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Thread: Lightwave > Replicator G Scaling issues

  1. #1
    Pixel Flipper kvanover's Avatar
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    Lightwave > Replicator G Scaling issues

    So I bought a Makerbot-Replicator 3D printer, and I've been trying to print using my lightwave objects.

    Lightwave > Stl Exporter Lscript
    or
    Lightwave > Export to OBJ

    However there are some serious issues with scaling. If I make a 1 inch cubed block. Export the cube to Stl or Obj (or any other format). The resulting object is so small in replicatorg that you have to scale it a number of times just to get it to appear on the stage. And of course once you've done this there is no way to tell the actual dimensions of the object.

    Has anyone else run into this? If so have you come up with a solution?

  2. #2
    Look around for cad to LW scaling info.
    The one's I found said 100:1 for getting similar sizings.

    A suggestion:
    Make 4 boxes, scaled 4x at four different levels. Put those in as the object to be printed and you should have a better idea of what size you need to use as your standard.

  3. #3
    Pixel Flipper kvanover's Avatar
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    Quote Originally Posted by UnCommonGrafx View Post
    Look around for cad to LW scaling info.
    The one's I found said 100:1 for getting similar sizings.

    A suggestion:
    Make 4 boxes, scaled 4x at four different levels. Put those in as the object to be printed and you should have a better idea of what size you need to use as your standard.

    Thanks, I'll poke around and see what I can dig up. And thanks for the suggestion as well. I'll post any solutions I find.

    KV

  4. #4
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    The internal unit of measurement for a LWO file is the meter.

    When LightWave displays the units in inches on the screen that is for the convenience of the user only. When you make a one inch cube it is converted to its metric equivalent which is 0.0254 meters.

    When you export to STL or OBJ file your one inch cube is written as 0.0254 meters and that is why the object made by Makerbot is so small.

    Wayne

  5. #5
    Pixel Flipper kvanover's Avatar
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    Quote Originally Posted by MicroMouse View Post
    The internal unit of measurement for a LWO file is the meter.

    When LightWave displays the units in inches on the screen that is for the convenience of the user only. When you make a one inch cube it is converted to its metric equivalent which is 0.0254 meters.

    When you export to STL or OBJ file your one inch cube is written as 0.0254 meters and that is why the object made by Makerbot is so small.

    Wayne
    Thank you Wayne.

    I just ran a test print of a 1 Meter cube and it measures 1 inch when printed.

    I'm not going to pretend that I fully understand why this is working, but as for now this gets me printing some of the parts I've been trying to get perfect for a few days.

    Thanks mates!

  6. #6
    Man of many cells. shrox's Avatar
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    Try 3937, or 39.37, there is a correlation between the number of inches in a meter and stl files.
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  7. #7
    Pixel Flipper kvanover's Avatar
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    Quote Originally Posted by shrox View Post
    Try 3937, or 39.37, there is a correlation between the number of inches in a meter and stl files.
    Do you mean scaling up in Replicatorg by 3937 or 39.37?

  8. #8
    Man of many cells. shrox's Avatar
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    Quote Originally Posted by kvanover View Post
    Do you mean scaling up in Replicatorg by 3937 or 39.37?
    Yes, I could be wrong though...
    shrox www.shrox.com
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  9. #9
    Pixel Flipper kvanover's Avatar
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    Quote Originally Posted by shrox View Post
    Yes, I could be wrong though...
    Still didn't work, it did however have the same effect as hitting the mm > inches button.

    I'll keep the numbers in mind if I see them come up.

    Thanks!

  10. #10
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    You're welcome, kvanover,

    You can build your model in inches as you were originally doing.

    As I said earlier, one inch gets converted by LightWave to its metric equivalent which is 0.0254 meters.

    The Makerbot software assumes that the unit of measurement in an OBJ or STL file is the inch.

    When your model is exported to either the OBJ or STL file, the vertex coordinates have to be scaled by a factor of 39.37 because there are 39.37 inches per meter.

    Example:
    0.0254 meters multiplied by 39.37 inches per meter equals 0.999998 inches or 1.0 inches when rounded.

    Wayne

  11. #11
    Not sure if you have figured this out yet or have come up with some other solutions.... I would love to hear them as this is a pain!

    here's my workflow

    Complete model using LW's internal scale

    save LW version of model before OBJ export

    SHIFT "h" (size) then n (numeric)

    scale model by 100000

    export OBJ

    import into meshlab

    convert to STL

    upload to http://cloud.netfabb.com/ to fix any errors and make sure the mesh is water tight

    PRINT

  12. #12
    Paintball Video Geek billmi's Avatar
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    My workflow is quite similar.

    Model in LW, scaled to the dimensions I'm after - it doesn't matter if I set modeler to metric or inch display, since internally it's basing things on the meter.
    Increase size of the model (with Shift h and Numeric) by 100000%
    Export from LW using the SHM STL Exporter plugin.

    From there it's straight into Slic3R to generate the G-Code toolpaths and then Pronterface to print on my Prusa Mendel.
    Toasting with NewTek since 1991 - Corinthian Media Services
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