Week 5: 3D Scanning and Printing

Our assignment:

Group Assignment: test the design rules for your 3D printer(s)

Individual Assignment: 1. design, document, and 3D print an object that could not be made subtractively (small, few cm3, limited by printer time) 2. 3D scan an object (and optionally print it)

Group Assignment

For the group assignment (linked here), Castor and I learned what 3D printers are available in FAB Lab Noda, learned how to configure the software PrusaSlicer, and tested our printers' design rules.

Printers: We have 3 different Prusa brand printers. 2 Prusa MINIs (equipped with 0.4mm and 0.6mm nozzles) and 1 Prusa i3 MK3S+ (equipped with 0.4mm, 0.6mm, and 0.8mm nozzles)

Software: We used PrusaSlicer to configure specific printers and filiments. For uploading print jobs and remote monitoring, we used Prusa Connect for the MINIS and OctoPrint for the Prusa i3MK3S+.

Configuring PrusaSlicer

We began by setting up Prusaslicer with the following configurations:

Mode: Expert Mode (offers more sophisticated fine-tuning)
Printer Selection: Chose printers listed above
Filament Profiles: We left the standard selections checked and made sure to include Prusament PLA / PETG, and Generic PLA / PETG. We should put specific brand here if we see it for future prints.

prusaconfig

Going through the configuration wizard

Running Tests
clearance tests

All three prints of the tolerance test design. Thanks Castor for photography tips and formatting ideas for this section!

For my part in the group assignment, I ran three tests of the same model using this online clearance tolerance test design by 3DMakerNoob on printables.com. This is a helpful tool for creating designs with moving parts (i.e. they have some type of small gap) so they don't fuse together. This website allows you to open the file directly into the PrusaSlicer software.

Each of these prints had 15% infill settings and used Generic PETG as the filament. The printer settings for the 0.8mm Prusa i3 MK3S+ (printed in blue) was 0.4 mm QUALITY; for the 0.6mm Prusa MINI was 0.25mm STRUCTURAL; for the 0.4mm Prusa MINI was 0.15mm QUALITY. Within the software, it was useful to experiment with slicing at different print settings to see if higher quality would be worth the additional time or to see if it made much of a difference in time at all.

Test	Blue (0.8mm)	Green (0.6mm)	Pink (0.4mm)
Print Speed	Fastest	Medium	Slowest
Stringing Test	lots of stringiness	less	even less
Numbering Test	unreadable	slightly defined, practically unreadable	all numbers readable
Clearance Test	Failed at 0.10mm	Passed	Failed at 0.10mm

Lessons Learned and Troubleshooting

Nozzle Size: The 0.4mm nozzle provided the highest detail, whereas the 0.8mm nozzle provided the fastest speed
Clearance Tolerance: The sweet spot for the blue print was within the 0.20mm to 0.25 mm clearance range (of course, depends on function of print). Any bigger, the embedded balls would too easily fall out and any smaller they were either fused or take too much effort to move. The sweet spot for the green was right at 0.15mm - 0.20 mm. The sweet spot for the pink was also at 0.15mm - 0.20 mm. But overall the balls did much better with not falling out when you shake the object even at the larger clearances.
Quick Tips: Use Shift+A in Prusa Slicer to center objects on the bed. Keep the default G-code file names provided by PrusaSlicer as they keep useful data about print settings used. The print bed can get up to 100 degrees Celcius! It's important to be careful

As a final note on these test prints, we did have to tend to a couple issues with the printer "gooping" and thus making our prints unworkable. When this started happening with one of my prints, I cancelled the job and Will showed me how to use the Live Adjust Z feature while re-running the print to ensure the nozzle is set at good distance from the bed so it doesn't goop.

goop pic

It dried up a bit but you can see where the print started to goop and mess with the design

3D Printing

3D print hero shot

My 3D print in 3 takes

For my 3D print, I decided to open up Fusion to design an enclosed box that has an internal feature and has lattice like faces so I could slightly see into the box.

