Week #06: 3D Scanning and Printing | Garner Holdsworth | Wheaton College, MA

Explained what you learned from testing the 3D printers

Documented how you designed and made your object and explained why it could not be easily made subtractively

Documented how you scanned and prepared an object (for 3D printing)

Included your original design files for 3D printing (both CAD and common format for 3D printing)

There are two major methods of manufacturing objects:

Subtractive: Material is removed from a larger body until the desired shape is formed
Additive: Material is deposited onto a workplane or support structure until the final shape is formed

In this sense, 3-D printing could be thought of as an opposite to something like CNC machining or hand-tooling, which allows 3-D printed objects to have internal complex geometries that wouldn't be able to be created in one piece if it were made using subtractive methods.

This is a print that was done to test the capabilities and limitations of the Prusa Mk3 printers we have here at the Wheaton Lab. Quality of the print layers and the strength of the print itself can depend on a variety of factors such as layer height, filament used, and speed of the print.

Using digital calipers, we tested the accuracy of a couple test prints to determine any difference between the dimensions of the model versus the final product. In every case I measured, the dimensions of the printed object was within a margin of error of 0.1mm or less.

I decided to create a Pythagorean Cup (also known as a "Greedy Cup"). This was a cup design from the same guy in Ancient Greece who made that one triangle theorem, and was supposedly used to prank greedy guests who took more wine than they were allowed to. The cup works by letting the contents of the cup into a tube in the center. Once the fluid level rises above the bend in the tube, the pressure difference created drains the entire contents of the cup through the tube like a siphon, spilling the victim's drink in their lap.

For the 3D scanning portion of this week's assignment, I had a couple of options;

LIDAR: The iPhone 13 Pro that I own has a lidar scanner that sends out IR (infrared) laser pulses, calculates the distance using the time it takes for the reflected pulse to return, and uses that data to construct a 3D rendering of the environment. This technology, while amazing for room-scale and landscape rendering, isn't very well suited for scanning smaller objects.
Optical: Using an app called Polycam, a 3D model of an object can be created from a series of pictures of said object seen from different angles and distances. A minimum of 20 photos is required for this particular program, but can more reliably create detailed renderings of objects, rooms, people, etc; with quality loosely scaling with the number of photos taken.

I tried out both options, but I couldn't get a clean 360-degree rendering of anything smaller than a chair with Lidar; so I opted for optical scanning instead, and selected my tape measure as a test subject.

By taking pictures while walking around the target object, the Polycam app constructs a 3D rendering of said object and its surrounding environment. It then allows you to adjust the boundaries of the render so you don't include any geometry you don't want. After that's complete, I saved a photo of the completed render seen here.

The app also lets you export the model for free, which was a godsend; this allowed me to import the model into PrusaSlicer and prepare it for printing, I did not print it though.