CURA closes my tubes [SOLVED]

[assafp 1]

Hi!

  I've looked at every forum thread I could and made all the recommended changes and still the problem persists. Thanks in advance for the help, I'm 1 week into 3d printing.

 

Printer: Creality 3 Pro

Design Software: Blender

Slicer: Ultimaker Cura 4.7.1

Problem: a hollow tube (or any designed hole) in my model is automatically filled up by the printer.

 

Things I've tried:

  Unchecked "Remove all holes"

  Used Mesh Tools to "Fix simple holes" -> "Mesh needs more extensive repair to become watertight."

 

Attached a simple stl of a tube - The tube is correctly printed hollow but the printer incorrectly seals the tube from the top and bottom for some unknown reason.

rod test.stl

 

 

Edit: This problem was SOLVED - simply use Extrude or other tools inside Blender to thicken your walls, thus allowing the printer to print a model with real-world thickness, as opposed to the infinitely thin walls of Blender's default virtual world.

Edited November 17, 2020 by assafp

[geert_2 556]

Tiny holes (e.g. <1mm) tend to get filled up because the molten filament is pulled inwards into the curve, like when you try to pull a rubber band into a circle.

 

But most likely your model is defective, and has unwanted surfaces on top and bottom? So you might need to correct that in Blender, or run the STL through a repair-program. But I have no experience with this, so I can't give recommendations. When designing in DesignSpark Mechanical, I never had such problems, it always produced good STL files.

[tinkergnome 924]

6 hours ago, assafp said:

I've looked at every forum thread I could and made all the recommended changes and still the problem persists. Thanks in advance for the help, I'm 1 week into 3d printing.

 

 

This are only faces with zero volume.

The crux is: a non-manifold geometry can not be printed. Most slicers try it anyways, but the result is usually not what you expect. Some hints:

https://www.sculpteo.com/en/3d-learning-hub/create-3d-file/fix-non-manifold-geometry/

 

Designing for "real world things" is very different from the "just for visualization" - approach.

If you design functional parts a good CAD program would be the better choice (as @geert_2 said).

 

For this simple example you can either:

- in Blender: close the top and the bottom with faces and in Cura: set top and bottom thickness to zero and choose a reasonable wall thickness

or

- use the "Solidify" modifier in Blender and define the thickness of the outer wall this way

 

 

 

There's a builtin add-on in Blender called "3D Print Toolbox". It can check models for several error types.

 

 

[assafp 1]

Thanks @Tinkergnome, still doesn't work.

Quote

in Blender: close the top and the bottom with faces and in Cura: set top and bottom thickness to zero and choose a reasonable wall thickness

 This won't work because I have models whose hole openings are not the top or bottom layers of the model. 

 

Quote

use the "Solidify" modifier in Blender and define the thickness of the outer wall this way

Tried this and imported the resulting stl to Cura. Result was an errorless model (no red marks in x-ray mode) BUT when sliced, the print job is said to take 0 minutes (which in fact resulted in the printer printing nothing).

 

Any other ideas?

[gr5 2,005]

That's almost surely because the wall is too thin.  If your line width (typically equal to nozzle width) is 0.4mm then the minimum wall width is 0.8mm by default.  Cura will do thinner walls if you check the box "print thin walls".  down to something like maybe 0.4mm.  You can set your nozzle width to 0.1mm just as test to verify that your walls are too thin.

 

If you are printing a hollow cylinder and only want to do one pass on the walls, I would model it as a solid cylinder in CAD and print with no infill, no top and no bottom.  That way you can get extra thin walls.  This only works for vase/cup/cylinder types of prints.  If you have something more complicated (99.99% of models) then this won't help.

[assafp 1]

@gr5, you're a genius!! "Print thin walls" caused a backfire where the printer jumbled all the strands. But thickening the walls on Blender using modifier "Solidify" (thanks @tinkergnome) worked. Thanks!!!

[assafp 1]

Uh oh. I celebrated a bit too soon. The solution above worked for a simple tube; However, a slightly more complex model (a tube within a tube) did not undergo the "Solidify" modifier well - it deformed the model completely.

 

Any other advice?

CE3PRO_toaleta clean rod 2.gcode toaleta clean rod 2.stl

[tinkergnome 924]

7 hours ago, assafp said:

Any other advice?

 

Did you read the article about "manifold geometry"?

You have to model an object that can exist in the physical world. Walls without thickness do not exists and are not magically generated. You have to model them.

It doesn't matter how you do this. Extrude the faces, use insets, close the geometry - whatever works for the given task. 🤷‍♂️

The solidify modifier can't repair a broken topology.

 

It's possible with Blender - there are lots of tutorials on youtube about proper hard surface modeling for 3D printing, the importance of good mesh topology and so on. If you have fun with it - do it,  stick with it.

 

An example:

https://www.sculpteo.com/en/tutorial/prepare-your-model-3d-printing-blender/modeling-3d-printing-blender/

 

But Blender is for sure not the best tool for this task and you will have a hard time in the beginning.

You can have a much easier start with 3D printing if you use a 3D-CAD program instead. There are even free ones.

A lot is possible - and you have choices... i'm just saying..🙂

 

[assafp 1]

Well @tinkergnome has SOLVED it. Instead of repairing the stl using some external software (which 99% fails), I merely thickened the walls in Blender using methods like Extrude.

 

Side note: I looooove Blender and prefer it to other alternatives so THANK YOU for helping me figure it out!

Edited November 17, 2020 by assafp