How do you find out the volume inside an STL?

A Beaker is useful for determining volume

A Beaker is useful for determining volume

A few days ago I started designing a new case for my new Polargraph drawing robot brain.   ((Joe Penniston via Compfight))  My goal was to design a simple to design, simple to assemble, and sturdy box-like case.  ((One of the reasons I am interested in a box-like case is to make sure it is easy to mount on a wall or inside a larger project box.))  However, I was stumped when it came to figuring out whether my new design conserved plastic better than the other Polargraph case design from Sandy Noble on Thingiverse.  After experimenting a little, these are the two easiest ways I found to figure out the volume within an STL file.  ((While particularly simple, I suppose if you had a really large beaker and a certain volume of water, you could print your STL file, submerge it, and compare the results.  However, this seems impractical for a lot of reasons.))

  1. AdMesh
    1. Tony Buser was kind enough to suggest an application I had never heard of before – AdMesh.  AdMesh is a free command-line tool created by AMartin1 which can provide all kinds of information about an STL file.  After fiddling around with the program a little bit, I found this command gave me the best results:
      • admesh –normal-directions –tolerance=0.01 –exact %1 >> stl-stats.txt
    2. While AdMesh worked pretty well overall, it had problems with some STL files and was unable to provide statistics.
  2. NetFabb
    1. Alternatively, NetFabb also provides some ways to find out the volume inside an STL file.
      The little button circled in red

      The little button circled in red

      1. NetFabb’s cloud-based STL repair service provides information about the repaired file including surface area, triangles, and volume.  Just submit your STL file for repair (even if it doesn’t really need it) and get back a link to your fixed file along with the relevant statistics.
      2. NetFabb’s “NetFabb Studio Basic” is a free downloadwhich also provides detailed statistics about STL files and basic mesh fixing tools.  Here’s how you do it:
        1. After you open NetFabb, “Control-O” will give you the option of selecting an STL file.
        2. Keep adding as many STL files as you would like.  It won’t matter that they are all overlapped.
        3. Click the third icon from the left, a little cube frame with a circled “i” on it.
        4. A window will pop up providing information, including volume, for each of the STL’s you have imported.
      3. I found the Studio Basic version of NetFabb’s offerings to be more useful.  The statistics seemed to be more consistent than the values from the cloud service and Studio Basic also allows you to import numerous files at once so you can compare the numbers “side by side.”

Do you have a suggestion on how better to figure out the volume in an STL?  If so, let us know in the comments!

  1. Sorry!  I couldn’t find your full name! []