Autodesk Inventor

[#1]

Howdy fellas. I'm designing a flashhider that fits on an airsoft gun using AutoCad Inventor and trying to print it using the 3D printing service, Shapeways. The threads on the gun are M14-1 and when I use the thread feature in Inventor all it puts on the part is a 2D texture. When I upload the model to any other software (Meshlab for example) the threads are gone. So, I downloaded a pllugin that models the threads in 3D. This fixed the problem in part, but when I upload the model to shapeways (in an .stl format) I get some weirdness.

Here's the flash hider:

And here's what shapeways thinks I upload:

It somehow fills in the hole that I tapped and threaded. Is there any way to fix this?

[#2 · Accepted solution]

If you increase the quality of the stl file during export does it fix the problem?  When you do a save copy as to save to stl hit the options button before you save and mess with those settings..

[#3]

You know what, that totally fixed the problem! (I also drew the thread manually)

[#4]

Also check the units when creating the stl as Inventor defaults to CM rather than document units.