One of the fastest-growing industry subsets today is the field of 3D printing, the ability to design an object virtually and then construct that object as a single piece using specialized tools and software. Blender is capable of creating 3D printable objects and then sending them to an application used for the 3D printing process. To make life easier, Blender has an add-on for helping to construct models for the purpose of 3D printing.
To activate the Print Toolbox Addon, first, go to Edit > Preferences > Add Ons, and in the search bar in the top corner type in print toolbox, making sure the tickbox is enabled before closing the preferences panel. To locate the toolbox, press the N key on the viewport to open the side panel, and select the print toolbox tab.
This is perhaps the single most important add-on that you can use for 3D printing in Blender, but what exactly does it do and how can it help to construct printable 3D objects?
What Is The 3D Print Toolbox Actually Designed To Do?
The 3D print toolbox is designed primarily to identify geometry that is likely to cause issues with the printing process. 3D printers are limited in their capabilities and so as the designer of the object you need to ensure that the model falls within these limitations. An example of such a limitation is the size of the model, as each 3D printer is capable of producing objects in a certain size range.
So the 3D print toolbox is able to accurately calculate both the area and volume of a selected model, which are the parameters used for defining an object’s size in 3D printing.
Equally as important is the ability to find geometry that is not suitable for a 3D printable model. This comes in several different forms and so the print toolbox is able to find which faces effectively fail specific tests. An example of this is finding overhanging faces that are not supported by the rest of the model.
While the primary purpose of the print toolbox is to identify problem areas of the model, it is also capable of cleaning up your geometry with the help of a couple of simple tools. However, it will only fix the geometry that it finds issues with, and we suggest other methods as well for actually fixing these issues, such as removing duplicate vertices.
Why Do We Need To Use The Add On To Identify Issues With The Model?
You can easily get away with poor topology for your 3D models in a rendered image or animation, so long as it does not have a noticeable impact on the models’ appearance or animated movements. When creating a model for use in-game design you have a few more parameters to consider such as the topology, normals, and density of the geometry.
But 3D printing takes things a step further because you are telling a machine (the 3D printer) to create the exact object that you design. However your design may not be practical for a 3D printer to create, or it may have issues with the geometry which can always impact the final result.
It is very easy to design a model for virtual purposes, but much harder for creating actual physical products. Getting a model wrong for a video game simply means importing the model back to Blender, and editing it so that any errors are corrected, before sending it back to the game engine.
By contrast, a 3D printed model requires a significant amount of time to create, as well as cost for the materials used for printing. As you can tell, messing up a printed model can be costly, both in terms of time and money.
Is it Ok If My Model Is Not Perfect For 3D Printing?
It is unlikely that your 3D model will ever be truly perfect, especially if you are adding more detail, like with sculpting for example. The idea of the 3D print toolbox is so that you can control the threshold at which faces will be deemed no longer usable, as there is no definitive value, this falls on the hardware that you are using.
If you are using your own 3D printer at home or in your business, then we recommend researching the limitations of your selected printer, and possibly creating some dummy models to test first. When you send your model to the software used to create the actual 3D print, the model will need to be suitable for 3D printing but does not need to be perfect. Remember that there are parameters that your printer will be able to work within, so there might be a tiny bit of leeway.
Selecting The Geometry In Edit Mode
Before we break down the purpose of each option in the toolbox, we want to highlight the ability to select the geometry that falls into one of the categories in the checklist. We do this by first selecting the check all button in the toolbox to view our categories.
Then we transition from object mode to edit mode, and when you do you may find that some of the options transform into buttons if the value is greater than 0. If for example, the nonmanifold edge becomes available, then you can click the button and all edges that are classed as nonmanifold edges become selected on the model.
The same applies to any other options in the list, such as selecting non-flat faces. This allows you to actually identify where the problem geometry is on the model.
A Breakdown Of What You Can Do With The 3D Print Toolbox
There are numerous potential limitations that can hinder the creation of a good 3D model, so below we have a list of what limitations the 3D print toolbox can help identify:
Volume And Area
First, you have the ability to calculate the volume and area of an object, as these are important for defining the size of your model when printing.
The area of a 3D object is the surface area of all of the objects’ faces combined. For example, a cube has 6 sides, and every side is 2×2 meters in size. So 2×2=4 and then 4×6=24, meaning that the area is 24 meters squared.
Volume on the other hand is the area that the object itself takes up. While area takes the height and depth of each face and adds all the faces together, the volume is the height * width * length of the object. In the case of the cube where all sides are 2 meters, this reads as 2x2x2=8, so the volume is 8 meters cubed.
