Week 05

I have little to none experience with 3D printing. I am familiarized with the variety of uses of it but have almost never 3D printed myself. Luckily, I was part of the MDEF Pre-course and got better understanding of it.And for the part of 3D scanning I had never done it before.

3D printing.

To 3D print you need to know and understand several things, one is how to make the model, making sure it is a closed surface, otherwise you won't be able to 3D print correctly. And the 2nd thing to know is understanding the settings and characteristics of each printer to make sure you use the correct one for your model. Also, you need to be careful with the angles of your model, making a smart design will save you time later.

One of the requirements for this assignment was that the design could not be done by substractive manufacturing as my design was comformed by 2 faced triangles in different angles all along a diamenter that would be almost impossible to cut with precision with a CNC machine.

I modeled a ring in Rhino and then exported to .stl, but when I tried to print it in the RepRap printer using Ultimaker Cura it won't let me, although I didn't undestand why, I thought it could be because of the small size but that shouldn't be a problem. Anyway, at the end I scaled it for it to be a bracelet instead of a ring and it all seemed fine.

After the file was ready, I needed to set up the printing configuration, I used the standard quality settings (preconfigured) and with a 0.8 mm wall. As I said before, you have to be careful with not go over a 45 degree angle because you will need to add supports to your model. Mine respected that rule so additional supports were not necessary and the waffle infill worked perfectly. Also, Ultimaker will show you a preview of how the layers in your geometry will look like and the time it will take to print and for this assignment planification was important as we were more than 20 students using the same machines for a week.

After saving the settings, I saved the file in the printer's SD card, got the printer readym checked that the material was the correct one, APL, and uploaded the file to the printer. The print started good, there wasn't any problem until it reached a certain height of the bracelet, the material seemed to "fall" in one side. It was weird because all sides were the same and only one was printed weirdly, like if the nostril was not melting well or extruding more material than needed exactly in that side every time it passed through it. Other than that, the rest of the bracelet looked great. Maybe the quality could be better but for that I should use another type of printer because the minimum layer height is limited by the extrusion diameter.

3D scanning

For the 3D scan I first tried the Kinect and Skanect software, but as simple as it seemed to use (connect the Kinect, open the software in the Fab computer, and start scanning really slowly until done), we weren't able to scan properly so I went for my 2nd option, ScandyPro. It looked pretty good and easy to use but when I downloaded it and try to use it, I felt the consequences of planned obsolescence and got the following message (Note: I own an iPhone 8, my classmates own an iPhone X or latest).

So I went for my 3rd option which was a software called Agisoft Metashape. Metashape uses photogrammetric processing of digital images to generate 3D spatial data and it worked! You basically need to take 360 degree photos from the object you want to 'scan' and the software will do the rest for you.

The first thing to do is download the software from this website. And install it in your computer, as you know, I am a Mac user and I had no problem with installation. The next thing I did was to decide what object I wanted to scan, but first I watched a quick tutorial of how to use Metashape, in this tutorial the guy shared some tricks to get a good scan from the first attemp, like good lighting, no shines or heavy shadows on your object and how to avoid picking up too much information for your 3D scan by trying to blurr the background in the photo or using a cardboard behind.

First I tried to scan a coark because it is small and had a cool texture although that worried me a little. I took around 112 photos with my iPhone from every angle kind of 'drawing' a sphere around it. Then, I shared the photos to my computer through Airdrop because is easier and you don't have to worry about the size or how many photos you share at the same time. Then, I opened Metashape and the steps to import the photos are very simple: Workflow >> Add photos >> (choose all the photos that you imported from you phone or camera) >> Open. Next, you want Metashape to start analyzing all the photos you took: Workflow >> Align photos. And the software will identify from what angle you took the photos. This step may take some time depending on the photos and your computer capacity, for me this step took around 23 minutes. The result was not really what I expected so I had to do it again but I used a padel ball instead.

After having all you images aligned the next step is create the mesh for your 3D object: Workflow >> Build Mesh. This step took around another 20 minutes so you can let that load in the background and keep working on something else. For the setting option I chose High Quality on both and the texture was really interesting on both, athough the corke was the most incomplete shape. I later realized that maybe lighting and shadows were playing an important role on the photogrammetric as, on both files, 1 side was incomplete. I got a great 3D model for the padel ball and I only took 58 photos, a lot less than for the cork and got a much better result. You have to be sure that the object is frammed almost the same in every picture.

Metashape offers some settings for deleting information you don't need just like I did and it also will let you create mesh over holes after deleting the base where I placed my object, for example. Once you're happy with the result you can export your 3D object as .obj to open in another software: File >> Export >> Export Model >> Choose the extension and folder to save. >> Export