Week 5: 3D scanning and printing

This week is dedicated to 3D printing/scanning, we have to scan an object and print an other object that can't be done by substracive fabrication.


Meshlab meshing

Study the limitations of a 3D printer (each machine has his own specifications.)

Design and 3D print an object

Scan an object

Extra: make a 3D scanner



Machines used and softs:

  • 3D printer: Makerbot Replicator 2X and Up by 3PPP.
  • Plastics: ABS from E3D
  • Software: Makerbot Digitizer, 123D catch by Autodesk, Meshlab, Meshmixer
  • 3D scanner: Digitizer from Makerbot
  • Foto Camera: Panasonic DMC-FZ38


  • Test the rules of your printer

    I fist wanted to do a quick review of the different printing options that exist.

    My test will be done on "MakerBot Replicator X2" , with ABS :

    Makerbot Replicator 2X

    When you want to print something, designing the 3D object is one thing, but then there are a lot of different parameters that we need to specifie to the machine.

    Like the layer height, the infill, the speed, do we want Rafts? Supports? etc


    The Infill

    I printed cercle with different infills, and I stopped the print so I could see the inside:

    0% infill 0% 5% infill 5% 10% infill 10% 15% infill 15% 25% infill 25% 50% infill 50% 75% infill 75% 100% infill 100%

    Then I used the printing information and made a graphe:

    Graphe infill

    Here are the data.

    We can see the printing at 50% infill is a good compromise between time, and structural strengh.

    And also that the function infill/time isn't linear, there is a big increase in time to pass from 75% to 100% infill.


    Layer Height

    This option defines the precision of you print, basicaly it defines the height of a layer of platics once it has been extruded.

    And it is directly linked to the number of layers and therefore, to the printing duration.

    I just choosed a random object on Tingiverse and printed it with different layers height:

    0.40 mm 0.40mm 0.25 mm 0.25mm 0.15 mm 0.15mm 0.10 mm 0.10mm

    We can see that as the layer height decreases, the surface gets smoother, but the print time increases.


    Other tests:

    Then I wented to push my tests a little bit further, so I tried to print really thin objects, intricated objects etc :

    thin wall 1 thin wall 2

    With this exemple we can see that the printer had some problems printing the last layers, that is because I tried to print something that was thinner than the actual thikness of the filament after extrusion.

    There is no way of making that thiner, so my solution here has been too slice the object and laser cut it:

    thin wall 3

    Design and 3D print


    CNC ? 3D printer ?

    My first assignment here is print an object that couldn't be done with a CNC machine.

    Here is a first exemple I found on Thingiverse:

    Hypercube

    It's a Hypercube, this object couldn't be made in the CNC machine.

    Last thing I would like to do is to design one myself.


    Different type of 3D printers

    I would like to indroduce 3 different printers just to show the main differences:

    -The Replicator X2 by Makerbot Makerbot printer Big printing volume, double extruder, 100 microns precision, little maintenance

    -The UP mini by PP3DP UP mini printer Very reliable, but small printing volume, almost no maintenance but calibrated for PP3DP filaments.

    -The Prusa i3 a RepRap that I made last year Prusai3 printer Can be personalised infinitly, best way to learn about 3D printing, requires a lot of maintenance.

    They are classified by the order of price, my prusa i3 was made for 10X less money than you would need to buy a Replicator X2.



    3D scan an object

    I decided to try different techniques of 3D scanning:

  • Using a camera and 123D catch (Autodesk)
  • And compare the results with a laser scanner : the Digitizer from Makerbot.

    Foto scanning (Foto-grammetry)

    This technique uses normal pictures to build a 3D representation of an object

    I decided to try the 123D catch software, this soft allows you to scan an object in 3D but you don't need too have a spinning table, you just need to be able to take pictures all around the object.

    I have decided to do my first test on a simple object :

    Photo oursin

    I red on the web that it is not adviced to try to scan symetric, glossy, or metallic objects, this one is clearly symetric but we wil see !

    I've send to 123D catch a total of 35 pictures but he didn't accept all of them:

    Pics total

    Since all the calculus are made in the cloud, you need to have a good internet connexion (with a proxy it doesn't work for me), the process may take a while:

    123D catch

    I will show you after how to fix those pictures that couldn't be used.

