1. Test the design rules for your 3D printer(s)
   1. Design and 3D print an object (small, few cm3, limited by printer time) that could not be made subtractively
   2. 3D scan an object (and optionally print it)

Plan for  the week



3D Scanning and printing, an interesting week where we can fabricate our design and also 3D scan the real object. Back in Nepal, I used Upbox+ from tiertime for printing 3D objects using filaments like PLA, ABS and PETG. 3D printer, as the name suggests, is a printer, which prints a 3D object as per our 3D file. 3D printing is an additive manufacturing process where the physical object is created by adding material layer by layer from he digital file.



3D printing works layer by layer to form a shape. If you see the image below, differently trimmed paper layed one over another forms the shape for thumb cut in 3D. Similar to this, 3D printing also works on similar principal of adding layer by layer to form a complete physical 3D object.



As other digital manufacturing process, this also requires a digital file to operate. We should have a 3D file designed in any software in stl format. After we have the stl file we process it in a slicer which basically slices the 3D in different layers according to our input. A G-code then exported from the slicer to the printer which include printer settings and tool path based on which the 3D printer operates.



3D printers have a head which might be extruding plastic or pointing laser or UV or any depending upon the application of printer. They move that head in a 3 dimensional space for making the 3D product. We can categorize printer by mainly two ways. One is according to the technology and another kinematics or the mechanism behind the movement.

Types of 3D printing Technology

Based on the Technology used there are different types of printers. It can be differentiated by the difference in the process as follows.

  1. Material Extrusion
    - Fused Deposition Modeling (FDM) 
  2. Vat Polymerization
    - Stereolithography (SLA) 
    -Digital Light Processing (DLP)
    -Masked Stereolithography (MSLA) 
  3. Powder Bed Fusion
    - Selective Laser Sintering (SLS) 
    - Electron Beam Melting (EBM) 
  4. Material Jetting
    - PolyJet 3D printing 
    - Binder Jetting 
    - Metal Binder Jetting 
    - Sand Binder Jetting

I tried to differentiate it by following way.


Now, Let me explain about 3 types which are most commonly used.

Fused Deposition Modeling (FDM)

Fused Deposition Modeling printer is the most commonly available printer in the market. We will be using this type of printer in our Kochi lab to print our designs. The way it works is that a spool of filament is loaded into the 3D printer and fed through to a printer nozzle in the extrusion head. The printer nozzle is then heated to the desired temperature, and the extrusion motor pushes the filament through the heated nozzle, causing it to melt.The printer then moves the extrusion head along with specified coordinates, laying down the molten material onto the build plate where it cools down and solidifies. Once one layer is complete, the printer prints the another layer above the previous one and retpeating the addition of layer upon layer, the 3D object is printed.

They use Thermoplastic filament as the material. Most commonly used materials are

  • PLA
  • ABS
  • PET
  • PETG
  • TPU

Applications: Protyping, DIY, product design, Electrical housings; Form and fit testings; Jigs and fixtures; Investment casting patterns
Pros: Compararively cheap, Decent surface finish, Full color and multi-material available
Cons: Brittle, barely sustainable for functional parts, high print time




Stereolithography (SLA)

Stereolithography is the world’s first 3D printing technology which invented by Chuck Hull in 1986. Vat Polymerization is a 3D printing process where a light source selectively cures a photo-polymer resin in a vat (container). An SLA printer uses mirrors, known as galvanometers or galvos, with one positioned on the X-axis and another on the Y-axis. These galvos rapidly aim a laser beam across a vat of resin, selectively curing and solidifying a cross-section of the object inside this building area, building it up layer by layer. SLA printers excels at producing parts with high levels of detail, smooth surface finishes, and tight tolerances. The quality surface finishes on SLA parts, not only look nice, but can aid in the part’s function—testing the fit of an assembly, for example. It is widely used in medical field like dentistry. They use Photopolymer resin (Standard, Castable, Transparent, High Temperature) at the material.

