3D Printer adapted to cut PolyStyrene Lost Foam Patterns

Discussion in 'Lost foam casting' started by Al2O3, Jun 26, 2022.

  1. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I saw this in the course of another search and thought it was interesting and may have some merit for making lost foam patterns.



    In short, the author replaces the filament extruder with a heated rod which is used to evaporate the foam using an adapted 3D printer. The fist 15-16 minutes is about the printer mods and the last couple minutes are the results.

    The first thing that came to my mind, this is essentially wire EDM machining. Now I could do the exact same thing on my CNC router with CAM software, and assuming similar surface finish was possible (not at all sure about that), basically would be trading foam dust and noise for odor from the evaporated foam, which is fairly easily dealt with, but the idea that you could take a relatively inexpensive 3D printer and use it as 3D motion control for making an LF pattern while still preserving its ability to be used as a 3D printer seems like it could be very useful and practical tool for the hobbyist.

    One of the first things that occurs to me is 3D printing is additive while this method is subtractive. The author says he is clear about gcode mods in the video but I'm not so sure about that. Perhaps some of you 3D printer guys can chime in on that. Software manipulation to slicer programs would add some complexity.

    One thing I can say from my experience with foam, when you cut with a hot tool, Like all other maching, it's all about feed and speed. Cutting surface speed in this case is heat. You need to get the heat and feed rate carefully tuned, or the foam will have an uncontrolled kerf size and will also be densified at the cut surface which would be undesirable for a LF casting pattern. However, with the right feed and speed, you can get a nice result. This is easily observed using a hot wire cutter.

    At the end of the video he performs what appears to be a full depth cut of a surface. I could see how having different roughing and finishing tools might be useful.

    Best,
    Kelly
     
    Monty likes this.
  2. Monty

    Monty Silver

    This is definitely worth playing with since I already have the hardware. Marlin firmware just reads G code, so all you need to do is add some lines specific to the printer to any G code file. Speeds and feeds should be fairly easy to work out.

    What about a hot drag knife? You could cut down to the contour depth, break out the foam "slivers" Then use a finish tool.

    Whether the surface finish on EPS will be good enough???? IDK.

    Monty
     
  3. Smoking Shoe

    Smoking Shoe Silver

    Rabbit holes often have some interesting rooms.............

    18+ minutes of cheesy music for info that could be presented in about 3 minutes. o_O
    Love the ingenuity of the home made mini lathe. :cool:

    Using Marlin for CNC is apparently quite possible. I have a box of parts for a small CNC that includes a 32 bit board that I intend to set up with Marlin 2.0/MACH 3.
    Probably a winter project.
     
  4. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    I have to confess, I only actually watched about two of the first fifteen minutes and skipped right to the result. Completely missed the lathe.

    I thought it was interesting for the reasons stated, but for me, I'm not sure there is any advantage compared to a CNC Router. I have the dust under control. I could do without the noise but not at the expense of accuracy or quality of the pattern. Having thought about it and comparing the two:
    1. Don't know how speed of cut would compare, but build up of PS on the heat cutting stylus could become an issue. My guess is the two might be comparable with a high heat roughing operation for the evaporative approach, at the high risk of unintended local over-evaporation of the pattern.
    2. I'd have to think a CNC router would be more dimensionally accurate. It's a function of your machine but even for my hobby machine it's within a couple thousandths over two feet. Cutting foam is an easy chore. I don't think you'd get to that accuracy with evaporated kerf control.
    3. For surface finish, it's hard to say, but with either, I'd expect light sanding work for the finishes I desire.
    4. I'm not experienced with the 3D printer slicer software, but the waterline 3D machining ops must be very similar. It slices the part as if you were draining water out of the work space. The cuts are just ordered from top down instead of bottom up for printing.
    5. My current cnc workspace is 36x36x4 right out of the box and I use most of that work space for the parts I make. In fact, I'll be adding more (probably doubling) z-axis. Most 3D printers have much more modest work space envelop.
    But like I said, if you already have a 3D printer and experience with it, not having the noise and dust in a household vs shop environment, it may make sense for an occasional lost foam pattern.

    Best,
    Kelly
     
  5. Tops

    Tops Silver Banner Member

    The MacGyver lathe was cool!

    I originally though I was going to adapt my 24 x 24 x 3" hobby gantry CNC to do 3D printing and laser and drag knife to add capability and reduce footprint.
    Instead, I took the upgrade money and bought a separate printer followed by a separate laser, both which set up and worked right out of their boxes. It takes up more space but there is no development or changeover time and some days I run more than one at the same time.
    It seems like machining XPS would be a finer finish that a heated ballnose type 'melter' could do making stringers.
    I have hot wired billet EPS up to 12.5 feet long and 3 feet wide using Masonite templates and a bow with a tension spring for the wire and a variable power supply.
     
  6. BattyZ

    BattyZ Silver Banner Member

    You said it all right there! Love dedicated machines, as long as you can keep them moving. Having the machines setup and ready also entices the umm..unmotivated person to get going lol
     

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