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 3D printed a (very preliminary) mini smart speaker that requires no assembly.

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 assignments:
- 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 are guidelines that help us design 3D models that take into account the limitations of 3D printers, as well as maximise the quality and efficiency of the prints.

My Learnings from the Groupwork
I got to try 3 different 3D printers for the 1st time, and scrutinizing 3 different results gave me some understanding of the range of speed and quality of different machines. I also understood the limitations of each printers, and therefore the specific design considerations for each, such as wall thickness, bridge length, overhang angles, etc.

I also learned the key parameters that need to be considered when printing; such as supports, infill, etc., and that sometimes its about achieving an acceptable balance between quality and time/material use.

Follow this link for the Group documentation.

👉Major 3D Printing Technologies:

FDMSTLSLSInkjetPoly-jet

• Stands for “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, thus suitable for larger, functional parts.

• Stands for Stereolithography. Also called “Resin Printing”.
• World’s first 3D printing technology, invented in the 1980s.
• Liquid resin is hardened layer by layer by a light source. (light source: laser, digtal light projection or LEDs)
• Produces higher dimensional accuracy, smoother surface finishes, thus tighter tolerances.
• Also 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.

• Stands for “Selective laser sintering”.
• Most common method for industrial uses. (due to 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 higher-volume production through nesting.
• Often uses nylon: lightweight, strong, flexible, and stable against impact/chemicals/heat/UV light/water/dirt.

• Also called “binder jetting” of “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.

• Utilizes a unique inkjet-like process.
• Creates highly detailed and accurate models using liquid photopolymers.
• Able to produce multi-material and multi-color parts.
• Also able to achieve exceptionally smooth and detailed surfaces.

👉Common 3D printing filaments for FDM printers:”

PLAABSTPU

• Stands for “Polylactic Acid”.
• Biodegradable thermoplastic.
• Known for being easy to print with. (requires lower temperatures and produces less warping than other materials.)

• Stands for “Acrylonitrile Butadiene Styrene”.
• Recyclable plastic that offers good strength, durability, and heat resistance.
• Can be more challenging to print than PLA. (potentially requiring a heated bed and producing more fumes.)

• Stands for “Thermoplastic Polyurethane”
• Produces strong, flexible, rubber-like finish.
• It can stretch more than 5x its original shape before failing.
• While offering many useful properties, can be tricky to print.

Design and 3D print a small object:

Our 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 tips & techniques for 3D-printing successfully.
I am so 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 3D CAD model, 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 learn about 3D printing, I set myself only two design requirements, which were 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;

Export the model as a 3D file such as STL.

3D Printing Workflow

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

1. Slicing the 3D model to generate “G-Code”

First, we use a slicer software to convert our 3D model into a machine language which the 3D printer can understand, called G-Code.

👉A slicer takes a 3D file and generates G-code, which dictates the path (or “toolpath”) and speed of the 3D printer head. It also allows us to specify print parameters such as layer height, supports, etc and reflects them in the toolpath.

Since I decided to print with Creality K1C, I used the Creality Slicer.

These are the key parameters we should usually consider when slicing.

Parameter	Description	My setting
Printing Temperature	Consists of 1. extruder temp and 2. build plate temp. The 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 setting above parameters, press “Start Slicing”, and the slicer will create a preview where you can investigate each layer of print by moving the levers. You can also check the estimated print time. 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 very important to prevent build up of dirt. After printing, always rub the machine bed clean with alcohol.

Future of 3D Printing

Our visiting intern from MIT, Sophia gave us a mini lecture on interesting R&D activities around 3D Printing, such as new methods that print under water using light, or that attempt to fabricate in outer space, or new applications around fabrication of Spaceships, Buildings, Soft Robotics, etc.

Through this I gained some insight into some of the inherent limitations of 3D printers, such as the need for frames, its porous structure, etc, and the latest approaches and progress in overcoming them. It made me understand that 3D printers is still a developing field, and the importance of seeing it as a technology with so much potential still to be uncovered.

Results and Reflections

About 3D printing:
This week was a full week, packed with learnings about tips and tricks for making the best use of 3D printers.
This included knowing its specific advantages against other fabrication methods (such as the ability to print already assembled structures), awareness of the key “Design Rules”, understanding the traits of specific machines, and understanding how to balance various parameters for optimal results, etc.

After gaining some insight into the amount of practice and know-how required for successful 3D printing, I realised that it’s important to not get failures discourage me from the machine, but rather to make and experiment as much as possible, embracing a playful mindset, so that I can build-up expertise.

About CAD modelling:
I also gained more understanding about 3D CAD this week, including the importance of Parametric design. If I set up the parameters properly, I should be able to tweak the design easily just by changing the measurements. But I couldn’t set it up right, and ended up spending a lot of time recreating the model multiple times until some of the 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.

3D Scanning:

The 2nd part of this week’s assignment was about learning to digitize physical objects through 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: LiDAR scanner calculates the depth and proximity of the object’s surface to evaluate texture. Example is SENSE 2 3D Scanner (by 3DSystems)
  

These are the 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 does not have a Lidar sensor.

My initial plan for this exercise was to scan my wooden chair so I can start considering the bag-holder and coat hanger extention to model in the CNC week (Week 7). Unfortunately due to circumstances I was not able to carry the chair😢
So during the local session we took turns using the Revopoint Miraco scanner to try and digitize ourselves.

Scanning:

We placed a chair on a turn-table so that each of us could rotate 360 degrees while being scanned. We experimented with different environments and tools to find the conditions for achieving a good scan.

Processing & Finalizing model:

To be able to 3D print the data, we need to retouch it.
We transferred the scan to the Revo Scan 5 software. The “Quick retouch” feature helped close the gaps not captured during scanning. This file can be exprted as an STL file for 3D printing.

Reflections for 3D Scanning

Although there’s been lots of improvements in 3D scanning in recent years, we still found limitations with it, especially with surfaces that are dark, shiny, reflective, or transparent. Also, once the scanner losed focus, the scanner tended to lose orientation and create distorted results.

Through trial and error we did find some effective workarounds for enhancing the scan such as;
- Making sure the room is well-lit
- Understanding the scanner’s optimum distance and trying our best to not deter from that range.
- Having a contrasting backdrop

Useful links:

• Useful documentation

Design files:

• 3D CAD Model (DXF File)

Assignment Checklist:

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