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hbass1-Visitor
1-Visitor
April 22, 2016
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Issue: STL parts in an assembly separate when 3D printed

  • April 22, 2016
  • 1 reply
  • 3246 views

I have made several models in Creo supporting our FIRST Robotics team.  I've noticed on many occasions, that when I print these (Fusion F306 printer or others), the models often separate along the intersection boundaries of where one part has been placed inside another for the combined Assembly.  For example, in the Panda bear screenshot below, the legs will print as posed, but separate easily along their original part lines when the model is handled.  I believe the cause is that the triangles defining each part don't merge into one another for a true solid model assembly.

For a better assembly, I would love to apply a fillet or other material, or perform some operation that "merges" or stitches these parts into 1 solid mass. We are certainly getting good parts, using the "solidify" command during creation, and passing the model inspection tools.  When I print parts alone (not assemblies), they come out just fine, even when they involve several intersected primitives, such as the panda_head in my model below. Typical chord length for STL generation has been 0.01 to 0.001", with 0.5 step angle. We use Solidify 3 for our slicing/g-code generation.

I welcome your input, and have provided my Creo parts for sharing, criticism and analysis.

PandaSittingScreenCapture.JPG


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Best answer by TrainStopper

May not help, but what I do to turn assemblies into parts is to export as IGS, then open the IGS as a PRT and make your STL from there.

That might be able to determine whether the issue is related to making STL models from ASM vs PRT models.

Beyond that, I have found crazy glue type adhesives work really well, apply some before the part breaks and it might not break at all.

For my 3D printing, I set chord height to 0 so it makes it the minimum, then I set angle control to 1 for the finest resolution.

Good luck!

1 reply

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TrainStopper12-AmethystAnswer
12-Amethyst
April 29, 2016

May not help, but what I do to turn assemblies into parts is to export as IGS, then open the IGS as a PRT and make your STL from there.

That might be able to determine whether the issue is related to making STL models from ASM vs PRT models.

Beyond that, I have found crazy glue type adhesives work really well, apply some before the part breaks and it might not break at all.

For my 3D printing, I set chord height to 0 so it makes it the minimum, then I set angle control to 1 for the finest resolution.

Good luck!

    H
    hbass1-VisitorAuthor
    1-Visitor
    May 11, 2016

    The export and import via IGES did the trick!

    I've been using the crazy glue solution, and that works, as long as the model stays together during the 3D print process: sometimes the interfaces are so loose, it falls apart on the print bed.

    For those who come across this article in the future, I used Save As IGS file type, then selected Solids (as opposed to surface) export type. Nothing special needed on the import, and when saving as STL for the 3D print, I didn't have to go as small as TrainStopper suggested: the 0 chord height actually gets changed automatically by Creo to 0.0002" (using inch-pounds-seconds units, that's 2 ten-thousandths of an inch over a 3 inch model) which produced a 25MB file.  I used 0.001" chord height, and got about a 3MB file, with abundant triangles to keep a very smooth surface finish.

    Thanks for the trick!!

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