3D PRINTING

3D-PRINTING

HI!! Welcome back to my blog! This week, I had recapped and built-on on my knowledge from CP5065, ICHE - 3D Printing! 😮 I had even 3D Print my design which I had made in CAD.

Why is learning 3D-Printing important?

3D-Printing enable one to quickly make what we need, when we need. It is also fully customizable to individual needs. It is becoming an important enabling technology in many chemical engineering fields as it is good for prototyping and good for end use parts as well. 

Prototyping	End Use Parts
Physical evaluation of the design	Extend lifespan of older equipment by printing obsolete parts
Perform functional testing before committing to full production run	Reverse engineer spare parts
Print numerous design iterations to identify and remove errors before production.	Customizable high vale/low volume End-Use production

What is 3D-Printing?

3D-Printing is described as Additive Manufacturing. Additive Manufacturing refers to objects built by adding layer-upon-layer of material. The material used can be any type of material, such as plastic, metal or even water soluble materials (will be explained more about it later) such as PVA.

Once a CAD sketch is done, the 3D-Printer reads in data from the GCode file, made using a slicer software and lays downs or adds successive layers of liquid, powder, sheet material or other, in a layer-upon -layer fashion to fabricate a 3D object. (AM Basics, n.d.) 

A slicer is a software that slices our CAD drawing into different layers, and this layers will be made so thin that it can be read/ represented as X, Y, Z coordinates information. This will give an output, GCode file, 

3 Types of 3D-Printing Technology

The 3 types of 3D-Printing are

1. FDM
2. SLA
3. SLS

FDM

FDM, also known as Fused Deposition Modeling, or Fused Filament Fabrication (FFF), is the most widely used form of 3D-Printing at the consumer level (hobbyist 3D printers). FDM 3D printers build parts by melting and extruding thermoplastic filament, which a printer nozzle deposits layer by layer in the build area.

FDM works with a range of standard thermoplastics such as ABS, PLA, and their various blends.

Advantages	Disadvantages
Quick	Tend to have visible layer lines
Low-cost prototyping of simple parts	Shows inaccuracies around complex features

FDM is not the best option for printing complex designs or parts with intricate features. Higher quality finished may be obtained through chemical and mechanical polishing processes. However, if we are only using it to print prototypes, or something simple, FDM is a good choice.

SLA

SLA which stands for Stereolithography was the first world's first 3D printing technology, invented in the 1980s. SLA resin 3D printers use a laser to cure liquid resin into hardened plastic in a process called photopolymerization.

SLA has the clearest details  and the smoothest surface finish of all plastic 3D printing technologies. However, the main benefit of SLA lies in versatility. SLA photopolymer resin formulations were created to have a wide range of optical, mechanical, and thermal properties to match those of standard, engineering, and industrial thermoplastics.

Advantages	Disadvantages
Tight tolerances	Parts are affected by moisture, heat and chemicals
Smooth surfaces	Limited to photosensitive resin
Minimal visible layer lines	-

SLA parts have sharp edges, a smooth surface finish, and minimal visible layer line. SLA is a great option for highly detailed prototypes requiring tight tolerance and smooth surfaces, and is widely used in a range of industries.

SLS

Lastly, SLS which stands for Selective Laser Sintering, is the most common additive manufacturing technology for industrial applicators. 

SLS printers use a high-powered laser to fuse small particles of polymer powder. The unfused powder supports the part during printing and eliminates the need for dedicated support structures. This makes SLS ideal for complex geometries, including interior features, undercuts, thin walls and negative features.

Advantages	Disadvantages
Excellent mechanical characteristics with strength resembling that of injection-molded parts	Slightly rough surface finish
Almost no visible lines	-

The most common material for selective laser sintering is nylon, which is a popular engineering thermoplastic with excellent mechanical properties. Nylon is;

• lightweight
• strong and flexible
• stable against impact
• stable against chemicals
• stable against heat
• stable against UV light
• stable against water
• stable against dirt

The combination of low cost, high productivity and establish materials make SLS a popular choice among engineers for functional prototyping and a cost effective alternative to injection molding.

