5. Print and Scan 3D Objects

This week, I tried to learn all there is to know about 3D printers.
When is adopting 3D printing the smart choice over other fabrication methods? What are its limitations, and what are the best practices for achieving a good print? These were some of the important questions I could get more clarity on this week.

For my individual assignment, I attempted to prototype a (very preliminary) mini smart speaker for my final project.

I also learnt how to digitize physical objects through 3D scanning.

Assignments for this week (Feb 19-Feb 25):

Group assignment:

• Test the design rules for our lab’s 3D printer(s), and document it
  

Individual assignment:

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

Groupwork:

The goal of this week’s group assignment was to understand the “Design rules” when designing for 3D printing at FabLab Kamakura. These guidelines help us take into account the limitations of 3D printers, while maximising efficiency and quality of the prints.

My Learnings from the groupwork
Apart from getting first-hand understanding of the workflow for 3 different machines at FabLab Kamakura, scrutinizing 3 different results gave us good understanding of how different machine specs can potentially affect printing speed and quality. We also understood the limitations of each printers, and therefore the specific design considerations for each printers, such as wall thickness, bridge length, overhang angles, etc.

We also learned that there are lot of parameter tweaking we could do to ensure good quality prints while being mindful of resource (such as time, filaments) use.

Follow this link for the Group documentation.

👉Basic Information on 3D Printers

Different 3D Printing technologies:
FDM (Fused Deposition Modeling):
Common method that uses thermoplastic filaments which are molten and extruded through a tube layer by layer. Known for being budget-friendly, and suitable for larger, functional parts.
STL (Stereolithography), or Resin Printing:
World’s first 3D printing technology, invented in the 1980s. Liquid resin is hardened layer by layer by a light source (laser, digtal light projection or LEDs)
Produces higher dimensional accuracy, smoother surface finishes, and tighter tolerances, and allow much more diverse sets of material properties than other methods. Sometimes even used for creating actual end-use products and tools. Higher running cost than FDMs.
SLS (Selective laser sintering):
Most common method for industrial uses, for its ability to produce strong, functional parts. Uses a high-powered laser to fuse small particles of polymer powder. Ideal for complex geometries, as well as enabling higher-volume production through nesting. Often uses nylon, which is lightweight, strong, and flexible, as well as stable against impact/chemicals/heat/UV light/water/dirt.
Inkjet 3D printing / binder jetting / drop-on-powder printing:
Liquid binding agent is selectively jetted onto a powder bed to create 3D objects. Particularly useful for creating complex, multi-material parts with high resolution.
Poly jet:
Utilizes a unique inkjet-like process to create highly detailed and accurate models using liquid photopolymers. Able to produce multi-material and multi-color parts, as well as achieve exceptionally smooth and detailed surfaces.

Common 3D printing filaments for FDM printers:
PLA (Polylactic Acid):
Biodegradable thermoplastic. Known for being easy to print with, requiring lower temperatures and producing less warping than other materials.
ABS (Acrylonitrile Butadiene Styrene):
Recyclable plastic that offers good strength, durability, and heat resistance. It can be more challenging to print than PLA, potentially requiring a heated bed and producing more fumes
TPU (Thermoplastic Polyurethane):
Produces strong, flexible, rubber-like finish. It can stretch more than 5x its original shape before failing. While offering many useful properties, it can be tricky to 3D print.

Design and 3D print a small object:

The personal assignment for this week was to “Print a small object that could not be easily made subtractively“.
Although this may sound simple, successfully executing this task requires understanding of the unique advantages of “Additive” manufacturing methods over “Subtractive” methods, as well as what constitutes as “not easily made subtractively”.

I spent the first half of the week understanding these concepts and designing a model that convinced my instructors that it indeed was not easy to make if subtractively.

In the second half of the week, I battled with successfully printing the model that I designed, which was only achieved after 4 very different failures! These were the iterations I went through;

Despite the many setbacks I faced, when I finally held my final perfect print, I was overcome with an immense satisfaction!


