Week 5
For this week, Antti, Kenichi and I worked as a group to test the design rules for three different 3D printers existing in our FabLab. We used Test your 3D printer file (Figure 1), as the test design for all the 3D printers that were tested.
Figure 1. Test your 3D printer file
The file includes 21 tests. These cover all tests available on the FabAcademy, except for the infill test.
MakerBot Replicator 2 is a form of 3D printing technology with 100 microns resolution (as thin as a standard sheet of copy paper) which has the fastest speed in printing among tested three machines. Two most common materials for printing with the MakerBot printers are ABS (acrylonitrile butadiene styrene) and PLA (polylactic acid), but MakerBot Replicator 2 is optimized only for PLA filament.
Figure 2. MakerBot Replicator 2 in Fablab Oulu
Pros and cons of ABS are as following:
In Fablab Oulu, we use PrusaSlicer software for this 3D printing machine which supports .stl, .obj and .thing . For printing, you just need to import files >> adjust and slice >> print.
Figure 3. In the middle of printing process (left) and removing the printed test from MakerBot Replicator 2 with a spatula (right)
The technology used in Stratasys Fortus is Fused Deposition Modeling (FDM), additive manufacturing process printing from bottom to top, layer-by-layer (each layer with each corresponding model material and support material).
Stratasys Fortus 380mc: Since this printer can work overnight and run automatically without supervision, it can be the best choice for printing objects with complex structure.
Figure 4. Our instructor, Behnaz, is explaining to us how to work with Stratasys Fortus 380mc 3D Printer
For preparation and sending printing order, we used GrabCAD and Control center. In GrabCAD, after importing .stl file, there was an unwanted part of support in the design. To remove that part, go to Support Settings->Support Style-> Sparse.
Figure 5. Removing unwanted support part of the design in GrabCad
When printing is over, you should wear a pair of gloves (beacuse of heat) and take the base sheet with the printed test. Then, try to remove the printed object smoothly from the base shit with a spatula. Finally, put the object in the tank containing sodium hydroxide, NaOH to soak which usually take 8 hours (at least).
Figure 6. Post-printing actions with Stratasys Fortus 380mc 3D Printer
Formlabs is based on Stereolithography (also known as optical fabrication, photo-solidification, or resin printing) technology. It is an additive manufacturing process where a laser beam builds up a model layer by layer from liquid polymer that hardens on contact with the laser light.
Figure 7. FormLabs Form 3 in Fablab Oulu
The software used for FormLabs is PreForm and supported files are .stl, .obj and the output file would be .form.
After printing, the model was first cleaned in Isopropyl alcohol, and then cured in 405 nm light.
Figure 8. Post-processing in Formlabs Form 3
The following tables show the different features measured with the printed objects from three different 3D printers.
Figure 9.Printing results from different 3D printers
According to the resluts, MakerBot Replicator 2 was the best for overhangs and minimal distance, while Stratasys Fortus 380M sounded the best choice for rounded prints. FormLabs Form 3 had the best results in complex shapes (name/text) and in general, Stratasys Fortus 380M was the best among three printers.
For 3D scanning, firstly, I decided scan a blue bird statue by Makerbot Digitizer, but Mikko warned me it would not be succesful because the object is shiny. He recommended me to use Photogrammetry which has a simple function of recaping several pictures taken from different angles by your camera or phone. I started to take pictures with my cell phone and put the object on a catalogue to ensure of the random pattern of the base sheet. But I was not happy with the angles and accuracy of each move I made with the base sheet.
Figure 21. Taking photos of the object with cell phone for Photogrammetry
To dicrease the risk of scanning a shiny object, I decided to change it to a cat mosaic Barcino statue (Gaudi Style) which was a souvenir from beautiful Barcelona.
Figure 22. A cat mosaic Barcino statue (Gaudi Style) finally selected for Photogrammetry
So, I discussed the problem with Mikko and he suggested me to use a gimbal called DJI Osmo which provides a steady position and angle of the camera that I needed for Photogrammetry. I attached my phone to the device and downloaded the related app which is called DJI Mimo. Then, to optimize the angle of the camera, I put the object on a box to elavate it and then, fix it to the base which was a catalogue.
Figure 23. Taking photos from the object with a gimble (DJI Osmo) for Photogrammetry
Next, I started shooting and after each photo, I moved the base slightly and took a new photo. Finally, I turned the object all around and took 59 photos of it form different sides.
Figure 24. Taking photos from the object with a gimble (DJI Osmo) for Photogrammetry
After finishing shooting, I tried to recap the photos and as it was recommended in the instructions, I started to use Colmap for Reconstructing geometry from photos. I followed this turorial as following:
When Colmap finishes the reconstruction, you’ll be presented with a reconstructed view of the scene and estimated positions of the camera.
Figure 25. Colmap set-up and finished view of the reconstructed scene
But there were no fused.ply and Meshed.ply files generated in the workspace folder as explained in tutorial. So, I decided to try Autodesk Recap Photos. It has very simple instructions to use. Just launch the software and from Dashboard, go to Create 3D->Object and choose yuor photo. Then, choose Add photos and finally, Create.
Figure 26. Autodesk Recap Photos interface
But you must be patient since it is cloud-base and it might be some oher works on the queue. For several hours, I only saw "Waiting in queue... 1%" (Figure 27).
Figure 27. "Waiting in queue... 1%" for several hours in Autodesk Recap Photos
Finally, the 3D scanned object was ready although there were some extra parts needed to be removed.
Figure 28. 3D scanned object in Autodesk Recap Photos
I simply used the edit bar from left side by going to Slice and Fill and adjusting the axis to be sliced.
Figure 29. Removing the background in Autodesk Recap Photos
At the end, I just remained the object without any background.
Figure 30. Final result: Processed 3D scanned object in Autodesk Recap Photos
During this week, I got familiarized with three different 3D printers we have in Fablab Oulu and their advantages over each other that was very interesting. Also, I learned about some 3D scanners and their functionality through the inclusive explanations of our local instructor, Behnaz. Then, I designed a 3D model to print it from a 3D printer and also, 3D scanned an object with Photogrammetry, all for the first time.
