Week 5:
3D Scanning and Printing

Mission objectives:

Show how you designed and made your object and explaine why it could not be made subtractively.

Test the design rules for your printer (group project).

3D scan an object (and optionally print it).

Outline problems and describe how you fixed them.

Include your design files and "hero shot" photos of the scan and the final object.

Printing final project miniature model.

Material: PLA
3D printer: Bq Hephestos 2

Modeling

For this assignment I decided to 3D print mini model of the final project with one turnable hinge.

The mission is to simulate the motorized axis that will correct the position of the light concentrator with the altitude of the sun daily path. The dish has to turn around the grill and to keep the focal point on it. At the same time the grill should stay stable during the movement.

Print file preparations

Creating the model was the easiest part by using the Fusion 360. Exported from Fusion STL binary file wich was later used with Cura to prepare the model for print.

Cura was my software choice for checking the model before the print and for converting the meshes in to G-code. From Cura the G-code has been exported to flashcard that fits the 3D printer.

At my first attempt the diameter of the dish was 50 mm and the thickness of the parts was about 1.5-2 mm. that was the first mistake. Too thin parts for the machine resolution capabilties.

Printing

3D printing process video

I made a mistake also by nesting all three parts at the same print file. They were to far one from another.
For my surprise the hinge did work and the grill part was fine but the dish came out broken in two parts in the middle, between the layers and the stand messed completely because of the retraction between the layers.
The "non printing travel speed" was 150mm/s, but the retraction parameter wasn’t accurate enough.
The head run out to other part after each layer and the PLA became too cold to stick to itself when it came back for the next layer. That caused bad joins between layers and retraction.

For the next attempt I scaled the parts 1.5 times bigger and sent the parts one per each print. That worked much better. This time the wall thickness was defined as 2 mm and the in-fill as 80%.

Cura path simulation vs real print reference

I was very surprised and queries to find printed pattern/ornament that was mathematically created by the machine path G-code. It looks like elliptic loops between the layers. I used to recognize that optical effect as moire pattern illusion on the screen or as bad render quality or as screen side effect. At first, when I saw it, it just caught my attention for a second. Only during the documentation process i realized the potential that appears from the random and unplanned visual patterns.

3D printed model video

The axis is square and the dish has cylindrical hinge extensions that rotates perfect on it. It could be possible but pretty complicated to create those perfect joints at such a small scale without 3D printer.

Group assighment

Printer tests

In case of testing our printing machines we downloaded scale-test files from Tinkercad site in tense measure and to compare same PLA material with same printing preferences printed on two different printers.

Scanning and Printing

For the our common assignment we decided to scan each other with the available 3D scanner to make a statue of three of us together - totem of the class 2017.

During the scanning we realized that it is much easier turn ourselves on an office chair than to walk around the scanned person.
There should be one “clean circle shot” - without to much overlapping of the same scanned area/surfaces. The overlap scanning creates blurred compilation between both of the meshes, one from the first take and second from the same angle overlap, when you make more than one complete circle around.

As a FabAcademy team we had an exceptional opportunity to print with to of the best table 3D printers in some outsource Lab/Garage. Form 2 is STA printer that uses UV light to fix liquid substance. Something like the dentist with UV gun fixes the tooth filling.

We used the scanner of Sense site in tense measure and to compare same PLA material with same printing p, handheld one, to create 3 different mesh files. We edited them in Rhinoceros and exported the single mesh file in to Cura to extract the G-code for the Hephestos 2 printing machine.