited by Scrounge; 06-25-2022 at 10:40 AM.

  9. #9
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    Thanks gents for all of the thoughtful replies. I continue ti check back here for insights shared as I look gorward to another long alaskan winter if projects.
    "Failure to prepare is preparing to fail" - Benjamin Franklin

  10. #10
    Boolit Master Scrounge's Avatar
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    Quote Originally Posted by psychicrhino View Post
    Thanks gents for all of the thoughtful replies. I continue ti check back here for insights shared as I look gorward to another long alaskan winter if projects.
    I've got this book in hardback, had it since I was a young pup. It's good for Jewelers, and folks who want to make detailed models. https://www.amazon.com/Creative-Cast.../dp/0047300019

    Got a local friend who has another company investment cast his models in stainless steel, among other things, for model railroaders. I believe he mostly uses waxes, but there are machinable and castable waxes, as well. And recipes to make your own from scratch. He's a wiz with SolidWorks, and may be doing 3d-printed models for some of his parts.

  11. #11
    Boolit Grand Master uscra112's Avatar
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    The very first use of what is now called 3D printing that I ever saw was being done at Pratt & Whitney. They were forming the wax patterns for a complex turbine blade by what they then called stereolithography. That was a good 30-40 years ago. Wasn't done with filaments like today, they used as laser to melt and fuse the shape sitting in a "bath" of powdered wax. building up layer by layer.

    So it's come full circle.

    Also years ago, we made patterns of styrofoam instead of wax for the "lost foam" method of making machine tool castings.
    Cognitive Dissident

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