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  1. #1

    advanced 3d printing idea - need help

    hi, I'm new to the forum, just bought a 3d printer because I had the vision of 3d printing wax models and investment casting them, in my head this was a quick way to produce cast parts for prototyping quickly, but it didn't really match with what these printers are capable of. My background is in machining, I now own a shop with a bridgeport, rockwell lathe, harig surface grinder, haas vf-2 with 4th axis, haas tl-1, and am generally in the field of helping companies finalize designs by getting a working part out very fast for testing. I have used the printer a couple times to make simple parts which were then used to make bonded sand molds for casting, but for the really advanced stuff I want to do, I think what I need is something that can print binder into sand, to build a sand casting mold directly. this would allow for some really interesting capability, in that certain molded features would be almost impossible to do with conventional methods.

    Here's where I'm at.

    I purchased some larger steppers, drivers and power supplies, and have an extra arduino controller from my ft-5, in my head what I'd like to figure out how to build would be basically an inkjet print head that would print a binder onto a sand layer in a co2 atmosphere, the binder reacts with the co2 and hardens, allowing for deposition of the next layer. I believe I could use fuel injectors as the control valves for each nozzle in the head, since they're designed to be used at high pressure and switch at very high speeds. building the hardware will be, well, a no brainer for me, because that's what I do all day. Developing the software, however, would be a challenge, since I really don't have the time to learn all the intricacies of turning an stl file into a surface slice, then into a bitmap, then into instructions for the print head, is there anyone here who really likes to play with software or someone who has already built a printer like this?

    p.s. I know they're commercially available, but I'm not sure what the immediate return on a machine like this would be, so I'm not comfortable with diving in if I could build one and figure out if there's a good market for its use

  2. #2
    Super Moderator Roxy's Avatar
    Join Date
    Apr 2014
    Lone Star State
    Would it make sense to put a nozzle on the printer that can extrude wax? And you would then just print the wax object as if it was plastic?

  3. #3
    Join Date
    Jul 2017
    Printing a binder onto sand would work pretty similarly to SLS printing. HP also have a line of printers that print a binder onto a powder medium to create parts. Not sand in this case but same basic concept.

    The problem I see here is that this method is that you would end up with a mold that's full of sand. Parts produced by SLS and HP's printers are not hollow, they are full of the unbound or unsintered powder. Investment casting or similar with regular PLA/wax FDM printing is probably your best bet. If you've got money to burn take a look at SLM (not SLS) or some of the newer machines that use metal powder with a plastic binder in what's more or less an FDM 3d printer, then sinter the printed parts in a kiln to produce metal parts.

  4. #4
    true the mold would be surrounded and full of unbound sand, but molds also need a large sprue, risers, vents, if the metal has to go in somewhere, then the sand would by definition have a path out

  5. #5
    Staff Engineer
    Join Date
    Jan 2014
    Oakland, CA
    As you mention, machines like this are commercially available, but costly. If I wanted to build one, I'd be tempted to start with an old Z-corp machine, which already has the mechanism for laying down powder in thin layers. You'd have to hack the controller, though, to use your own dispenser - there's no way the thick sodium silicate binder would go through the printheads they use. While it's true that the sand could flow out through the same channels as the metal flows through, it would take some attention in the design process to make sure none would be trapped in undercuts or blind passages.

    Given the expense and complexity of all that, if I were you, I'd give serious consideration to simply using a standard FDM machine to print your parts a little oversized in PLA, which burns out pretty well, and using the lost-wax process to cast near-net parts which you can then machine to final tolerances. For a little more money, you could get a SLA or DLP resin printer and use material designed to burn out cleanly. That would give you better surface detail to start with.

  6. #6
    Nice discussion is going on. 3D printing is really the best idea to represent own thoughts with quickly & practically. There are so many companies which providing 3D printing service. But mostly I prefer Iannone 3D for this. Their techniques are really good & so advance. They providing all types of 3D prints at an affordable price.
    Thank you
    Last edited by dannielgery; 12-08-2017 at 08:29 PM.

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