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From Blender to Slicer

Blender & STL – How to Make 3D Printable STL Files in Blender

Picture of Genaro Ponce
by Genaro Ponce
Jun 2, 2019

Almost every 3D modeling platform is able to produce 3D printable models, and Blender is no exception. Discover how to easily achieve good quality STL files using this more than can capable software.

Blender & STL What Is Blender?

The Blender website.
The Blender website. Source: blender.org

Blender is a free, open-source 3D modeling software used in many industries, including filmmaking, animation, and video games. It’s popularity stems from its capacity to handle complex geometries and different modeling styles.

When it comes to 3D printing, Blender performs exceptionally well. You only have to be aware of a few issues during the modeling process, and that’s exactly what we cover in this article.

Rather than give you a step-by-step guide of how the software works, we provide some useful tips that you can apply to avoid headaches during the printing process. If you want to give it a try, download Blender 2.79, which is the last stable version of the software and the one we’ll be using here.

For a plethora of other information on Blender, check out our related articles.

Blender & STL Setting the Units

Setting up your
Setting up your "workspace". Source: blender.stackexchange.com

Before doing any work at all, you should always adjust the units you’ll be working on in Blender.

Go to the properties bar in Blender and select the “Scene” tab. Below, you’ll find the “Units” section, where you should choose the “Metric” option and set the scale value to millimeters (or whatever units you want to use).

Now you’ll easily be able to match your model to whatever ideas or sketches you may have and be sure that the model you send to your slicer is the right size.

Blender & STL Patching Holes

Closing holes with the non-manifold option.
Closing holes with the non-manifold option. Source: blender3drecursos.blogspot.com

Important to have in mind when modeling is that your 3D model should be one solid mesh in order to be printed. (A mesh is a set of points, edges, and surfaces that describe a 3D object.) Otherwise, your 3D printer won’t be able to correctly interpret your model and it will fail.

To prevent this, you can manually check your model in Edit mode, selecting all the edges around a “hole” and pressing the F key. This will create an N-gon (a face with more than four edges) that closes that hole.

There’s another even faster way to fix holes. Again, in Edit mode, go to the Select menu, click on “Select Similar”, and then choose “Non-Manifold”. This will automatically detect and select all the edges surrounding holes, which can be closed by simply pressing ‘F’.

If the holes are too big, we recommend that you use the “Grid Fill” option; it closes the holes but maintains all vertices, meaning your model will keep its original shape.

Blender & STL Using Modifiers – Unifying Objects

Boolean operations in Blender.
Boolean operations in Blender. Source: blender.org

Blender has a number of modifiers that make the modeling process much easier. They can be accessed through the Properties bar in Object mode. Let’s start with the booleans modifier, with which you can unify, intersect, or subtract one solid with or from another.

As we need our object to be one solid mesh in order to be printable, it’s important to combine all components of our design into one. To do that, go to the booleans modifier and select one of the objects you want to combine. In the menu that appears, select the operation that says “union”, and in the Object tab, select the second object in the scene. This will make the two pieces one. Once you’re pleased with the result, press “apply” to make the changes permanent.

Blender & STL Using Modifiers – Solidify

Applying the solidify modifier to a surface.
Applying the solidify modifier to a surface. Source: spolearninglab.com

Avoiding extremely (or indefinitely) fine shapes while modeling is very important to preserve an object’s integrity. We recommend keeping a minimum thickness of 1 mm in all geometries of a model to guarantee that the part doesn’t break during or after the 3D printing process.

A very simple way to assure that your 3D model is thick enough is to use the solidify modifier. It allows you to apply a particular thickness to any surface using the specified units.

Blender & STL Using Modifiers – Remesh

Applying the remesh modifier in Blender.
Applying the remesh modifier in Blender. Source: blender.org

The remesh modifier remodels the topography of an existing mesh, simplifying the way surfaces are represented. Applying this modifier allows you to manipulate the mesh count without losing the original geometry.

This is very helpful when you have a model with too many faces, which is a common problem when importing models made using a different software tool. Setting lower values will generate a larger mesh while higher values will make the mesh more dense.

Blender & STL Using Modifiers – Reducing Polygon Count

This guy's looking sharp!
This guy's looking sharp! Source: blender.stackexchange.com

Just as with remesh, the decimate modifier also adjusts the topology, but with a big difference. While remesh respects the shape of the model, maintaining the vertices as much as possible, decimate will reduce the polygon count, removing “unnecessary” vertices and edges.

Naturally, this can either simplify a too-complex model or result in a huge loss of detail. In fact, this modifier is highly recommended to create low-poly versions of a model.

Blender & STL Analyzing and Exporting a Model

The Print Tool Box add-on.
The Print Tool Box add-on. Source: 3dprintingninja.blogspot.com

Finally we need to analyze and clean our 3D model to remove any faces, edges, and vertices that we don’t need. One way to do this is to remove doubles, which will automatically clean the model by minimizing the polygon count. In Edit mode, select the entire model (by pressing ‘A’) and open the Specials menu (by pressing ‘W’). Then, select the option “Remove doubles”.

If you want to analyze the model even deeper, you should consider getting the Print Tool Box add-on. It provides a lot of information that’s useful for the purposes of making a model printable. Apart from telling you the volume and area of a model, it can correct a design, indicating where the errors are. Other features include checking if the model is solid, if the faces are well-oriented, if thicknesses are correct, and if overhangs will be an issue during printing.

Finally, in order to transfer your model to a slicer, you’ll need to export it as an STL file. To do so, simply select “Export” in the File menu, and choose .STL. Hopefully, if you follow all the above, your model will be ready for printing!

Blender & STL Final Thoughts

A 3D printed model.
A 3D printed model. Source: Aenigmatis-3D / Pixabay

As you can see, there are several things that need to be considered before sending a Blender model on to a slicer. Blender is a formidable 3D modeling software, but it does require a bit of practice to get used to. Nevertheless, its many useful tools make it worth the effort, and with these tips, designing your 3D prints should be a breeze.

Feature image source: blenderartists.org

License: The text of "Blender & STL – How to Make 3D Printable STL Files in Blender" by All3DP is licensed under a Creative Commons Attribution 4.0 International License.

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