Problems with STL files from Autodesk Inventor?

(I apologize in advance for cross-posting, but on the off chance that this is a hardware problem rather than a software problem, I thought I had better check here as well.)

Howdy. New user (Taz 5, 0.5mm nozzle, running tethered using supplied version of Cura).

I’ve gotten over the pains of making sure the Z leadscrews are level, leveling the bed, waiting a week for a replacement for the cracked idler bracket (don’t ask), but now I’m a bit stymied.

I have printed my Bed Calibration file, my Rocktopus, and 3x replacement idler brackets (not getting shut down by THAT again), BUT- I cannot seem to succeed at my first ORIGINAL print.

(Screen capture from Inventor)

I created the part using the full (paid for) Autodesk Inventor Professional (2014), and exported from Inventor to an STL file. There are no discontinuities in the part file (tried to keep it simple, see attached STL file, don’t ask my why I used 2016 instead of 2015…). Cura appeared to import the file properly. Scrolling around it looked fine. Scale: 3/16" at its thickest, 4.25" long.

I’ve now attempted to print this file twice in PLA on the “High detail” mode using the “PLA (eSUN)” presets at 220 degrees extruder/60 degrees bed. In each instance, the print failed at, from what I can tell with my calipers, exactly the same point- the transition from flat base to border/lettering. The extruder kept moving in each case (on each part, you can even see where the extruder either scraped or heated the part as it carried on making the shapes to create the letters), but the feed of plastic into the extruder stopped.

I am trying to figure out if I have somehow exceeded the capacity of the printer (unlikely- none of the letters are less than 1mm thick) or if there is something in the STL conversion process from Inventor, or… ? Wit’s end, any help appreciated.


CHRISTMAS2016.stl (660 KB)

The file is fine. Inventor will occasionally generate a non manifold STL on particularily complicated parts (especially round ones for some reason) but this one is intact. There are no internal structural wierdness issues, it’s manifold, it should print fine. The letters might be a little thin in places. What is probably going on is you are overextruding a bit. Depending on the infil level, if you are at or close to 100%, on the last couple layers when it does a 100% solid surface pass, if you are overextruding and if your idler arm springs aren’t set right, that can cause backpressure on the molten plastic trying to exit, which in turn is basically the equivelent of trying to extrude plastic through a solid brick wall. The molten plastic stops, which in turn backs up the unmelted plastic, but the hobbed bolt keeps turning, and suddenly you have a C shaped chunk missing from your filliament and nothing comes out.

First off, check your filliament diameter and see if it matches what you have set in Cura. The default is either 3.00mm or 2.85mm, and most of the filliaments out there will range in size from 2.79mm to 3.12mm in width. if you have a smaller setting and are actually extruding a larger filliament, your calculations are off.

Also make sure the distance between the washers outside the springs on the idler arm tension bolts is 8mm. PLA might want it a little looser than that, but it’s a good place to start. If they are too loose, the hobbed bolt doesn’t cut deep enough into the filliament, and only exerts force on the outer edge, which isn’t as strong as it would be if it was cut more deeply into the side. that grinds away, then it continues sawing in until it can’t reach anymore plastic.

I downloaded and took into Simplify 3D and it processed and appeared to be fine in the simulated printing. S3D will not do a defective file. I suggest perhaps your slicer program is causing a issue.