    But lets see the result first:

    Test 1

    I have to say that I was amazed by this result!

    We can even show from where the pictures have been taken.

    Position camera

    I zoomed in to show the level of detail:

    Zoom1 Zoom2 Zoom3

    You can also show the meshing:

    Meshing

    Then I selected all the background and deleted it

    Background delete

    When I was satisfied with the result, I exported my file in .obj, to open it on Meshlab.

    Meshlab import Meshlab texture Meshlab meshing

    The level of detail that I obtain is pretty amazing!

    Meshlab point selection

    Here is an other test I've made with my face:

    sacn of my face!

    I've then used Meshmixer to add some syle and work a little bit on the meshing:

    my face after meshmixer

    Laser scanning (Lasergrammetry)

    I then wanted to compare those results with a 3D scanner : the Digitizer from Makerbot.

    Digitizer+Replicator

    This device works by shining a red line laser on the object, the ligth refracted by the object is then recieved by a camera.

    Those refraction, once analysed, allows the software to create a meshing of the object.

    Before using the scanner, we have to calibrate it :

    Calibration

    Scanner -->Calibration and just follow the steps.

    So I first tried with the same object used for my other technique to compar the results:

    Photo oursin

    And here is the result of the fisrt scan:

    Photo oursin laser scan

    Here are the files without any post-process:

    File in .stl: Oursin.stl

    File in .obj: Oursin.obj


    Then I tried with more complex objects:

    Foto of the trex on the laser scan

    Here is the file of the 3D tRex skull:

    T-RexSkull_Jaw.stl

    T-RexSkull_Skull.stl

    The result after 3 scans:

    Trex first test

    I then wanted to add a box around the scanner to minimise the parasit light, but this was a mistake as you can see:

    Mistake Trex

    And also wondered to see what it would change to put the scanner in a dark room:

    Test in the dark

    I think it didn't change much, here are the files so you can compare:

    Test in normal conditions: tRex.stl

    Test in the dark: tRex(test).stl


    Here an other test with an object made in the past week:

    Test in the dark Test in the dark

    The file in .stl: construction.stl


    Now a test on a very complex 3D printed object (I printed it with a UP mini and the model is from Thingiverse)

    Crane 3D printed Crane 3D printed

    The file in .stl: skull.stl

    Here is the file of the original skull I used:

    skull03-sup.stl

    >Conclusion

    When I first saw the results I was surprised by the level of precision of the meshing, but when I tried to export it, I had my first bad news.

    The soft from Makerbot, allows you to only save your file as a ".STL" , ".obj" or ".thing", no problem would you say! Actullay yes! because the object we obtain is not the orignial meshing, but a processed mesh done by the soft! And the result is pretty disapointing.

    So in conclusion, I liked using both techniques, but I feel like the Digitizer is just a cool gadget to have in the lab, whereas, the fotogrametry is a whole science that you can practice just with a random foto camera!



    Make a laser scanner?

    An extra assignment is to try to build a 3D scanner, so I thought about different options:

    -Just build a spinning table with a stepper motor and use a normal camera,

    -Build a spinning table but using a Raspi camera and a laser,

    -Modelise and build a system that could allow me to take perfect pictures for 123Dcatch with an Iphone,

    -Use an Arduino ultrasound module to make a very simple 3D scanning device, I'm lacking time, so I'll go with this one!

    This is my first test , I didn't loose time designing a pretty case , I just wanted to see what precision I could obtain:

    Radar

    So first I ran it as a radar, just to see if my code worked , here you can see the result of my rand passing in front of the detector:

    graph radar1

    Then I tried fix objects:

    object used to test the radar

    At least we can see something:

    graph radar2

    Then I tried in a room:

    graph radar3

    And finaly I got red of the lines, and change the points mode to persistant, so I could try accumulate them and build a representation of a room:

    graph radar4 graph radar5

    As you can see this will not remplace the Digitizer or your foto camera, but as I didn't even calibrate it, I'm sure there are lots of possible improvments , like adding an other ultrasonic detectors.

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