Applications: Injection mold-like polymer prototypes; Jewelry (investment casting); Dental applications; Hearing aids
Pros: Smooth surface finish; Fine feature details
Cons: Time onsuming process, supports needed




Selective Laser Sintering (SLS)

Selective Laser Sintering process works on the sintering principle, which means heating the powder just below its melting temperature to fuse it. In SLS, a laser selectively sinters the particles of a polymer powder, fusing them together and building a part layer-by-layer. The materials used in SLS are thermoplastic polymers that come in a granular form. SLS 3D Printing is used for both prototyping of functional polymer components and for small production runs, as it offers a very high design freedom, high accuracy and produces parts with good and consistent mechanical properties, unlike FDM or SLA.
In SLA 3D printing, first, a bin of polymer powder is heated to a temperature just below the polymer’s melting point. Next, a recoating blade or wiper deposits a very thin layer of the powdered material — typically 0.1 mm thick — onto a build platform.Then a CO2 laser beam then begins to scan the surface. The laser will selectively sinter the powder and solidify a cross-section of the object. Just like SLA, the laser is focused on the correct location by a pair of galvos. When the entire cross-section is scanned, the build platform will move down one layer thickness in height. The recoating blade deposits a fresh layer of powder on top of the recently scanned layer, and the laser will sinter the next cross-section of the object onto the previously solidified cross-sections. These steps are repeated until all objects are entirely manufactured.




3D Printers Kinematics

Most common FDM printers use cartesian kinematics but there are other mechanisms as well on which head is moved. They are Cartesian, Delta, Polar and 3D printers with robotic arms. The Printer we are using, Ultimaker 2+ also is a FDM printer which uses Core XY, cartesian kinematics. To know more about the movement please follow this link

Click here to know more about different kinematics, their advantages and disadvantages.

Ultimaker 2+

We will be testing and using this printer for this week. Ultiaker is a FDM printer which works on Core XY movement. Thought filament size of 1.75mm is common among general FDM 3D printers, Ultimaker however requires filament of 2.85mm diameter. It has a print volume of 223 x 223 x 205 mm with a single extruder unit. It can print with followig materials.

  • PLA
  • ABS
  • CPE
  • CPE+
  • PC
  • Nylon
  • TPU 95A

You can download the manual  here to know more about the Ultimaker 2+

Slicing the model: pre-processing

In order to 3D print something, you need a slicer which is used to generate file which 3D printer understands. We will be using Ultimaker Cura as a slicing software. 3D printers normally have a dedicate slicer or they can use open source slicer as well. You can Download Ultimaker cura from this link. The basic things slicer does are following

  1. Load the model
  2. Resize, orient, duplicate the model ar per your requirement
  3. Input parameters like layer height, shell thickness, infill, material, print speed, support etc
  4. Slice it
  5. Save the output file (g-code) on a SD card
  6. Load the SD card in your printer and start the print.

Parameters for 3D printing

  1. Layer Height: Thickness of each layer, defines the resolution hence quality of print.
  2. Shell thickness: Boundary layer thickness, defines strength of outer shell
  3. Infill: Material inside the model, change in infill changes time, strength and material consumption.
  4. Material: Type of material, selects correct temperature of nozzle and bed for smooth print.
  5. Speed: Speed of the extrusion head movement, defines quality and accuracy of your print.
  6. Travel: Z axis retraction to prevent collision.
  7. Cooling: Turns on the fan accordingly to adjust rate of cooling of filament just after extrusion.
  8. Support: Structure for overhanging parts.
  9. Bed plate adhesion: Type of adhesion with the build plate.

You can get more knowledge about these print settings in Cura from this link.

There are some tips and tricks for the FDM 3D printing. According to your printer there are certain capabilities of your printer which you can use in your design to be more effecient in time, material usage and quality.


You can refer this document to know about tips and tricks in detail.

Group Assignment

Our group assignment was to test the design rules for our 3D printer, Ultimaker 2+. Then we began our search in opensource platforms like, thingiverse, grabcad, cults3D etc to find out is there is any 3D which we can use to test out printer. We came out with different models and selected one for testing our 3D printer.