Conclusion

FDM	SLA	SLS
Lowest Resolution	Highest Resolution	High Resolution
Lowest Accuracy	Highest Accuracy	Highest Accuracy
Worst Surface Finish	Best Surface Finish	Best Surface Finish
Worst Throughput	Good Throughput	Best throughput
Easy to use	Easy to use	Not as easy to use

Slicer Settings

Slicer settings are important as every 3D printer is different, every material is different, and every 3D model is different. Slicer settings will affect the product properties. Thus, choosing the correct slicer setting is important. Some important settings are, Temperature, Layer Height, Retraction, Supports, Infill and Shell Thickness.

Temperature

The temperature of the nozzle is the most important setting in slicer because without a perfect level of heat, no print will work. Nozzle temperature should be tune when we begin printing with a new filament. Different filament will have different melting point.  We can check the temperature by printing a temperature tower to see which values work.

Too high a nozzle temperature will case over-extrusion with blobs and zits all over the print.

Too low a nozzle temperature will cause under-extrusion, where not all the layers are fully printed.

Temperature Tower

For the bed temperature, generally, a hotter bed will provide a better adhesion, while a cooler one could lead to warping.

Some methods we can do to improve adhesion is using Skirts, Brims and Rafts.

Skirts are used to provide an outline - no adhesion

Brims allow some adhesion to the print perimeter

Rafts are full platforms on which the 3D print is places. Print adhesion is onto the bed raft instead of the bed.

Layer Height

Layer height is important as it affects the printing time, detail and part strength.

A smaller layer height will have more layers to the overall print. This means that the printer have more room to generate finite detail on parts but take a longer printing time and have a weaker part strength.

A bigger layer height is the opposite of a small layer height.

Retraction

Retraction determines how fast filament is sucked back into the nozzle to prevent material from oozing out when it is not being extruded. Retractions affects how the overall print looks as it may have strings, hairs or whisps.

Supports

Supports are structures that holds up overhanging features on models. Without supports, our printing will go haywire. Supports are printed out together with the product. They are usually very thin so that we can snip them off once the final product have been printed. There is also another way to print support. If our 3D printer has 2 nozzle, one of the nozzle can be used to print water soluble materials.

Water soluble materials such as PVA are use as supports. When our product has been printed, we can dunk our product into water for awhile. PVA being water soluble, will dissolve away. This allow our product to be cleaner as we do not need to snip off any excess parts.

Infill

Infill is the internal filling in the 3D printed parts. Infill allows us to better control the strength, weight, material consumption, and internal structure of a part without having to adjust its appearance or external features.

In the slicer settings, infill can be controlled using infill density and infill pattern.

More robust infill patterns and larger infill densities will extend printing times and consume more materials but will help to increase a part's strength and weight. There are many infill patterns, with its own design and characteristics, like concentric (for flexible parts), cubic (strong), and lines (fast). The infill density can be set to achieve our desired mix of printing strength, material consumption, and printing time. 

Shell Thickness

Lastly, shell thickness represents the number of lines in the walls of our prints. Infill are inside of the print while the shell is outside of the print. This means that they are completely solid and printed concentrically.

Shell thickness is an important setting to tune because it can significantly impact the strength of our model. The higher the shell thickness, the stronger parts will be and the longer it will take to print.

Now, I will document my CAD for my 3D printing design!

I have chosen to create a Box with Hinge! 

Documentation of Box with a Hinge

Step 1: To create our hinge, we will first create a box. 

 

Go to Create > Box > Choose the “X” and “Y” plane, and enter a dimension of 50mm by 50mm by 50mm.

Step 2: Sketch Box and Hinge

Firstly, go to Create Sketch, and select the Front face of the box. 

Next, go to Create and select “Line”. In the sketch palette, choose the Construction line.

Thirdly, create the line at the midpoint of the Box, at 25mm, and draw out the construction line. Length of line does not matter. This will be where we will be drawing 3 concentric circles.

Fourthly, draw the 3 concentric circles. Remember to deselect the construction line option. The dimensions of the circle are not important.

Fifthly, we will now specify the dimensions of the 3 circles.

The diameter of the innermost circle which is the pin, will be 3mm.

The gap between the innermost circle and middle circle will be 0.2mm.

The gap between the middle circle and the outermost circle is 3mm. 

Select the edge of the box, and the middle of the innermost circle, and enter a dimension of 5mm.

Sixthly, we will need to draw a line between the edge of the box and outside circumference of the outermost circle in order to close the sketch.

