Printing a tube (or how to not close hollow objects)

I'm relatively new to 3D printing. I purchased a Robo3D three months ago, and 3 weeks later returned it and bought a Makergear M2; much happier now. I've been using Slic3r mainly, but have also played around with Cura. But now I'm having an issue with a part I designed and I can't seem to figure it out.

My part includes a tube that will be connected to rubber tubing on one end and left open on the other (an outlet). I created the attached test file to demonstrate the problem. This file is a small right-angle piece of the tube that is hollow inside and should be open at either end so water can flow in and out. However, when I print it I always end up with an enclosed object. To complicate matters, though I can easily make this test part hollow by setting infill to 0%, I will need infill for the rest of the model when I print the full part, so I also need to find a way to print this tube hollow without turning off infill. But I guess one problem at a time.

So far I have tried:

• Turning infill density to 0%
• Checking off "only infill where needed"
• Using Cura (which introduced a whole host of other problems)

I'd appreciate any suggestions.

Thanks,
Nicholas

Hi Nicholas,

I think there's something screwy with your .stl file. What software did you ise to produce it? When I load it into Cura, I don't see any sidewalls between layer 34 and 92 (layer height = 0.1mm). If I rotate it through 90 degrees, there's still a section where the wall is missing.

I suspect that the walls are zero thickness? i.e. it's a solid object rather than a tube.

Frank

Hi Frank,

That's possible. I've worked with 3D programs like Bryce and Vue for a couple decades, but I'm very new to modeling 3D objects myself. I used FreeCAD to create this file, as it was the only software I could find within my budget . When I look at it in FreeCAD I can see right through the tube so I assumed it was hollow, but the walls do look zero thickness and I wondered about that.

Would the solution be to learn how to modify the object in FreeCAD to have walls of non-zero thickness and then try exporting as STL again?

Thanks,
Nicholas

Yes, you'll need to build it properly in FreeCAD.

I'm not sure how I'd make your object... maybe start with a sketch of two concentric circles. Pad that to make a tube. Revolve it through 90 degrees to make the corner.

Also look at [www.thingiverse.com] to give you some ideas.