Maxsurf Model to 3D Printer

Discussion in 'Software' started by alexjblake, Mar 29, 2016.

  1. alexjblake
    Joined: Mar 2016
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    Location: Glasgow

    alexjblake New Member

    Hello,

    This is my first post so quick introduction, I'm currently in my 4th year at University doing Naval Architecture and a long time boat lover!

    I'm currently doing my dissertation on the optimisation of offshore lifecraft and I'm using the Bentley Maxsurf suite of software to do it. I've just about finished the design aspect of it and thinking ahead to the presentations etc.

    Recently I got a 3D printer and had the idea to print the design I have come up with in 3D as a visual and tactile model to hand round but was looking for some advice with the conversion from Maxsurf Modeller to MakerBot...if anybody has any experience.

    I've got the STL file into Makerbot fine but the preview doesn't look right (Image attached).

    Does anyone have any ideas how to get the printer to print just the Hull Form without heavy infill or loss of structure at the bow? I've tried exporting it to Inventor to see if that would yield anything better but can't get that to act as a solid

    Thanks in advance,

    Alex
     

    Attached Files:

  2. bhnautika
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    bhnautika Senior Member

    Hi alexjblake welcome to the forum. The STL file had some issues with mixed surface normals, some going in, some going out they need to all be in the same direction. To get some wall thickness to the shell so the hull is not a solid lump you could take it into a programme like blender (free) and add a “solidify modifier” to the mesh which will give you any thickness you want. To get accuracy in shape from a nurbs based model to a mesh based you will need to be able control the mesh output to increase its density to closer fit the surface model.
     
  3. ludesign
    Joined: Aug 2003
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    ludesign Senior Member

    As pointed out, the so called normals are partially inverted. Do you have a feature for reversing normals in your program? Most Solid modeling CAD programs have it, and my hull fairing program TouchCAD has it. Other problems is that the model leaks, that is the panels do not fit edge to edge properly. It also lacks a bottom, which is fundamentally required to generate a solid shape. It must be a truly closed volume. You can of course just add a bottom panel, though it would then generate quite a lot of volume. An alternative method would be to use a program that can generate a "shell" operation, which essentially adds a thickness to the the hull panels. The model would then be hollow, which generates another problem, you need to support the shell with something while building. This can be done if you have a printer with two extruders, where one produces a disposable material, for example a material that can be dissolved in water.
     
  4. alexjblake
    Joined: Mar 2016
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    alexjblake New Member

    Thanks for the replies above!

    I will have a look at the surfaces again in Maxsurf and insure that they're all going the same way when it comes to exporting, I haven't found anything in Inventor to invert them but I'm sure with some hunting or a look into TouchCAD I'll be able to figure something out.

    I've currently got Blender downloading so maybe tonight I will try the solidify modifier and see what it thinks of that.

    I happened to see the dissolveable filament the other day when looking around and couldn't for the life of me think why that would be useful but I can absolutely see ease of using that as a support/raft material and then having it dissolve away afterwards! I've got a dual extruder so I may try that when it comes to the final print!

    Thanks for your help, I will keep this updated with my progress!

    Alex
     
  5. ludesign
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    ludesign Senior Member

    Most print programs allow you to flip normals on surfaces. Check in your printing program. If you spin it a bit it becomes obvious where it goes wrong. This is what it looks like in Simplify 3D. You are supposed to see outside panels from any view.

    There are also many utility programs that allows you to analyze normals, so it should not be much of a problem anyway.

    Note that you can clearly see leaks in the picture. You should fix that too. It is unfortunately a common problem in many NURBS based program.

    If you have access to Inventor, I would try exporting to that instead of Blender, which really isn't a CAD program at all. The 3D engine is much better and adding a shell is more reliable in more high end engines. Rendering programs do however use normals too, essentially to keep track of what to be visible or not and to control textures.
     

    Attached Files:

  6. bhnautika
    Joined: Feb 2006
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    bhnautika Senior Member

    Alexjblake when you modelled the hull in maxsurf did you bond edges or do any trimming? Also how did you export out and in what format? The meshing is different on different surfaces so their edges will be different.
     

  7. formsys
    Joined: May 2007
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    formsys formsys

    Here are some tips for the model in Maxsurf -
    Make sure the model is closed (eg add a deck if there isn't one already)
    Where possible Use surface bonding to join surfaces together
    Make sure all the surface models point outwards (Outside Arrows in the Display menu)
    Preparing a model for STL is much the same as preparing it for stability (also requires a watertight volume). See the first part of the following video for guidance on doing that
    https://youtu.be/f08F1XNtW_s
     
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