Next, go to Create > Line, and draw a small line between the midpoint of the box and the outside of the outermost circle (Knuckle). Ensure that the angle of the line is less than or equals to 45° so that we do not break the 45° rule. 

Repeat the step for the other side of the circle. 

Lastly, finish sketch.

Now, we will make a midplane, so that we can split our box into “Top Half” and “Bottom Half”.

Go to construct > Midplane.

Choose the Top of the Box, and the Bottom of the Box. 

To split our box into 2 halves, click Modify > Split Body > Click on our Box.

When the Split Body tab comes out, select the Splitting Tool and choose the middle plane. 

We now have 2 bodies, and we can rename them to “Top” and “Bottom”

Step 3: Extruding Hinge

Go to Create > Extrude > Select the 4 sketch features 

Extrude the hinge to -9.5mm and ensure that the operation is “Join”.

I have click on the eye icon for the Top body for better visualisation. 

At the side of the screen, click on the eye icon to have our sketch visible again. 

Now, I am going to create the wing a…

Go to Create > Extrude > Select the same 4 Profiles.

On the Extrude Dialog, go to Start > Click on the drop down > Choose Object.

For the Object, select the opposite face of the box and enter a dimension of 9.5mm.

Next, to do our pin, press our keyboard letter “e” to open the extrude dialog. 

Choose the centre circle in the sketch.

On the extrude dialog, change the “Extent Type” to “To Object”.

For the Object, choose the opposite face of the box.

Change the operation from Cut to Join.

Next, we will create the Knuckle for the top half of the box.

Turn off visibility for the bottom and turn on visibility for the top.

Again, type “e” on our keyboard so that the “Extrude” tab will appear.

Select the 4 features as shown.

On the Extrude dialog, change the direction from “Profile Plane” to “Offset”.

Set Offset to -10mm.

Set Distance to -30mm.

When turned on both the Top and Bottom body, this should be the product.

Step 4: Section Analysis

Under Inspect, click on Section Analysis.

Click on this face.

We can drag back and forth to check if the box is hollow.

Do another Section Analysis for the other side of the face.

Step 5: Making our Box Hollow

At the bottom left of our screen, it shows our timeline. Grab the vertical handle and drag it between the box command, and the sketch command. 

Go to Modify > Shell > Select all 6 faces > Key in an inside thickness of 3mm.

Back to the timeline, drag the vertical handle back to the end of the timeline. 

Step 6: Adding Snap Fit Parts

Back to Section Analysis, choose this section of the box, and turn off the top body visibility.

Next, go to Create Sketch and choose the inside face of the bottom body.

Go to Create > 2 Point Rectangle with dimensions 2 mm by 6 mm.

Use the constraint “Midpoint” to centre the sketch of the rectangle. Select the top edge of the sketched rectangle, and the top edge of the body. 

Press the letter “e” on our keyboard to bring out the Extrude dialog. 

Choose the rectangle sketch and give it a dimension or -2mm.

Set Taper Angle to -45°.

Go to Modify > Chamfer > Choose the top edge > enter dimension of 0.5 mm

Now, we will be doing the same to the Top body.

Turn off the bottom body view.

Turn on the top body view.

Turn on the Sketch for the 2-point rectangle.

Press the keyboard letter “e” again to bring out the extrude dialog.

Select the 2-point rectangle, and extrude out 2 mm.

Ensure that the Operation is set to “New Body”.

Go to Modify > Draft

For the Pull Direction, select the face towards the centre of the box.

For the Faces, select the top of our new body and grab the rotation handle to 60°.

Now, we need to combine the Top and Bottom bodies. 

Select Modify > Combine

For the target body, choose the top of the box.

For the tool body, choose the snap fit part.

Verify the operation is set to join. 

Now, we will need to create the catch point for the top of our box. 

Again, press the keyboard letter “e”, and choose our 2-point rectangle again. 

Enter a distance of 0.2 mm, verify the operation is set to cut.

Press the keyboard letter “e”, select the 2-point rectangle.

For start, click on the drop down and select “Object”.

For the object, choose the front face of the snap fit part and give it a -2 mm dimension, and a taper angle of -45°.

Let's add a fillet to our catch point to ensure a smooth operation.

Press the keyboard letter “f” and select the sharp point. Give it a 0.3 mm fillet.

We can use the Section Analysis to check for our extrusion. 

