Week 3: 3D Scanning and Printing

Gyroid Vase

Oct 5, 2016

The Gyroid Vase

This week, the class was focused on 3D printing. Just like the laser-cutting assignment, I wanted to make something artsy, useful, and somewhat challenging to incorporate different skills. I decided to make a cylindrical vase with an exotic desing on its exterior. So I used Antimony's gyroid vase and made the interior a hollow cylinder. Scroll down for more on lessons learned, but here is the final prodct.


This week, we were assigned to test design rules for our 3D printer, then design and 3D print an object that could not be made subtractively. Additionally, we had to 3D scan an object.

Tools used this week: 3D printer, 3d scanner, Antimony, Fusion360.

Basic Knowledge

Fused Deposition Modeling (FDM) or Fusef Filament Fabrication (FFF): An additive manufacturing technology commonly used in 3D printing. Sindoh's 3DWOX printer and stratsys uPrint SE both use this technology.

Sindoh 3DWOX: One of the two printers available in EDS. 3DWOX is a desktop printer; it's chepaer and has less quality than uPrint, but better for rapid printing. It has an enclosed chamber that maintains termperature for better quality prints. After printing, support structure can be scrapped off with a knife. Note that if you have a model that requires support in-between moving assemblies or an inaccessible part, then you can't print the model with this pritner. Max build size is 8x8x8 inch3 .

Stratasys uPrint SE: The higher quality, more expensive printer in EDS. The advantage of this printer is the use of soluble support material, which allows printing moving assemblies, overhangs, and generally more complex structures. After printing is done, you pop the printed model off the modeling base and dip in WaterWash for half the time of printing at about 70 degrees celsius. WaterWash dissolves the support material. At the end, you wash the model with water. Max build size is 8x6x6 inch3 .

Materials used in 3D printing: PLA (polylactic acid) and ABS are types of plastic most commonly ussed in 3D printing.

Resolution of 3D printing: Horizontal resolution is the smallest distance the printer head can travel and the vertical resolution is defined by how small the thickness of a layer can be. 3DWOX resolution is about 0.050 inch and uPrint resolution is 0.010 inch.

Filament: 3D printers melt filaments of ABS, PLA or other material to 3d print a model.

Infill and shell: Infill is the interior structure of a 3D print model and shell is its exterior structure. 3D printed models are usually printed with an inner mesh rather than a solid structure.

Support: Support structure is needed when a layer of plastic must be deposited on a previous layer. Overhangs and suspended structures are among thigns that need support.

Post-processing: process of smoothing the surface of the model after 3D printing.

Stereoloithography (SLA): A form of additive manufacturing technology where a model is produced by adding polymer layer by layer. This is the basic technology in most rapid prototyping printers.

Subtractive vs. Additive design: Additive design is a design where an object is fabricated by starting from one layer of material and step-by-step adding more layers to form the final product. Subtrative design is a design that can be fabricated by startng from a block of material and carving pieces out to make the final product.

Design constraints: As a rule of thumb:

Mesh: In going from a 3D model to a 3D print, we need to create a mesh of the model. A mesh breaks down the model ito small shapes, like triangles. The mesh resolution is an important factor in printing. You can use software (e.g. Meshlab) to veiw and modify a mesh.

Mesh file formats: STL, OBJ, and 3DS are most common and useful.

Design software: For beginners, Neil recommended using Antimony, Fusion360 (free student licesnce available), or SolidWorks.

G-code: A programming language used in coomputer-aided manufacturing to control machien tools, with tool coordinates and tool commands. When using g-code on 3D print, usually color red represents build layers, blue suuport, and yellow the 3D mesh.

3D scanning: Generally, frustrating (proven by experience)! There are various methods such as tomography, confocal imaging, etc. For beginners, Neil recommended using Sense or photogrammetry. It's worth noting that going from a 3D scan model to a 3D print is a non-trivial step, since a 3D scan is not originally a mesh -it's a actually a collection of points.

Characterizing Design Rules for 3D Printer

To test the resolution and constraints of the 3D printer, we used a test piece designed previously by one of the TAs. This piece tests overhangs, sharp edges, thin walls, narrow spacings, and resolution of printing. We printed one volume on its base (picture on the left) and one volume on its side (picture on the right), using 3DWOX. Surprisingly, the estimated time of printing for the piece lying on its base was longer, since the hot end has to travel longer.

Here is what we learned: