I've been trying to print a file from a brain gear from Thingiverse, but the gear needs to be rotated to sit on one end. I'm doing that in Sketchup. I've installed the .stl import and export extension, and I can get the gear into Sketchup and rotate it. The gear has holes around its middle in addition to the big hole thru. One curious thing: the gear comes into Sketchup below the Z=0 plane, though if I directly import it into Slic3r, it's above the Z=0 plane. A picture of the gear is attached.
When I try to export from Sketchup and use the .stl export feature, I get a gear that isn't correct when I import into Slic3r and look at the view/cut window. The holes around the middle are filled in. However, if I export an .obj file from Sketchup and import the file into Slic3r and look at it in the view/cut window, it looks perfect. When I export in .obj, I have to select the "export two sided faces" option to get the holes to appear correctly.
Then, if I slice the gear from the .obj file, I get an extremely tiny file (tens of kBytes) that only prints one layer. I don't get the whole gear.
The .stl files with the filled in holes appear to slice and create printable files.
How do I get the whole gear with the holes just like in the view/cut window?