Problem STL file 20x larger


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    Default STL file 20x larger

    I have a STL file from another cad system importing 20 times the actual size. I tried units, from English to metric and that's even worse.
    This is the second time from this person. I had to request dwg from him to get a working model.
    Ideas?

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    Default Re: STL file 20x larger

    Some cad programs have issues importing and exporting various file types. Ask the individual who made the original file what drawing units he was using... inches, mm, etc. I know I said you checked, but sounds like the original was drawn in MM and you are importing it as inches. 1in=25.4mm Depending on what his software is set to and what you are importing it as it could easily be 20x off.



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    Quote Originally Posted by artracing View Post
    I have a STL file from another cad system importing 20 times the actual size. I tried units, from English to metric and that's even worse.
    This is the second time from this person. I had to request dwg from him to get a working model.
    Ideas?
    Stl file have no "unit format" information. Just "1 unit = 1 unit"....

    So while you can fool around with "set your system to mm, then merge the file, then change units to inches" etc, this can still produce erroneous results.... sometimes the scale needs to be the answer. So open model and select translate, then tick the scale option and try the various conversion numbers till the model is the size you expect. So like .03937 etc...



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    Default Re: STL file 20x larger

    Quote Originally Posted by BurrMan View Post
    Stl file have no "unit format" information. Just "1 unit = 1 unit"....

    So while you can fool around with "set your system to mm, then merge the file, then change units to inches" etc, this can still produce erroneous results.... sometimes the scale needs to be the answer. So open model and select translate, then tick the scale option and try the various conversion numbers till the model is the size you expect. So like .03937 etc...
    I had them send me DWG and its the same way.

    Rob



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    Quote Originally Posted by artracing View Post
    I had them send me DWG and its the same way.

    Rob
    The DWG can contain just the same, poly data. Not transformed. Just scale it.



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    Default Re: STL file 20x larger

    Quote Originally Posted by BurrMan View Post
    The DWG can contain just the same, poly data. Not transformed. Just scale it.
    So to scale a part I go to preferences, units, and use custom, 1 unit = xxxx mm

    Rob



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    Default Re: STL file 20x larger

    If it's a mm/inch problem try setting all your defaults to mm and saving the file before you import the part.

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    Default Re: STL file 20x larger

    Quote Originally Posted by artracing View Post
    So to scale a part I go to preferences, units, and use custom, 1 unit = xxxx mm

    Rob
    No, start the translate command and tick the scale option and enter the .03937 there...Select your part. Select OK.



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    Default Re: STL file 20x larger

    Quote Originally Posted by magicniner View Post
    If it's a mm/inch problem try setting all your defaults to mm and saving the file before you import the part.
    That's another way... Would just need to figure if mm, cm, etc from the originating app... But you may find that this type of conversion is a bit more difficult and doesn't always work out, when you start CAM'ing the part....



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    Default Re: STL file 20x larger

    Quote Originally Posted by BurrMan View Post
    No, start the translate command and tick the scale option and enter the .03937 there...Select your part. Select OK.
    Thanks again. That worked. If he did the drawing in metric, why wouldn't just selecting metric units in preferences work. Is it because its not bobcad file or drawn in another program?



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    Default Re: STL file 20x larger

    Quote Originally Posted by artracing View Post
    Thanks again. That worked. If he did the drawing in metric, why wouldn't just selecting metric units in preferences work. Is it because its not bobcad file or drawn in another program?
    It's because your defaults aren't metric so you import a part that is sized in "Units" (the file doesn't carry a definition of a measurement system between different software packages) into a system that thinks "1" is 1 inch, changing the units simply converts that to mm, it doesn't change the size.

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    Quote Originally Posted by magicniner View Post
    it doesn't change the size.
    Some packages DO scale the parts with the unit conversion!

    This is a repetative mistake made, where people just think "flipping the units is no big deal" "just go ahead and dont worry about it"....

    No..... "think about it and understand what your software is doing" is much better advice...



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