I began by making the outer box shape, creating an inner shell, and attempting to sketch a pattern to cut-extrude into each wall of the box. My first attempt at this lattice design failed, but I learned about how to use offset commands to add thickness to lines for use in extrusions and how to think about negative space.

lattice fail

Sketch of lattice and extruding attempt

Too many fickle lines so I started over, this time making sure to use a simple polygon shape that I ensured was closed + rectangular patterning feature. I extruded just one part of this partern then rectangularly patterned the feature so that it covered the entirety of one of the surfaces. I then mirrored that onto each other surface, making use of offset planes to mirror to diagonal faces.

Next, I created a top to the box (since the shelling feature left the top open). Then I designed the inside pole to have lettering "FAB!" and some star symbols incorporated.

Timeline of design in Fusion

Once I completed the design, I exported it as an STEP file to be imported into Prusa Slicer. At its designed scale, the print would have taken 20+ hours! So I used the scale tool within Prusa which allowed me to easily shrink the box down to a more reasonable time.

slicebox pic

Viewing different layers of the print using PrusaSlicer's slicing tool. I decided to print on the i3MK3S with 0.8mm nozzle.

From the test prints, I anticipated this would be poorer in quality but faster. I set the supports at "support on build plate only" and infill at "10%". Will also advised in the future chamfering interior corners helps create supports built into the model.

After printing with the i3MK3S (in blue), Will printed another at a larger scale on the PRUSA MINI with 0.6mm nozzle (in green) and one on the PRUSA MINI with the 0.4mm nozzle (in pink). The one in green printed at much better quality and you can see the "FAB!" lettering inside if you look closely. The one in pink got completely messed up and was a fail!

3D Scanning

For 3D scanning, I downloaded the app RealityScan. Upon downloading, the apps provide these tips:

Avoid scanning clear, shiny, or plain objects
Objects that are detailed, food, or from nature are good for scanning
Use camera control mode to have full control of camera settings and to get highest image quality
Use Auto Object Masking to remove background
Augmented Reality Mode allows for auto capture from all angles

To begin, I wanted to scan a ring I have -- it's shiny so I'm breaking the rules but was curious to see what would result. I set up the ring on some white paper on a stable surface that I could rotate by hand while keeping the phone camera consistent. I changed the scanning mode to "Standard Mode" in settings, clicked the manual focus icon, turned on the torch light feature, and the focus peaking feature on. And began with 50 photos around 360 degrees of the ring.

Next, the app analyzed the images to generate a point cloud. I was surprised to see how well it went. After processing, I noticed the final result looked good but had some random extra filling in sections. I decided to redo that scan, taking much more care, time, and over 4 times as many pictures (~50 on first try, ~230 on second try). Despite my effort, the next 3D model came out worse!

ring reality scan ring reality scan 2

I decided to go through the process as if I was going to 3D print anyways. I downloaded blender since the RealityScan app exports the 3D model as an glb file and blender can import glb files and export as STL files which I would need to upload into Prusa Slicer. Since it was my first time using Blender, I played around with some of the features to try and smooth out the model.

shrink blender

Then I uploaded the STL file into the Prusa Slicer. Lots of error messages came up but I was impressed by Prusa Slicer's capabilities at detecting and correcting errors within the software. I used the fix by Windows Repair Algorithm feature which automatically fixes issues with the 3D models. Even after this, the model came out a mess! Wouldn't ever print it but cool to see the process.

ring prusa 1 ring prusa 2

Ring model on Prusa Slicer

After going through the process, I worked on a few more scans. This time I used an outdoor set up of white boards to start.

scan setup

Initial outside setup for 3D scanning. Eventually I just took one board and placed it on a stool.

Eventually I learned, that I liked using the Standard Mode scanning mode, which works best when I keep the camera in the same place and turn the board with the object on it. This got me much better results with the generated point cloud.

bread reality scan stick reality scan shore reality scan