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With the cost of 3D printing plummeting and it becoming more accessible every day I have been itching for more things to print. And so when I finished the recent tutorial for 3D Artist magazine on creating a Pteranodon in Blender, I thought it would make for a great printing piece. Not only does it make a cool figurine, but it’s also a good stress test for printing. There’s very thin areas, thick areas, and everything in-between. I’ve been a big fan of Shapeways for a while and so I decided to print through them. In doing so, I thought some of you might find it valuable, or at least interesting, to see some of the process.
Preparing the model for printing
The first step in printing a model is to prepare it for the printing process. When working in Blender (or any other surface modeler), we’re free to make the meshes anyway we choose. But 3D printers are more strict in the meshes they can work with. They must be water tight, fit within the bounding box of the print bed, and they need to take into account the limitations of the chosen printer.
Making the model water tight
In order for the printers to printer the model correctly, it needs to be water tight. Meaning there cannot be any non-manifold edges in the model. Everything has to have thickness to it. In the case of the Pteranodon, this meant I needed to combine everything into a single mesh. I could have done multiple parts, but generally that’s only done if you wish to have moving parts. To combine all of the meshes together I just used Union Boolean operations.
This can be a tedious process with complex models, as booleans are very slow in Blender when working with complex meshes. But it’s a lot easier than trying to do it by hand. In doing so, you also need to set aside everything you’ve ever learned about good topology, as it all goes out the window when printing. 3D Printers don’t care about topology, they care about water tight forms.
Scaling the model
Since we’re translating a model from the digital world to the real world, we need ensure the scale is correct. Not only do we want to avoid accidentally printing a minuscule model, we also want to mitigate costs. The larger a model the higher the price, generally. Most printers also have a fairly small print volume, so if a model is too big it’ll be rejected by Shapeways. Thankfully Shapeways has done an excellent job of making it easy to check the maximum print size of the chosen material. Just check the Max Bounding Box per material: https://www.shapeways.com/materials/strong-flexible
To check the model size in Blender it’s easiest to use the Metric unity system. I find this easier as one meter is the same as one Blender unit. Blender allows you to switch the unit system used via the Scene properties.
Once the mesh is water tight and scaled, it’s time to check thickness. As with the scale, you need to be aware of the minimum thickness that your chosen material supports. If you’re printing on your own printer, then check the resolution capability of the printer. If printing through Shapeways, like I am, then simply check the materials page for Minimum Wall: https://www.shapeways.com/materials/strong-flexible
When printing through Shapeways, they carefully check your model after uploading to ensure it can print. It first goes through some automatic checks for basic compatibility, and then is reviewed by hand for thickness. If an area is too thin they’ll notify you of the problems. In my case the tongue, lower beak, and a couple areas of the wing were too thin. Causing the pteranodon to be rejected the first time. Fixing these issues is pretty trivial. I just used the sculpting system’s inflate brush to enlarge those areas slightly. Measuring the exact thickness is a little more tricky, though. Generally I will either use the Ruler tool or temporarily connect two opposing vertices with an edge and check the edge length.
Checking the model balance
With the mesh water tight, scaled, and checked for thickness, now comes one of the most important, and most easily forgotten steps. Checking whether the model will stand as intended. The first time I printed with Shapeways, I didn’t put enough thought into this process and my resulting model had to be propped up. Otherwise it just falls over. It was a print of Melvin from Eat Sheep.
It’s easy to forget this step, but it’s really crucial to a quality print that you’re proud to show off. Luckily, it’s also very easy to test! The rigid body simulation tools work perfectly. Simply add a ground plane as a Passive rigid body, and then add an Active rigid body to your print object. Once the rigid bodies are added, raise your model off the ground a bit and then run the simulation. If the model comes to a rest in the correct stance you’re probably good to go.
For an even better test, tilt your model at and angle to better simulate dropping it. If it still comes to rest correctly you’ve got a good base.
Exporting to STL
After the above steps are complete, it’s time to export the model. This is very straight forward. Simply select the model and go to File > Export > STL (.stl). Or if you’re using the 3D Print Toolbox addon that’s bundled with Blender simply set the path and press Export. You can also use this addon to check for errors within your mesh.
With the model exported it’s time to send off to Shapeways.
Printing the model with Shapeways
The final step in getting the Pteranodon printed was to upload it to Shapeways and order it. At this point Shapeways will run some automated checks on your model to ensure printability. If it passes the automated checks they’ll also double-check it by hand before sending it off to the printers. As noted above, if it fails the hand checks, as mine did, then you’ll need to fix the specified issues. I had a few areas that were too thin, so I fixed them and then re-uploaded.
Once all checks are complete it’s sent off to the printers, which brings about the worst part of the process. The waiting and anticipation. Most orders through Shapeways take 2-3 weeks from ordering to delivery. This is really quite impressive, considering the volume they’re printing, but patience is difficult when you’re excited!
Soon as the model is uploaded and accepted, you also have the opportunity to add a description, additional photos, etc. You can also choose to make it publicly available for purchase. Any one that wants a print of your model can order it directly and Shapeways will print it on-demand.
Speaking of which, the Pteranodon is available for purchase! Get your own figure to watch over your desk.
Modeling for printing tutorial
If you’re interested in getting your own models printed and want more details on the steps necessary to prepare your models, check out my full tutorial on the subject. It takes you step by step through the process of creating a 3D printable model, including size, wall thickness, escape holes, and exporting.
At the end, you’ll be able to order your very own Suzanne or print it on your printer.