File formats for 3D printing
All 3D printer / stereolytography technologies require triangulated polygon objects.
Two of the most common formats we work with are STL and OBJ.
All 3D modeling programs (capable producing polygonal objects) can save in at least one of these two formats.
Preparing files for 3D printing
A model created for 3D printing must meet more requirements than a model made for CNC routering or hotwiring. We can assess your model to see if it is fit for 3D printing. If your model will not meet the requirements for 3D printing, we can help you tweak it. Here are some pointers when creating a model for 3D printing
Wall Thickness and Volume
Depending on the 3D print technology, object size and other variables – wall thickness is very important. If the object is a good and watertight model, we can hollow it out to give it a wall thickness that prints properly.
“Watertight” basically refers to one interconnected shell with no holes. Imagine the entire surface holding water and not spilling a drop. If the object is built up from multiple shells, each individual shell would also need to be watertight. If you model a blackberry out of small spheres, merge (Boolean) the surfaces together to form a watertight body. You could also submerge many small unbroken spheres into others to make up the body of the blackberry.
If, however, several half spheres (open on one side) were aligned so they visually form the blackberry, it would need to be fixed or remodeled.
Fit for 3D print?
Unfortunately not every object is fit to be 3D printed. It may be too large or the details too small for the 3D printing process.
The “support” structure may ruin the surface. Depending on the shape, we have to support some parts of the object during the printing process. If you imagine a tree, branches grow upwards and angled slightly sideways…they never grow downwards. Now imagine slicing the whole tree horizontally into thin slices. If you want to build up the tree again, you can start with the lowest slice and glue all the slices onto each other in the right order to get the original tree shape back.
Now imagine the same tree with one branch growing slightly downwards. After slicing it up, you would have problem assembling that one downward branch. The first slice – at the outer tip of the branch – would be in the air. So there is nothing to hold it. You could cut a small pillar at the right height and put under the slice and starting stacking the other slices on top. As you stack on top of each other and a bit sideways, you would have to put several pillars underneath this branch so it doesn’t tip over.
These pillars are the “support” structure. Depending on the object there can be many of these pillars, walls, pins and other shape of support. After the print is completed, all the supports need to be removed by cutting/breaking them off. The point where they were attached to the object leaves a small mark.
If the objects shape is blunt or smooth and organic, these small dots can easily be sanded away bit sometimes these dots can ruin the surface, especially if they occur where there is lots of small detail. That is why planning is important in the modeling stage. If in doubt, ask us for guidance. We are happy to help.