Step 7: 3D Printing

We will now animate the rotation of the lid. 

Go to Assemble > New Component > Click on the “From Bodies” checkbox > Select the Top and Bottom bodies. 

2 new components will be added in the browser tree; one for top and one for bottom.

 

Go to Assemble > Joint > Turn on the Section Analysis > select the centre of the Knuckle for component 1 > select the pin for component 2

The box is now able to rotate. 

Set angle to 180° so that it will be easier to 3D Print.

Step 8: Exporting to .STL file

Under File > Export > Change type to .STL file.

Embeded File:

Step 9: Import into Cura

In the Cura App, as our model is upside down, we can rotate it in Cura.

Click on the file, and select our .STL file.

This is the link for the .STL file:

https://drive.google.com/file/d/1TsVqDRMwylD5_BuX6311uB7tD9K5SwOQ/view?usp=sharing

Next, click on the “Lay Flat” option.

Then, click onto the icon beside it and click on the back of the Box to make it lay properly.

This will be how it looks.

3D Printer Machine Settings and Machine SOP:

Settings:

Nozzle Size: 0.4mm

Standard Quality (Layer Height): 0.2mm

Infill: 20%

No Support and Bed Adhesion needed.

• As the box and the hinge are connected closely, thus the bridge is very short, supports are not needed. The box is also square, and is laid on the bed. Moreover, I had followed the 45° angle rule, thus no support is needed although the hinge is slanted.

Machine SOP:

1. Save model into thumbdrive

2. Click Prepare

3. Preheat PLA

4. Wait until Nozzle is at desired temperature. (200℃ for mine)

5. Select Disable Stepper

6. Move X: 0
   Move Y: 0
   Move Z: 25

7. Select Disable Stepper

8. Click Print

9. Let the fully printed product cool down to around 40℃ so that it can be removed from the bed easily.

Why it cannot be made subtractively?

Subtractive Manufacturing is a process by which 3D objects are constructed by successively cutting material away from a solid block of material.

Subtractive manufacturing can be done by manually cutting the material.

Additive Manufacturing refers to objects built by adding layer-upon-layer of material.

My Model: a box with hinges

The cross section of a hinge consists of Knuckles and Pin.

As the pin is inside the Knuckles, it is very hard for it to be made by removal of materials. Thus, a hinge can only be made by the addition of material, additive manufacturing.

Process of 3D Printing:

Printed Object:

Reflection:

The process for 3D Printing includes the CAD of our design, changing it into an .STL file, then getting a GCode before we can send it to the 3D Printer machine for our design to be printed. In the lesson taught, I was recapped on 3D printing. In this practical, I was taught how to use the 3D Printer machine.

3D Printing is important as it enables one to quickly make what we need, when we need. It is also fully customizable to individual needs. It is becoming an important enabling technology in many chemical engineering fields as it is good for prototyping and good for end use parts as well. 

My original idea of making a 3D Printed chess piece was not able to be done as it can be made subtractively, such as the carving method. Thus, it did not meet the criteria and I had to redo my CAD to a design which cannot be made subtractively. Therefore, I had chosen to do a Box with Hinge as the hinge can only be made additively.

Being able to see my CAD design being brought to “life” was very interesting. I always had the thought that a 3D Printer machine will be very difficult to use as it is a very futuristic machine. However, after going through 1 lesson and the practical session, I realized that it was indeed actually quite easy to operate as all we needed was to CAD our design and then operate the 3D Printer machine with just a few steps.

As my group is doing a CO system device for our CPDD project, we will need to make a casing for the components, Arduino Board, Breadboard and Dupont Wires. We have decided to 3D print our design. Now, having gone through the lesson and practical on 3D Printing, I feel confident and competent to 3D Print our required casing. 

As I mentioned, I used to think that 3D Printing would be very difficult and tedious to learn. Now, I think that 3D Printing is indeed easy, and fun to use. This has taught me that nothing is difficult as long as we have the heart to learn. So, next I will look forward to learning more interesting topics taught in CPDD module, which can potentially help me develop my skill for the CO system device, or even in the long run when I am working in future.

Documentation for Original Design (Chess Piece):

For this CAD, I had learnt a new skill from my own researching through YouTube, and it may look like a cheating method. 😅

Step 1: Finding for Suitable Image

Using a reference picture found on google, I will import this picture into Fusion360.