Although facing this many repeated failures really tested my limits this week, every failure gave me important understanding about 3D printers, and about how to 3D-print successfully.
I am especially thankful for FabLab Kamakura’s 3D printer guru Yamamoto-san for staying by my side throughout, and helping me get over every setback!

Designing for 3D Printing

Initial Research

Before designing my CAD model to print, I needed to better understand the assignment requirements, by figuring out the difference between “Additive” and “Subtractive” manufacturing methods, and what constitute as “not easily made subtractively”.

[RESEARCH 1/3] What is Additive and Subtractive Manufacturing?
3D Printing is a type of “Additive manufacturing”, which is a process of adding materials layer by layer to form an object, rather than the subtractive method of cutting into a block of material.
During my research, I found that there are 3 main approaches to forming 3D objects;

1. Subtractive Manufacturing (Covered in Week 3 Laser cutting, Week 6 Milling, Week 7 CNC)
   
   
2. Additive Manufacturing (Covered this week)
   
   
3. Formative Manufacturing (Covered in Week 14 Molding and Casting)
   
   

[RESEARCH 2/3] Advantages & limitations of Additive manufacturing methods

In what situations is adopting 3D printing the smart choice over subtractive methods? These were my conclusions after some desk research.

Main advantages and disdvantages of 3D printers

◆ MAIN ADVANTAGES;

• Enables rapid prototyping and customisation
  You could make relatively sophisticated working prototypes and iterate/customise relatively easily by making use of 3D printer and CAD tools.
  
• Enables complex geometry and internal structures
  3D printers enables formation of complex objects which are also light-weight and make use of optimum material (which translates to reduced wastage).
  

◆ MAIN LIMITATIONS:

• Printing could quite easily fail (this can minimised by good understanding of Design Rules)
  
• Long printing time - Depending on material, size and printer, it could take hours to print (but speed is improving significantly in recent years)
  
• Technical knowledge required for printing well (There are a lot of parameters we could control such as speed, temperature, layer size, etc)
  
• Cost - Up front investment, and running cost of some of the more sophisticated materials
  
• Porous structure - especially if the printed structure will be used around food, the porosity can lead to bacterial growth, posing a health hazard. Applying food-safe coating can help, or avoid multiple use all together.

[RESEARCH 3/3] What is “not easily made subtractively”?
Answer: Something that has undercuts, overhangs (up to 45 degrees), nested parts, or print-in-place (that can’t be disassembled), etc.

What’s an undercut?

A feature that can make it difficult for a part to be ejected from the mold. It can be protrusions, holes, cavities, or recessed areas. (Reference: Protolabs)

What’s an overhang?

A section of a model that extends outward from the vertical axis without direct support. (Reference: AnkerMake)

What’s a print-in-place?

A design where a 3D model is created in a way that allows it to be printed entirely without needing any additional assembly or support structures. >(Reference: Instructables)

What’s nested parts?

Nesting means optimising your part orientation to minimise their combined volume expenditure. (Reference: Solid Print 3D)

My Design Concept

Based on the above research, I decided to prototype a small smart-speaker interface that could be used in the kitchen, making sure to include overhang/undercut elements.

Since the objective of this task was not to produce a perfect design, but to simply learn about 3D printing, I set myself only two design requirements, which was that it had a small pocket to contain a speaker device, and that it could hang from kitchen rails, close to the chef’s face level, for easy hands-free operation.

Design-wise, I also hoped to incorporate some kind of Animal to make the object more endearing.

3D CAD modelling

I initially modelled these 3 structures that consisted of overhang and undercut elements, but my instructors pointed out that this could still be potentially made by a sophisticated robot arm. So I decided to assemble the 3 structures into one “printed-in-place” object.

These are the steps I took to design my model. To get more CAD practice I followed this Fusion360 for beginner’s tutorial, customising it to look like a chef squirrel.

First, I created the hook holder component.

