Assignment 3a: 3D printing

Objective: print a small personalized cube
Time: 1 hour
Prerequisites:
  • Ultimaker2 3D Printer
  • Spool of black printing material
  • Software: 123D Design, Netfabb Basic, Cura

In this fab lab tutorial we learned how to use a 3D printer by printing a small personalized cube. Just like the laser cutter it felt great to be able to do this, although we quickly encountered some limitations.

1. Designing the cube

I designed the cube in 123D Design, a program that makes it very easy to create 3D objects. For our cube, you could just add a box primitive.

On Romains advice we created a circular whole in the box. This task seemed less intuitive but it made sense to do this in the end:

  1. Create a cylinder primitive (Primitives -> Cylinder) and put it on top of the box
  2. Extrude it (Construct -> Extrude) so that it is extended and that it covers the entire box.
  3. Remove the cylinder shape so that the whole remains.

I wanted to personalize more, so I added the following features:

  1. A small cylinder in the whole that forms a bridge between two surfaces.
  2. My name engraved in the cube. For this, I clicked the text button, chose a surface of the cube, and typed my name. After this, I could specify the texts size and depth in a pop-up menu next to the text.

We finished the design by exporting it to a fine Surface Tesselation Language (STL) file. This file is especially designed for stereolithography, the process of rapidly prototyping 3D models. In STL files the shapes are only described with estimated triangles. Thus, this process (also called tessellation) is just a rough estimation of the true CAD shape, although it gets better with the use of multiple triangles.

 

2. Analysing if the printing will work

In Netfabb we could then check if there were any problems with the surface. This is a very important step: if the shape is not checked, it could be not closed or not orientable, causing the 3D printer to have troubles or printing something wrongly.

For me this was definitely the case. My cylinder bridge was not closed and the engraved text was so deep that it reached the cylinder whole, creating a strange effect on the inside surface.

After about three new iterations, I managed to get through the test (Upper blue dot button ->  Standard analysis on the right -> Read results there).

4.png

Netfabb analysis.

 

3. Adjust last settings before printing

In Cura we could then adjust the last settings of the STL file.

These settings included the following:

  • Layer Height: 0.2 mm
  • Shell thickness:  0.8 mm
  • Retraction: enabled
  • Bottom/Top thickness: 0.6 mm
  • Fill density: 20%

We finished by saving the STL and creating a GCODE file (which however remained unused for the actual printing). All group member’s files were then put on a SD card.

5 (2)

Cura’s settings for the cube.

4. Et voilà, print!

First of all, the Ultimaker2 3D was turned on. We pressed Print and turned the wheel to select the folder with all our STD files.

The printer then obviously needed some material to print with. We picked a spool of black plastic at the lower part of the lab’s cupboard. This was put into the back of the printer, and the end of the line on the spool was put into the tube that lead into the actual the printing device.

We then pressed Material and then Change after which the material started to warm up to 220 degrees. Sometimes the machine stopped and we had to help the line of the spool by holding it into the right place of the tube. Each time after that, Print and the folder with the files was pressed again. This process ended when the plastic is « fat » enough, meaning it has just the right structure that it is liquid, but will dry to a solid form afterwards.

It was told to us that sometimes, the plastic is not good anymore due to temperature variations or its diameter. Also, the tube of the printer could be blocked. The printer then has to be cleaned three times by taking a line, putting it in at 180 degrees, and letting the temperature drop down to 90 degrees.

The printing process begun and unfortunately we could not see the result just yet. We could however confirm that the printed outlines lines looked flat and compressed, which was a good sign. We will see the result next time…

IMG_5842

Status of the printing after about 1 hour.

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