3D cross-section

3D printing solid parts

This last Monday evening, I went to the Hillsboro Public Library 3D Print Lab to get one of my longboard footstop designs 3D printed. I was concerned my design wouldn’t meet their requirements because I had done nothing to minimize the amount of plastic it would need.

In preparation for the lab, I had downloaded and experimented with Meshmixer, a program for modifying .stl files. Meshmixer can automatically hollow out objects but I didn’t know whether the resulting object could actually be printed. After all, 3D printers can’t print on air; there must be a supporting structure. So I showed up at the lab with my original unmodified .stl file.

At the lab, I learned a few things:

  1. The program that drives the 3D printer is smart enough to create a temporary supporting lattice underneath an otherwise unsupported portion of a printed object. For example, if you want to print a sphere, the program would automatically generate the portion of a cylinder beneath the sphere as a support base. The program generates a weaker connection between the support base and the desired 3D sphere so the base can be removed from the sphere with some effort.
  2. Not all unsupported portions need a support lattice. Objects can expand out at up to 45 degrees before a temporary support structure is needed under the cantilevered portion.
  3. The program is smart enough to automatically hollow out solid objects, defining a minimum wall thickness and then filling the interior with a lattice to support the object’s top surface. The picture at the top of this post shows coarse and fine lattices.

In short, the program that drives the 3D printer is smart enough to solve these problems automatically. Cool!

Author: Brent Logan

Engineer. Lawyer. WordPress geek. Longboarder. Blood donor. Photographer. More about Brent.

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