zhou436
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Posts posted by zhou436
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On 2/13/2020 at 1:52 PM, geert_2 said:
Also, when calculating the STL-triangles in MATLAB, make sure the coordinates of begin- and end-points of shared triangle-vectors are exactly the same, down to the last digit behind the decimal point. If these X-, Y- and Z-coordinates would be rounded off in your calculations, even to 20 digits behind the decimal point, it might create gaps in the STL-file, and then it would no longer be watertight.
Let's say you have 3 triangles A, B, and C that share one corner. If this corner is (x, y, z): for triangle A=(10.00001, 20.00001, 30.00001), and for B=(10.00002, 20.00002, 30.00002), and for C=(9.99999, 19.99999, 29.99999), then this model would not be watertight, and would get messed up in slicers and CAD-editors, even though the gap of 0.00001 is not visible on-screen.
(I think this is the problem that SketchUp has with 3D-printing too: it was originally designed for visual models only, like in computer games, but not for watertight printable models. Models look solid on-screen, but when you zoom in 10000x, you start seeing gaps.)
Maybe you can add calculations to make sure that points that are very close together, do snap onto each other? Similar to the "snap" function in Powerpoint, Inkscape, and most 3D-CAD programs. Make this snap-radius adjustable, e.g.: "if points are less than 0.001mm apart, then snap them onto each other", but then in a math formula. So the three shared corner of triangles A, B and C in the example above, should all snap to (10.000, 20.000, 30.000).
Thank you very much!
It was my stl file problem. The normals of inside bubbles are random, but not point to inside. I wrote a script to check this kind of thing and it is solved.
Thank you for your advices.
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On 2/12/2020 at 10:53 PM, gr5 said:
I got it to work by unchecking "union overlapping volumes". Works perfectly. Yes - the normals are random. The STL file as an unordered list of traingles and there's no way to know which triangles are connected to which other ones other than they should have shared vertexes. Anyway each triangle has a normal which says which side of the triangle is "air" and which side is "solid". those seem to be random in you model. MATLAB isn't setting those. I could be wrong - matlab may be doing it right. I'm not certain but that is my guess as I don't normally have to mess around with the "mesh fixes".
Anyway, just uncheck "union overlapping volumes" in mesh fixes (I might have changed other mesh fixes so here they all are):
Thank you very much!
It was my stl file problem. The normals of inside bubbles are random but not point to inside.
Thank you for your advices.
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2 hours ago, geert_2 said:
As far as I know, STL-files have no dimension units (mm, inch, meters,...). But if I remember well from older posts, Cura *assumes* that the dimensions are in mm? Is that correct? If so, maybe you can set that in MATLAB to render or export the model to a size of maybe 20...50mm? And then definitely run it through an STL-analysis and repair, just to be sure.
I think I did not set units in MATLAB (actually I do not know how to do it). I set a unit 1 for the cube. I think we can modify the unit inside Cura.
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35 minutes ago, eldrick said:
All the external surfaces are inside-out, i.e. not normalized. Run it through https://service.netfabb.com/login.php and it might be able to correct the errors.
Thank you very much for your suggestion and website. It works, however, deletes all my precious-voids.
I will try to solve the output problem in MATLAB tomorrow morning and see what happens.
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11 minutes ago, geert_2 said:
My old Cura version can display this model, although it appears extremely small, maybe 1mm^3. So I have to scale it up 20...50x to make it printable. However, this older Cura-version can not slice it: then it hangs up. Maybe there is something wrong with the STL-file?
Maybe try saving it with different parameters? Or run it through an STL-analysis and repair program? But I have no experience with these, as I never needed them for myself.
Thank you for your reply!
I outputed it with MATLAB by myself, therefore, it could happen that there are many problems with the surface norm or other things. I will check my code, if something nice happens, I will let you know.
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12 hours ago, gr5 said:
I don't see any problems - I don't see any horizontal surfaces. In the screen shot I see black holes where you want holes. Right? That's good, right? No horizontal walls. No walls of anykind except on the outside of the cube. Please zoom in some more. Please move the layer up and down a bit so that none of the part is colored gray.
Use scroll wheel to zoom.
Use right mouse to orbit. When you do this I think you will see better in 3 dimensions that the part is exactly what you want. Or maybe not?
Use shift+right mouse to pan.
Please zoom into the area you think is a problem and maybe you can add an arrow pointing to this "horizontal surface" that I don't see.
Note that there are many features under "mesh fixes" plus there is a plugin that I strongly recommend. Sometimes these fill in holes that you don't want filled in but it looks to me that it is printing it perfectly?
infill
Could you explain why you want voids *inside* the part? Will anyone be able to see these? Are you planning to use transparent filament? I don't understand about these voids if they are invisible then what is their function?
I can send you the stl file. I wish you could take a look when you are free. I think you can easily understand the problem when you load it in your ultimaker cura. Thank you.
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12 hours ago, gr5 said:
I don't see any problems - I don't see any horizontal surfaces. In the screen shot I see black holes where you want holes. Right? That's good, right? No horizontal walls. No walls of anykind except on the outside of the cube. Please zoom in some more. Please move the layer up and down a bit so that none of the part is colored gray.
Use scroll wheel to zoom.
Use right mouse to orbit. When you do this I think you will see better in 3 dimensions that the part is exactly what you want. Or maybe not?
Use shift+right mouse to pan.
Please zoom into the area you think is a problem and maybe you can add an arrow pointing to this "horizontal surface" that I don't see.
Note that there are many features under "mesh fixes" plus there is a plugin that I strongly recommend. Sometimes these fill in holes that you don't want filled in but it looks to me that it is printing it perfectly?
infill
Could you explain why you want voids *inside* the part? Will anyone be able to see these? Are you planning to use transparent filament? I don't understand about these voids if they are invisible then what is their function?
Yes, you are right. From the x-ray view, we can find no problem. However, I think from the layer view, you could see the differences. The holes or called voids can not be printed properly, as they divided the voids into several slices and between the slices there are walls to divide them.
The reason I want to print it in this way is that I want to print foam like structure according to my mathematical models for experiments not for fun. Therefore, it is not that important they are visible or not.
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3 minutes ago, gr5 said:
Please include a screen capture of what you are referring to.
I'm not sure if these are vertical, horizontal or tilted holes. I'm not sure what you mean by walls (straight, curved)?
Please include a screen shot in "PREVIEW" mode (near top of cura) and set "color scheme" just below that to "line type".
At first, thank you for your reply!
I attached 2 screen shots. On the left side is the layer view. You can not see the bottom of the left huge bubble. However, from the right graph you can see the shape of the bubble, which does not include a horizontal surface.
Therefore, I think it divide my bubble into different slices and create horizontal walls between.
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Hi,
I want to print a 3D model full of holes inside. However, when I check my model in Ultimaker Cura, it discrete the holes into several slices and create horizontal walls between them. I am sure, that I did not create walls by myself when I create the model. The x-ray does not show the walls anyway.
I think they are some kind of support, however, when I check the support in the software, it is not crossed. Do you have any idea how can I avoid them?
Question on printting holes inside the model
in UltiMaker Cura
Posted
Thank you for all the replies!
It was my stl file problem. The normals of inside bubbles are random, but not point to inside. I wrote a script to check this kind of thing and it is solved.
Thank you for your advices.