STL Export Problems with Alignment for 3D Printing

[Anonymous]

I am exporting STL files to be used with a 3D printer. There are two solids, which are exported separately and then imported into the slicer software. However, the origins are off when they are loaded into the slicer - this is an AutoCAD problem, as this problem persists across several slicer programs. The objects are aligned when exporting, but misaligned when loaded into the slicer. I found this same problem in the Fusion 360 board, but the same fix doesn't apply to AutoCAD 2014. (If this problem is fixed in the latest release we will be upgrading next week) https://forums.autodesk.com/t5/design-and-documentation/exporting-separate-stl-files-in-the-correct-... Any ideas?

[JDMather]

Attach example dwg and zip and attach resultant *.stl file(s) here.

Where is your origin in dwg file?  (that is the first thing I will be checking when you attach your file here)

[Anonymous]

Thank you for the quick response!

Zipped files are attached as requested.

[Anonymous]

Here's the DWG file. Thanks

[JDMather]

I found a lot of things I don't understand.

1. There are 4 solid bodies in the dwg file (2 of which appear to be dupicates.

2. The largest part is 10 inches long - longer than most 3D print envelopes.

3. The parts appear to be modeled perfectly, that is, no clearance between parts.  In the real world perfect parts cannot be manufactured and 3D printing requires more clearance than machining processes.

4. I didn't see anything "wrong" with the stl files.  We move our geometry in the slicer.  It is not clear to me what you are trying to do.

[Anonymous]

I forgot to union the 3 support pieces together in the DWG. The piece is 10mm, not inches. I checked 'units' and it is set to inches, but it never seemed to matter to the slicers, they all took it as mm. Cura and MatterControl both pull the STLs in out of alignment. I'll play with tolerances and things once I can get two pieces exported out of AutoCAD to match back up in the right spot in the slicer. I got it to print properly by moving the support out of whack in AutoCAD until it lined up properly in the slicers, and it printed without issue. What slicer do you use? Cura doesn't let you move the objects independantly. MatterControl does, but it isn't perfect as it doesn't have snaps. I don't think it's crazy to expect two objects exported from the same file to wind up in the same spot when imported.

[JDMather · Accepted solution]

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@Anonymous wrote:
... I don't think it's crazy to expect two objects exported from the same file to wind up in the same spot when imported.

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Your parts are not modeled entirely in the positive x,y,z octant.

I think that if you move the in to the positive octant before exporting to stl - your problem will disappear.

Your parts have negative x coordinates.

AutoCAD moved the most negative x coordinate to zero.

There was a time when AutoCAD would not allow you to save a part with negative coordinates to stl.

[Anonymous]

Yep, I completely overlooked that part. Thank you for your help!

[Anonymous]

Confirmed, that was the problem!