Step 2: Inserting our Image into Fusion360

To import our image into Fusion360, simply go to "Insert" and select "Image". 

This interface will then appear, and we shall click on "Insert from my computer", located on the bottom left of the screen.

It will then ask which face do we want to place the picture on. We can choose any face, but I had gone for the front view.

Step 3: Sizing the Image for Outlining

As a standard King chess piece has a height of 95mm, I will scale my 3D design to have the same dimensions. Thus, I will need to scale my image size to fit the dimension I am going for.

Firstly, click on the drop down for our "Canvase". 

Secondly, right click on the drop downed "Chess Pieces" and click on "Calibrate"

Thirdly, we will place two points, one at the top of the chess piece, and one on the bottom of the chess piece. We will then give it a dimension of 95mm.

Our chess piece is now calibrated!

Step 4: Creating Sketch

We will now create the sketch of our design. 

Click on "Create Sketch" located on the top left corner of the screen, and click on the plane given.

Step 5: Outlining the King Image

As our chess piece is symmetrical, all we need to do, is to outline only half the image!

Firstly, draw a line in the middle of the image. This will be the symmetrical line.

We will be outlining our image using the "Lines" and "Arc" option, specifically the "3-Point Arc"

Secondly, using the symmetrical line's bottom point, we will start outlining the shape of the King using lines and arcs.

However, keeping the 3D printing 45° rule, our arc is more than 45°. Our design will need to use supports if we do not change. As I do not want to print our any supports, I will change the angle of the arc.

I had reposition the arc such that it will be less then 45°. My design does not have to be 100% accurate to the image, therefore cutting a bit of the image will not matter.

Continue to outline the image and this will be the end result!

We can now click on "Finish Sketch"

Step 6: Making our Sketch 3D

By clicking on the "eye" icon of our "chess pieces" image, we will turn the image off and we can see our outline. 

Next, we will click on "Revolve".

This interface will appear.

This are the parameters which I had filled in.

Profile: Profile of our Image

Axis: Centre Axis

Angle: 360

Direction: One Side

Operation: New Component

With the parameter entered, this is the final outcome!

Step 7: Adding of Material to the King (Optional)

On our keyboard, click on "a" and the "Appearance" tab will come out.

Click on "Library" or scroll down to choose the material we would like to apply to our product.

In my case, I will be choosing Plastic- ABS (white).

Click and drag the material to our design.

We can change the colour of the material by editing. Right click on our material used and click on "Edit".

We can change the colour to any colour we want. I had chosen black.

This is the final outcome!

Step 8: Outlining the Queen Image

This will be the same as step 5. 

Firstly, draw the symmetrical line.

Secondly, trace the outline of the image using Lines and 3-Point Arcs.

Step 9: Making our Sketch 3D

This is also the same as step 6.

We will use the "Revolve" tool on our Queen.

Step 10: Adding of Materials to the Queen (Optional)

Repeat step for Step 7.

Lastly, these are our 3D design!

Step 11: Export to STL file

If we only have 1 product to export, we can go to "Files", then "Export" and save to ".STL file".

However, since I have 2 products, I have to save each one as its own .STL file.

On the left hand side of the screen, right click on the product and select "Save as mesh".

This tab will appear. Change format to "STL (binary)" and the rest stays at default and we are done! 

Repeat the same step for the Queen.

Embed CAD 3D Design

References:

• Additivemanufacturing.com. n.d. AM Basics. [online] Available at: <https://additivemanufacturing.com/basics/> [Accessed 15 December 2021].
• Chessbazaar.com. n.d. Minimalist Hermann Ohme Chess Pieces in Dyed Boxwood & Box Wood - 3.75. [online] Available at: <https://www.chessbazaar.com/offers-zone/99store/minimalist-hermann-ohme-chess-set-in-dyed-boxwood-box-wood-3-74-king.html> [Accessed 16 December 2021].
• Formlabs. n.d. 3D Printing Technology Comparison: FDM vs. SLA vs. SLS. [online] Available at: <https://formlabs.com/asia/blog/fdm-vs-sla-vs-sls-how-to-choose-the-right-3d-printing-technology/> [Accessed 15 December 2021].
• O'Connell, J., 2021. [online] Available at: <https://all3dp.com/2/3d-slicer-settings-3d-printer/> [Accessed 15 December 2021].