#105 | 3dp00 – Exporting STL to Gcode & fixing non-manifolds model

Hi guys!

Today I’ll talk about 3d printing since I am struggling with my model. You certainly already know my project about making a dome on Mars, so I won’t give you too many details about that. This time, I was trying to print the model in 3D since it is a while I don’t even touch to my self-made printer (last time was for the making of the protective box-shell for the Arduino of our drone (#03 and #04)). I was used to work with a software called Slic3r for the “slice” layers of a 3D model but the software crashes a lot for big size data model.

I used to export the 3d in .obj into the slic3r where I can generate some support for the hangout part of the model. However, the 3D parts of my dome have a lot of vertices and meshes, that can’t be simplified. So, Slic3r can’t import all the file. I solve the issue by splitting apart the 3D model into the extern shell and the trees/slab.


The dome was the first step for the printing since the thickness of the material is bigger than the trees. I needed to print the dome on the heatbed, so I also need to scale the object at something printable: I chose to print it on a scale of 1cm = 10m. My heatbed is approximatively 20cm x 20cm x 20cm and my model, 16cm diameter, so it should be fine at this size.
First, I tried to import in .obj into the Slic3r, but the file was too big even if I sliced the model in two. Plus, there were a lot of issues concerning missing meshes and vertices. So, what I have done was to change the importing extension of the file in “binary .stl” and only with geometry (no texture). That way, I managed to make a simplified… Wibbley wobley timey stuff… Without unnecessary details.

fig.01 – I have changed some parameters for the support of the dome (like the layers, and the infill of the 3D print). It took me 3 hours of struggling to get a right model without geometry failures. The 3D printing part needed 14 hours and 16 minutes to finish but hopefully, the printer succeeded for the first try. 












Slab and trees

I am still working on this part since the model is at a really small ratio scale compared to the real deal, the trees will be a lot smaller than the reality. So, the layers on the structural part of the trees will be really thin and I don’t know if it will be able to print it correctly. Slic3r is good to visualize what you have to do and quickly, however for precise slices less than 2mm, I needed another software. I search a bit and I tried different free software: Meshmixer is really interesting for “tree supports” for my trees (no joke). The tree supports use fewer materials to support a hangover part of an object, but only if the surface is not parallel to the ground. You can read a good article here at prusaprinter. It is also really interesting to use the Meshmixer to check the issues of geometry in your model. In my case, it was a really big issue for non-manifold surfaces: overlapping faces. The software was able to analyze the issues and fixed it automatically without changing the general shape of your object.

fig.02 – Meshmixer can be quite really useful for “tree supports”
fig.03 – The Ultimaker Cura is more accurate and precise. There is also a lot of possible optimization for the printing process and the most important one is the precision you want the printer to make your model.

It was really interesting, but I can’t export it in Gcode (the language of the 3d printer/laser cut). So, I tried to look for another slicer and my choice fell on the Ultimaker Cura, that is really interesting for more precise and smaller slices. It is not finished yet and there are still a lot of things to improve but I have learned a lot these days.

Ps: btw, the electrical transformer of my 3D printer just burnt and shut down all my attic lab electrical circuit. So yeah… Just because I forgot to NOT turn the voltage to 110v (European voltage is ~230 volts). I needed to put the voltage at 220v at least. Godammit, I should have been more careful.

What did I learn?

  • Using .stl extension binary exportation
  • Changing the custom .gcode of the 3d printer
  • Using Meshmixer, analyzing the geometry and non-manifolds fixing
  • Ultimaker Cura customization
  • How to make tree supports and for which cases
  • Electrical transformers are really useful, so just get another one just in case.
  • etc.

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