6. 3D Scanning and printing

Assignment

  • [x] group assignment: test the design rules for your 3D printer(s)

  • [x] individual assignment:

  • design and 3D print an object (small, few cm3, limited by printer time) that could not be made subtractively
  • 3D scan an object (and optionally print it)

Summary

3D scanning and printing: quite a new world for me… What I learned here is to set-up and use a 3D printing machine, understand its limitations and requirements…

Files are available here

Group assignment:

We tested the different printers available @Fablab ULB:

Tested 3D printers

Torture test models

Testing the Prusa i3 MK3

We made these 2 configurations with the printer

  • 0.20 with Filament-PLA-silver (1.75mm, 200-220°C) with no support and no brim,infill 20%
  • 0.15 with Filament-PLA-silver (1.75mm, 200-220°C) with no support and no brim, infill 20%

Results
0.15 mm 0.2 mm

For both settings the results are really good!

  • There is no major defect
  • The cantilevered parts are especially impressive
  • There is no welding for closed parts
  • The vertical pins can be printed almost entirely

The difference between both parts is however very difficult to see. The main clue is in the inclined plane: It is smoother for low angle (~15°) for the second configuration, with the thinner layer thickness.

Testing the Up! Plus 2

  • 0.20 with Unic-PLA-Red (1.75mm, 180-210°C) with no support and no brim, infill 20%

Result

The results are also quite good!

  • Even with the no support settings, the printer adds some support for the first Layer
  • The geometry is quite smooth (really good on the inclined plane)
  • The text renders with a lower quality, as the vertical pins.
  • There is welding with the 0.2 mm clearance.

Testing the Form 2

  • Layer height was set to 0,05mm.

Result

The Printing time in much longer with this technology. Even if the resolution seems lower than for the other printers, some defaults can be noted:

  • The bottom layer is filled and the hole in it is closed.
  • Some small patterns are not well rendered (small clearance is welded)

Individual assignment:

Design and 3D print an object

To use the Prusa i3 MK3 printer on my PC, I had to install the software and drivers. Software includes SLic3rPE and Pronterface. The latest software is useful when there is no SD card reader on the PC, as it allows to send the files to the printer through an USB connection.

I took some time to print the FabLogo made in week03, as this structure can not be made substractively, eg by milling with a CNC machine, there are undercuts and nested surfaces.

The first configuration of the printer is as follows:

  • filament type: Prusament PETG, diameter 1.75mm;
    Heating temperature is then 250 for the noozle/80° for the heatbed
  • printer: Original Prusa i3 MK3 (noozle of 0.4mmm)
  • printing parameters: layers of 0.15mm, first layer set to 0.2mm to improve adherence to the plate;
    filling percentage of 15%;
    no additional support.
3D Preview

Nearly 3h later: FAILED! For such a ‘big’ structure, without support, the overhang is too big:

Let’s print the structure with supports, in the following configuration, rotating the structure to place it on one of its corner (rotation of 45° around X + 45° around Y), to allow support from the heatbed directly and only:

  • filament type: (no change);
  • printer: (no change);
  • printing parameters: layers of 0.15mm, first layer set to 0.2mm to improve adherence to the plate;
    filling percentage of 15%;
    with additional support (see preview).
3D Preview

Nearly 6h later: Good!!!

When I’ve been asked to print a object that can’t be made substractively, eg a ball with hexagonal holes, as found here, I first loaded the stl file in FreeCad to check its dimensions, measured to be about 2.5x2.5x2.5 cm³:

But it was impossible to open it in my Slic3r software: And that’s why I made the Fabacademy 3D logo!

Update 14 june 2019

I asked [Christophe]((http://fab.academany.org/2019/labs/ulb/students/christophe-reyntiens/) to open the stl file of the ball with its Windows 10 PC....and it worked !!
We doubled the size of the ball to reach a volume of about 50mm diameter. The ball is resting on a really small surface, so, when we first tried without support nor skirt or brim, it FAILED !
We added a skirt of same width as the ball’size, and…yeah, it WORKED !!

Without skirt With skirt

I also decided to print the 3D scan of myself, just done with the 3D Sense scanner (see below). As it takes some time to print (about 9 hours…), I decided to put the files on a SD card, using an USB card reader…

First step is to import the OBJ file, and to re-dimension it (to 25% of the original size) to fit on the printer plate.

original size reduced size

Different parameters may be changed, the main ones are:

  • printing parameters: layers of 0.15mm, first layer set to 0.2mm to improve adherence to the plate;
    filling percentage of 15%;
    no additional support.

  • filament type: Prusament PLA, diameter 1.75mm;
    Heating temperature is then 215° for the noozle/60° for the heatbed

  • printer: Original Prusa i3 MK3 (noozle of 0.4mmm)

Once everything is fine, we export the G-code and save it on the SD card…

A few hours later, here is the result:

front back

3Dscan an object

Test of Scann3D on my Fairphone

Although the photogrammetry looks nice at the beginning, I failed to scan a simple object, due to the practical conditions: it is indeed difficult to move around the object in order to build a model of the object, just holding the smartphone.
Here is the best result up to now:

Test of 3D Sense

The 3D Sense scanner requires a PC running on Windows 10 (Windows 7 is not supported anymore with the new version of the scanner), so I needed some other PC than my usual one…

Installation is quite straightforward…

To ease the scanning process, the user needs to walk with both the PC and the scanner in hands around the subject. As the mesh is constructed while scanning, several passes can be made to ensure that there are no holes left in the image/mesh. Funny pieces reassembled to make a complete puzzle!

To finalize the scanning and create a flat base, in order to print the subject, a horizontal line can be drawn on the image, and the software generates automatically a flat base along the line.

The result is quite good…

Original OBJ is available here

Still to do if I had time....

I’d like to print my pentagone ball! I have the file ready, done on Christophe’s PC. We had to add a border, as the support surface was to small, first print without support failed…