Following process was followed to print the files 

  • Load the file in the cura and use the following settings

 - Layer Height: 0.2mm
 - Shell thickness: wall= 0.7mm,
    Top/bottom =0.75mm
 - Infill: 20%
 - Material: Generic PLA
 - Speed: 60mm/s
 - Travel: Retraction checked
 - Cooling: 100%
 - Support: None
 - Bed plate adhesion: Brim

  • After everything is set up, click on slice and export the file to the external memory card
  • Connect the printer to the power and turn it on.
  • Now after the printer is powered on please make sure that the bed is flat. There are three mannual screws below bed which is used to flatten bed manually. Refere the the mannual mentioned above for the process to make the bed flat.
  • Make sure that the mateial is loaded
  • Insert the memory card in the printer
  • Use the navigator and click on print and select the file and the printer should start printing

Following were the observations:

  1. Overhang: Over hang of draft angle 45 degrees could be printed without support
  2. Bridge width of 25mm is possible without support and 100% cooling
  3. Max height for 2mm x 2mm column is 12mm
  4. For cylindrical holes: deviation in diameter=0.12
  5. For rectangular holes: X-deviation=0.08mm, Y-deviation=-0.15mm
  6. For thin extruded cylinders: deviation in thickness=0.2mm deviation in outer diameter=0.22mm

These capabilities and deviations should be accounted in the design to reduce time, material usage and quality of the print.

Individual project

I had used 3D printer for printing some of projects as shown below:

For this weeks individual assignment, I tried to design a chain which have flex in all direction. I want to make it like a fibre like srtucture. Taking considerations of the overhang, I tried to make an interlocking design.

STEP 1: First I started with a simple wavy shave inside one another that chan build a chain and tested.


STEP 2: I tested the part. Though it was working, it was not as good as I had expected, it was due to the small diameter of the part. Also there was so loose. So i thought of using a bridge and make a similar shape but by using a rectangular shape. and designed another.


STEP 3: I printed a small part to test it. The flex was good and print quality was improved. Then I though of creating a skin above it so that the interlocks remain hidden inside. then tested a small size.


STEP 4: After all test was good, I used the Boolean command with parametric design to arrange it in array then added a cut to snap fit the outher side for making the bracelet.


STEP 5: Then I exported the file in stl format to slice it with Cura.


STEP 6: I Used cura to slice it using following setting:

  • Layer Height: 0.2mm
  • Shell thickness: wall= 0.7mm, Top/bottom =0.75mm
  • Infill: 100%
  • Material: Generic PLA
  • Speed: 40mm/s
  • Travel: Retraction checked
  • Cooling: 100%
  • Support: None
  • Bed plate adhesion: Skirt

Finally, the print was ready and the product after iteration was like the figure below.


3D Scanning

Application used: a. Qlone, b. Scandy pro

We will be using Artec 3D, a professional scanner for 3D scanning. Meanwhile I tried Qlone but was not free so could not export stl file from it. Qlone is a software which uses a reference sheet to locate the actual object to be scanned. It takes multiple pictures and use photogrammetry to create a 3D model from it. It use at least two or more image to locate a point in space and use it to make a 3D. Following process is used to scan an object from phone.

1. Print the paper and place it on the table with good lighting condition.
2. Place the object in the center of the paper, open the app, start recording and move it around the object to uncheck all the grids.
3. After the scan it should automatically make a 3D file which you need to pay to export in stl format.

Then I used Scandy Pro, in which we can scan and export one file for free in every 24 hr. This software uses the front two cameras with the depth map that Apple's TrueDepth sensor provides to mesh the points together to create a 3D scan. you need to be in really good lighting and steady hands to scan.

To scan, after the app is installed, you need to move it steadily around your face so that the algorithm can refer consecutive frames. Since it takes multiple photos, your mobile is going to heat up very fast and battery will also drain fast. It makes very fine mesh for the scan you do. 


After the scanning was done I used mesh mixer to extract the surface i wanted.

1. Import the scanned stl file to meshmixer
2. Slice the unnecessary part using tool.
3. Now select the required part by using select tool and click on separate and delete unncessary part.
4. Then you should have the remaining portion which you want to use.
5. Now insert the plate you want to take it as a base, combine it and export as stl.
6. The part was printed and you can see the result.

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