Hi all, new here with a quick question

Discussion in 'Newcomers Lounge' started by Hacksawbob, Jan 5, 2013.

  1. Hacksawbob
    Hacksawbob New Member
    Well not exactly new I've been lurking for quite a while. Even though I'm really exited by the possibilities of 3d printing I'm finding really hard to get started. even the most basic shapes I seem to struggle to get anywhere with. Anyway after much googleing and youtubing I have a simple hollow dome completed. It's about 20cm Dia and 10Cm high but it's coming in at $429 in strong and flexible! Have I messed up somewhere or is this what it really costs?

    http://www.shapeways.com/model/856512/dome.html?li=productBo x-search

    I have made it public I hope you can see it.

    Attached Files:

  2. mkroeker
    mkroeker Well-Known Member
    I have not checked the dae file, but from the model render the wall looks to be much thicker than 1mm, so you
    may be able to save some volume there.
    In any case, 3d printing will not be an efficient method for a rather big but simple plastic bowl. Compare e.g. this object from henryseg's shop - probably still somewhat smaller volume than your dome and I doubt he has added excessive markup on top of the basic cost of printing.
  3. Hacksawbob
    Hacksawbob New Member
    Thanks, it was a template for something else just to get an idea of cost, the wall is about 10mm thick for strength as it would have some pressure put on it in its intended application.
  4. mkroeker
    mkroeker Well-Known Member
    Cost in the cheapest version (white nylon, usually referred to as WSF - white,strong,flexible here) is 1.50$ per cubic centimeter
    (ignoring the discount for larger objects for now, as I have not checked if it would apply). Volume of your model is roughly:
    (half the volume of a sphere of 10cm radius)-(half the volume of a sphere of 9.8cm radius)
    assuming 2mm walls, volume of sphere is given by 4./3.*Pi * r^3
    so no, it will not be exactly cheap...
    Also note that the sintered plastic is porous, so probably not suitable to contain any pressurized fluid without considerable
    post-processing. (If you look in the "blog" section of the site, there were some microscope images/videos of the material
    posted sometime around october last year)

    EDIT: If you mean mechanical pressure, building a rib structure instead of a solid shape (or a thin solid with thicker load-bearing ribs) should lead to a significant cost reduction.
    Last edited: Jan 5, 2013
  5. Hacksawbob
    Hacksawbob New Member
    It is mechanical pressure, with stretched material to be overlaid and pinned into the dome as it acts as a form. I made the walls 1Cm thick would 2mm have any significant strength?
  6. mkroeker
    mkroeker Well-Known Member
    I cannot really answer that, as I have not created any similar (nor any load-bearing) parts myself. The 2mm was just an estimate (based on the design guidelines for "larger" objects as given on the materials info page) for something that should not bend under its own weight during printing. If nothing else, it should give you the lower bound for the cost of your part and you could reinforce it with a ribbed or even geodesic outer structure while staying below the $400 figure for your massive first model.
  7. Hacksawbob
    Hacksawbob New Member
    OK thanks for all your help... back to the drawing board then! :)