5. Print and Scan 3D Objects

This week we learnt all about 3D Printers. When is adopting 3D printing the smart choice over other methods? What are its limitations and difficulties, and what are the best practices for getting good quality prints? These were the 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 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” for the 3D printers at FabLab Kamakura. Follow this link for the Group documentation.

My Learnings
Through this week’s groupwork, I learnt the key considerations when designing for 3D printing. The exercise of scrutinizing the print characteristics of 3 different printers gave us good understanding of how different specs affect printing speed and quality. 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.

3D printing:

The 2nd assignment of this week was to “Print a small object that could not be easily made subtractively”. This is the object I managed to finally print, after many (five, to be exact) failed attempts!

Although facing so many repeated failures really tested my limits this week, every failed attempt ended up teaching me something important about 3D printing. I am particularly thankful for FabLab Kamakura’s 3D printer guru Yamamoto-san for staying by my side and helping me get over every setback!

Designing for 3D Printing

Initial Research

Before designing my CAD model to print, first I needed to understand the assignment requirements by figuring out the difference between “Additive” and “Subtractive” manufacturing methods, and what constitutes 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)

CAD Design

Design Concept:
Based on the above research, I decided to attempt to prototype a small smart-speaker interface to be used in the kitchen. I wanted something that could hang from kitchen rails, so that it could be situated relatively close to the chef’s face level, for easy hands-free operation.

Inspiration:
Incorporating [Animals]https://www.dusklights.co.uk/fitting-style-c93/animals-c442?pp=0 to make the object more endearing.

CAD modelling process:
I initially made these 3 structures, consisting of overhang/undercut elements, but my instructor pointed out that it could potentially be made by a sophisticated robot arm. So I decided to assemble the 3 structures to make it a 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

I learnt that there are a number of key considerations in each steps of the 3D printing process to ensure a successful print.

1. Slicing

The 3D model needs to be first converted into a machine language which the 3D printer can understand, called G-Code, by using slicer software. Since I decided on Creality K1C as my 3D printer this time, I used the Creality Slicer.

On the Slicer software, I set these print setttings:

Parameter	Description	My setting
Printing Temperature	Consists of 1. extruder temp and 2. build plate temp. Varies depending on material. Extruder temperature for plastic filament 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 with corners/edges	None
Raft	Also good for increasing bed adhesion, particularly with objects with small contact with plate. Also Good for clean first layer of model	Initially none, but added for the final successful print
Support	Needed when design has an overhang above 45 degree	Initially none, but added after 1st fail
Layer height,mm	Affects print resolution, details and surface smoothness. 0.2 will be the most commonly used setting for printing at the Fab Lab	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. Based on this, you could go back to the settings and tweak it 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, 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 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. 3-D 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 printing until 1st layer is successfully printed.
If printing fails for any reason, abort the printing, investigate issues and try again.

4. Post-Print Processing & Maintenance

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.
After printing, always rub the bed clean with alcohol after use, for the next person using it.

Future of 3D Printing

Our visiting intern from MIT, Sophia shared with us some interesting R&D activities around 3D Printing, with applications in Space exploration, Buildings, Robotics, etc.

Results and Reflections

xxxxx Update needed

This week I understood of the various knowledge, techniques and mindsets for utilizing the 3D printer to its maximum potential. This includes knowing its forte, awareness of the Design Rules, understanding the characteristic of the specific model, understanding how to balance various parameters for optimal results, etc, etc.
Despite many of the challenges I faced, I felt an immense satisfaction when I finally held my final perfect print. Looking to the future, I would like to be able to approach 3D printing with a curious, experimental mindset, as a creative tool with still lots of potential to discover

Another major lesson I learnt from this week is to adopt Parametric design as much as possible, so I can adjust the measurements according to the tolerance. Due to this oversight, I had to spend a lot of time editing the model, each time the printed hinge failed to rotate. Next time, I would allow for at least 0.5mm gap between narrow gaps, based on the ProtoLab’s Design Rule. (A challenge I stil face with CAD modelling on Fusion is being both pragmatic (such as designing parametrically) at the same time as being creative/explorative!)

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 does 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:

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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