This should be fairly straightforward. Any real-world object that is created and has a defined shape needs to be a solid object. This means that all parts of the object need to have some level of thickness, which can be created through extruding or by using the solidify modifier.
The normals of the object are also important, which represent the direction that the vertices, as each vertex has a ‘front-facing side’ that needs to be visible to the printing software.
Clicking will tell you if there is any nonmanifold geometry, which means any geometry that cannot exist in the real world, like a flat face extruded out of a box.
It also indicates if you have any bad contiguous edges, which are edges of the model that are facing the wrong way. In other words, the normals of the vertices used to create these edges are incorrect.
To correct this you can select all your geometry, use the hotkey Alt + N and then recalculate the normals to face outwards.
This is one of the more difficult ones not to spot naturally and is when you have two or more faces that are intersecting each other on the object.
This is most likely to occur on abstract objects where a randomizer tool has been used to shape the geometry. This is a killer for 3D printing so you need to make sure that you have no intersecting faces on your model at all.
At face value, you may not know what the term degenerate is, but it is actually very important for 3D printing. The term degenerate here applies to any geometry whose size leaves it outside the printable range of your 3D printer, or of any value that you determine.
The focus is on locating what are known as zero faces, which are faces that are too small to be printed. This is the first tool that you can control in the toolbox, as it allows you to set the minimum value that an edge or face must reach to not be considered a degenerate piece of geometry.
The values here are connected to your chosen unit of measurement for Blender. In my case, I use meters as my UOM (unit of measurement) so the value of 0.00010 is equivalent to 0.1mm. If you know what the minimum value is for your 3D printer, then you should set this to the same value, or slightly higher.
The individual faces that make up your models should generally be flat, but this is not always the case as moving individual vertices around will affect the faces that they are used to creae.
This is one of those where you do have a slight bit of leeway for distortion but the best way to avoid it entirely is to increase the density of your geometry, as smaller faces are less likely to be heavily distorted.
Be careful not to go too small though as you still want to be able to edit your model without difficulty, The value used to define distortion is set to degrees by default.
It is set to 45 degrees by default, increasing the value increases the threshold for allowing more distortion on your model, while lowering the value makes the tool more sensitive for located distorted geometry.
When you are working with a very small object, you need to ensure that there are no parts of the object that lack the thickness necessary to be printed.
For example, you design a character with extended fingers. The design may look good, but if the thickness of the fingers is too small then they will not print correctly.
The minimum thickness is set to 1mm, but many home-based printers go as low as 2mm, so check the specs for your machine and then set the value accordingly.
A perfectly sharp edge does not exist in the real world, but it cannot be avoided in 3D modeling. What you can do with your models however is reduce the angles that your edges create to generate a smoother appearance.
Two tools that can be used to reduce that sharp look for your model are the subdivision surface modifier and the bevel modifier.
You can set the value of the sharp edge indicator to any value in degrees to highlight if there are any edges that have an angle equal to or greater than that value.
A basic cube for example has 12 edges and each edge has a value of 90 degrees for its angle. Set the sharp edge value to 90 and select check all, then you will see that the object has 12 sharp edges. Set that same value to 91 and check again, you will find that the number of sharp edges has been reduced to 0.
Higher density objects are less likely to have edges with greater angles, and an ideal value to keep below for printing is 60 degrees. Again you can use bevels to achieve this on your model.
When an edge or face is overhanging, then that means it is in a position where it is not directly supported by the rest of the model.
While it is perfectly possible to print with overhangs, there is the risk of structural weakness in these areas of the model. That means that you are most likely to break the model where there are overhangs.
You may not want to change your model though as having overhanging faces may just be a hazard to your chosen design. What you can do instead is set up your printer outside of Blender to create support material, which can be cut off easily after Printing.
This tool can be used alongside the volume and area indicators and is very handy if you are working as a business for creating 3D printable models. Say for example you are designing figurines and all of these figurines need to be of a certain size.
The ‘scale to’ tool can be used to adjust the volume or area of the model to a specific value. This is a great way to ensure that your products are all the same size or thereabouts.
When you have identified all of your non-manifold geometry, you will be able to use the clean-up tools to get rid of the geometry. Note that this is not a perfect tool and while it will reduce the number of nonmanifold edges on your model it may not eliminate them all depending on the model’s shape.
You should look to combine other tools with the clean up option to make sure that your object is in the best shape possible.
Finally, the addon allows you to export your 3D model as a file format that is suitable for the 3D printing process. You have four options to choose from and each is slightly different but all effective for 3D printing. These formats are:
The obj format is best suited for beginners as it limits the export to simple geometry data, but we tend to use the STL format for objects that we want to prep for 3D printing due to its versatility with the data it stores.
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