1. Create a circle and extrude
   
   

2. Add a slot, and add an ear at the top
   
   

3. Extrude the slot, mirror it, then delete the ears on 1 side by filleting.
   
   

4. Add a back support, and cut out the side
   
   

5. Add holes for the screw.
   
   

6. I tried to create a squirrel face, but couldn’t make a cute one so gave up :(
   
   

Next I made the hook component.

1. I made a circle and extruded, and added a rough sketch of the hook.
   
   

2. Added the constraints and dimensions for the hook
   
   

3. Filleted the corners.
   
   

4. Added handle components
   
   

5. And added a chef’s hat on top.
   
   

Finally, I made the screw;

3D Printing Workflow

Here I will outline the 3D printing process with key considerations.

1. Slicing to generate G-Code

First, the 3D model needs to be converted into a machine language which the 3D printer can understand, called G-Code, by using a slicer software. Since I decided to use Creality K1C, I used the Creality Slicer.

These are the key parameters that usually should be considered.

Parameter	Description	My setting
Printing Temperature	Consists of 1. extruder temp and 2. build plate temp. Optimum temperature depends on material. For plastic filaments, it is usually between 205-225.	The default value for PLA, 210˚C
Print speed	Depends on printer as well as quality requirements. To get more details, consider reducing speed.	Default value; 300mm/s for inner wall, 200mm/S for outer wall
Infill	Expressed as a percentage, ranging from 0–100%. Higher infill percentage results in a denser, stronger print, while a lower percentage makes the object lighter but potentially less durable	Value recommended by my instructors; 15%
Skirt	Good for purging nozzle before printing model	2 rounds
Brim	Good for increasing bed adhesion, particularly when there are corners/edges	None
Raft	Also good for increasing bed adhesion, particularly with objects with small contact with plate. Also Good for getting clean first layer	Initially none, but added for the final successful print
Support	Needed when design has an overhang of above 45 degree	Initially none, but added after 1st fail
Layer height	Affects print resolution, details and surface smoothness. 0.2 will be the most commonly used setting at FabLab	Experimented with 0.17 and 0.2 and settled on 0.2
Wall thickness	Value must be multiple the size of nozzle to avoid gaps	Default value

After inputting the settings and selecting “Start Slicing”, the slicer will create a preview where you can investigate each layer of print by adjusting levers. You can also check the estimated print time. Check the result and if necessary, go back to the settings to tweak the parameters to optimise the print.

2. Setting up Printer

Once you are satisfied with the settings, turn on the printer power supply, and prepare it for printing by following below steps.

2.1 Clean bed & nozzle end
Before starting heating, it’s a good idea to clean bed with alcohol and cloth, as oils and dirt can prevent the prints from sticking (you need to clean while it’s still cold as alcohol will evaporate when heated).
Also clean the nozzle end, to remove any remaining filament.

2.2 Load filament
Load the filament you desire, and select extrude to set it in place. With some printers, it may help to cut the end diagonally before loading.

2.3 Set bed level and Calibrate
You can skip this step with some printers, which has an automatic calibration feature (like the Creality printer I used).

3. 3D Print!

After above, we’re finally ready to start printing. Press Start print.
Since printing failure is not uncommon, it’s recommended to always observe the progress until 1st layer is successfully printed.
If printing fails for any reason, abort, investigate issues and try again.

4. Post-Print

If support was added, like in my case, remove the supports, using pliers if necessary. Also remove unnecessary threads and sand down some rough surfaces if necessary.
Regular maintenance of the machine is also important. After printing, always rub the machine bed clean with alcohol.

Future of 3D Printing

Our visiting intern from MIT, Sophia shared with us some interesting R&D activities around 3D Printing, such as new methods that use water and light, or that attempt to fabricate in outer space, or new applications in Spaceships, Buildings, Soft Robotics, etc. The lecture shed light on the limitations of 3D printers, such as the need for frames, its porous structure, etc, and the real-world ideas for overcoming these limitations.

Results and Reflections

This week was a full week, packed with many learnings about tips and tricks for making the best use of 3D printers.
This includes knowing its specific forte against other manufacturing methods, awareness of the key Design Rules, understanding the characteristic of each specific model, understanding how to balance various parameters for optimal results, etc.

