Non air-tight (and flawed) design sliced with large aeras closed

[johnroy22222 0]

Hi,

 

I ve been trying to re-use a perfect design of an air-vent from here : https://www.thingiverse.com/thing:3195581

 

This original design has no issue at all.

 

Being fully aware that in the end i ll have to restart from scratch my design , I can't figure out why my modifed version of the air-vent has its geometry closed... (the top of the air vent should be opened, there are 3 openings, the sliced result, and the PLA printed part, has its top surface fully closed, no air can go through !)

 

I ve played a bit with the exciting new "Mesh fixes" parameters of Cura 4.7.1 , (which could save a lot of time in flawed design...amazing new features !) but with no success. The sliced air vent output is still closed.

 

I tried meshmixer in an attempt to first "automatically fix the design" (it requires some talent with the various settings...) with no success and secondly to "drill" the closed openings. But no result either.

 

I m aware i ll have to redesign from scratch (the thread is a complex part for me, re-use is still a welcome solution), but if anyone has any hint of how else I could address this...

 

Clearly my design is the issue. But why is Cura closing such big openings ? Is there some ground rules which I failed to follow ? Is there some workaround in Cura ?

 

Thanks in advance

 

JR

 

 

 

 

air_vent.3mf

[Framar 38]

Your model is probably wrong. I can try fixing the model using the STL but would be easier sith a STEP file.

Can you post your CAD file?

[tinkergnome 926]

On 11/10/2020 at 2:56 PM, johnroy22222 said:

Is there some ground rules which I failed to follow ?

 

Basically - make it manifold. It has to be a solid single object and watertight.

- no "floating" faces

- no overlapping faces

- no internal geometry

- no holes in the mesh

 

This model has all of it🙂 as far as i can see...

Whatever you did - it does not work this way.

There are step-files in the original design. I recommend to use these as the basis and make your modifications with a proper CAD program. FreeCAD could be used, or even Fusion360 if you want.

 

Some pictures:

 

The X-Ray-view in Cura gives a rough indication of all "problem zones" (marked in red).

 

 

3DBuilder imports it like this:

 

 

 

Meshmixer counts 88 separate shells that are not connected to each other

...and PrusaSlicer counts the errors in more detail for you:

 

[geert_2 557]

In addition to what thinkergnome said: do *not* design it in SketchUp, as this creates exactly the problems you have now. And probably also not in Blender, as this also occasionally seems to cause problems, but less than SketchUp, and it is way more powerfull (also way more complex).

 

Another program you could use is DesignSpark Mechanical (freeware, requires registration). I never had any such problems in many hundreds of designs.

 

If you have to redesign from scratch anyway, see if you can replace the thread with a plain hole, and a bolt and nut, or similar standard hardware. That would make printing easier, and cause less post-processing afterwards. (I don't know what has to go in there, so hard to say what the options are.)