I also learnt the value of adopting Parametric design as much as possible, which, when done well, can enable me to adjust the measurements easily when needing to tweak the design. I learnt through this the hard way as, because I had not designed parametrically, I had to spend a lot of time recreating the model multiple times until some gaps were wide enough for the printed hinge to rotate. (I later realised that 0.5mm gap was in fact already recommended as part of the ProtoLab’s Design Rules). It’s always a challenge to be both pragmatic (such as designing parametrically) as well as creative/explorative when CAD modelling, but it’s useful to be aware of the importance of switching these two different mindsets.

Now that I have some degree of understanding about the amount of practice and know-how required for successful 3D printing, I think it’s important to not get failures discourage me from the machine, but rather to embrace a playful mindset and to keep making and experimenting to build a good knowledge base. After all 3D printing is still an emerging technology with endless potential awaiting to be discovered!

3D Scanning:

The 2nd part of this week’s assignment was to learn how to digitize physical objects by 3D scanning.

2 major types of scanning technology;

• Photogrammetry: creation of 3D model from a photograph. E.g., Qlone, Trnio(iOS), AutoDesk ReCap Photo.
  
• LiDAR (Light Detection and Ranging) scanning: Scanner calculates the depth and proximity of the object’s surface to evaluate texture. Example is SENSE 2 3D Scanner (by 3DSystems)
  

3D scanners available at FabLab Kamakura:

Spec	Sense 2 (3D Systems)	Miraco (Revopoint)
Scanning Technology	LiDAR	Photometry? (Technology is not clearly explained, but apparently Uses innovative “quad-depth camera system”)
Scan volume	Min:20cm x 20cmx 20cm, Max: 2m x 2m x 2m	Min: 10 x 10 x 10 mm, Max: 4 x 4 x 4 m
Spatial X/Y resolution	0.5m: 0.9mm	Up to 0.05 mm
Depth resolution	0.5m: 1mm	Up to 0.02 mm
Operation range	0.2m - 1.6m	Closest:28 x 53 @ 100 mm, Farthest: 975 x 775 @ 1000 mm
Field of view	Horizontal: 45°, Vertical: 57.5°, Diagonal: 69°	unknown

I was also recommended the Scaniverse, phone App which uses LiDAR (Specs unclear) but unfortunately my iPhone SE did not have a Lidar sensor.

My initial plan for this exercise was to scan my wooden chair so I can consider the bag-holder and coat hanger extention to model in Week 7 using CNC. Unfortunately this plan was not realized because I could not bring my chair to FabLab Kamakura this week due to circumstances :(
During the local session we used the Miraco scanner to try and digitize ourselves.

Setting up

We placed a chair on a turn-table so that each of us could take turns being scanned.

Scanning

We experimented with different environments and tools to get a good scan.

Processing & Finalizing model

To be able to 3D print the data, we need to export it and retouch it.
We exported the STL file and retouched using the Revo Scan 5 software. The Quick retouch feature helped me close the gaps not captured during scanning and get it to a 3D printable format.

Reflections for 3D Scanning

We found out that despite huge improvements in 3D scanning in recent years, there are still limitations such as with;
- Objects that are dark, shiny, reflective, or transparent - Once the scanner loses focus, the scanner can lose orientation and create distorted results

We also found some effective ways to enhance the scan such as;
- Making sure the room is well-lit
- Understanding the scanner’s optimum distance and trying your best to not deter from that range.
- Have a contrasting backdrop

Useful links:

• Useful documentation

Design files:

• 3D CAD Model (DXF File)

Assignment Checklist:

• [ x ] Linked to the group assignment page
• [ x ] Explained what I learned from testing the 3D printers
• [ x ] Documented how I designed and 3D printed my object and explained why it could not be easily made subtractively
• [ x ] Documented how I scanned an object
• [ x ] Included my original design files for 3D printing
• [ x ] Included my shots