3D Printing

What is 3D printing?

Additive manufacturing (sometimes referred to as rapid prototyping or 3D printing) is a method of manufacture where layers of a material are built up to create a solid object.

4.Removal of Prints

For some additive manufacturing technologies removal of the print is as simple as separating the printed part from the build platform. For other more industrial 3D printing methods the removal of a print is a highly technical process involving precise extraction of the print while it is still encased in the build material or attached to the build plate.

5. Post processing

Post-processing procedures again vary by printer technology. SLA requires a component to cure under UV before handling, metal parts often need to be stress relieved in an oven while FDM parts can be handled right away. For technologies that utilize support, this is also removed at the post processing stage. Most 3D printing materials are able to be sanded and other post-processing techniques including tumbling, high-pressure air cleaning, polishing and colouring are implemented to prepare a print for end use.

Material Considerations

Choosing the right type of material to print a given object is becoming increasingly difficult, as the 3D printing market sees the regular emergence of radically new materials. In FDM 3D printing, PLA and ABS have historically been the two main polymers used, but their initial dominance was mostly fortuitous, so there should not be any major roadblocks for other polymers to play a key role in the future of FDM.

Methodology

Materials are usually graded along 3 categories: mechanical performance, visual quality, and process. In this case, we further break down these categories to paint a clearer picture of the polymer’s properties. The choice of material really depends on what the user wants to print, so we listed the key decision criteria needed to choose a material (other than cost and speed):

Understanding 3D Printing Tolerances

The following links talk about guide to understanding the tolerances of your 3D printers and also using them for engineering fits. They talk about the general problems faced during 3D printing and how to overcome them

So its wise to printout scales such as these to understand the parameter of your printer and understanding its tolerance.

Models of such scales can be downloaded from here:

Printing

The idea is to print something that cannot be made by subtractive process. I wanted to print something kinetic. After listening to Mr. Ohad(Regional Instructor) and Mr. Neil during the lecture where they explained about various kinetic projects that were printed in 3D I wanted to do something on that line as well. After searching for various reference and mechanism on the net I came across this youtube page

He is a mathematician and his 3D printed items were unique and intriguing. I decided to print a network of hinge system after being inspired by one of his designs. I took Fusion as my CAD tool to design this. I was quite nervous as I've never done a precise model in Fusion before.

Fusion

I started with the basic sketching of the mechanism after deciding on the size of each unit. Once the base unit was done it was more of replicating to form a pattern. Now since this is a hinge design I need to consider the tolerance for the parts to move freely. So I had the outer diameter of 2.7mm and the rod diameter as 1.5mm hence leaving a tolerance a little more than 1mm.

Once the design was done I exported this as a .stl file and opened in Cura which is Ultimakers native splicing software

As suggested by my regional instructor I didn't want to go for the default setting of the software but to explore all the parameters myself. I am new to Cura so it took me some time to get accustomed to then UI and requirements. I had the layer height as 0.2mm and the infill to 5%. Since this was only a test print I wanted it to keep it as minimal as possible. I used the general supports and brim support of 3mm. Another important factor that, must be checked is the material and the nozzle size. This determines all other parameters.Once all the setting were ready I made a GCODE file of the same and took it for print.

Using the printer was actually easy. Once the file is loaded it's all about checking the parameter if they are fine and then printing. I used PLA to print. PLA is harder than ABS, melts at a lower temperature (around 180°C to 220°C), and has a glass transition temperature between 60-65 °C.

In Ultimaker once the material is mentioned the printer sets all other parameters. So its necessary to specify the right material that's being used. When the light hovers over the file to print it displays all the information about the print like the nozzle size and time taken to print. Etc. This is a basic checklist that must be accounted before printing.

-Check the material type and amount in the spool

-Load the correct file

-check the material setting in the software

-Clean and balance the build plate

-Apply some glue over the build plate for better adhesion.

Once all the parameter is correct the file can be printed. Its advised to stay near the printer at least until the first two layers are done cause this is where a print can usually go wrong.

Once the print is done, the glass needs to be unclamped from the plate, caution should be taken as the glass will be really hot. Using the right tool the models need to be lifted off the glass surface.

Once I had removed the print I tried to bend it and it snapped immediately. The supports did a needful job while printing yet the whole out was messy. The loop was too small and when tried to bend all the stress at a single point resulted in fracture.

Having understood the reason for failure I went back to fusion to increase the loop size

And then tried printing again with almost the same parameters, and this time the print turned out great and the hinges were moving without a problem.

And this is after removing all the support materials.

Once I knew the design was working I wanted to print a network of them(a grid of 5x5) as a final output. After modifying in Fusion went on with the printing process again.

But unfortunately, I ran into trouble with the printer. The whole process was about 2 and a half hours but after about 1 hr there was no material coming out of the nozzle. I had to stop the print and examine the fault of the printer. Having figured that it could be a nozzle problem or the material spool tried rectifying them and re-printing the same.

Again the results were the same. After an hour of print, the material would stop. A similar problem occurred with a file of my colleague.

So to complete my print I scaled down the model size to a grid of 2x2 and this time tried printing without supports, and the result was amazingly clean print with smooth movement.

Was really delighted to see how the prints had turned out.!!

Scanning

3D scanning is a technique to capture the shape of an object using a 3D scanner. The result is a 3D file of the object on a computer, which can be saved, edited, and even 3D printed. Many different technologies can be used to 3D scan objects, environments, and people; each technology comes with its own limitations, advantages and costs.

The 3D scanning technologies rely on different physical principles and can be classified into categories:

Laser triangulation 3D scanning technology, as illustrated on the image, projects a laser beam on a surface and measures the deformation of the laser ray.

Structured light 3D scanning technology measures the deformation of a light pattern on a surface to 3D scan the shape of the surface.

Photogrammetry, also called 3D scan from photographies, reconstructs in 3D a subject from 2D captures with computer vision and computational geometry algorithms.

Contact-based 3D scanning technology relies on the sampling of several points on a surface, measured by the deformation of a probe.

Laser pulse (also called time of flight) 3D scanning technology is based on the time of flight of a laser beam. The laser beam is projected on a surface and collected on a sensor. The time of travel of the laser between its emission and reception gives the surface’s geometrical information.

Kinect

Kinect is a line of motion sensing input devices that was produced by Microsoft for Xbox 360 and Xbox One video game consoles and Microsoft Windows PCs. Based around a webcam-style add-on peripheral, it enables users to control and interact with their console/computer without the need for a game controller, through a natural user interface using gestures and spoken commands.

Microsoft released the first Beta of the Kinect software development kit for Windows 7 on June 16, 2011.[15][16][17] This SDK was meant to allow developers to write Kinecting apps in C++/CLI, C#, or Visual Basic.NET.

 Hardware

The Kinect contains three vital pieces that work together to detect your motion and create your physical image on the screen: an RGB color VGA video camera, a depth sensor, and a multi-array microphone.

The camera detects the red, green, and blue color components as well as body-type and facial features. It has a pixel resolution of 640x480 and a frame rate of 30 fps. This helps in facial recognition and body recognition.

The depth sensor contains a monochrome CMOS sensor and infrared projector that help create the 3D imagery throughout the room. It also measures the distance of each point of the player's body by transmitting invisible near-infrared light and measuring its "time of flight" after it reflects off the objects.

Scanning

To connect Kinect to my Laptop was very simple. I had to download SDK (Software development kit) and then it was just plug and play.To scan using Kinect I used Skanect, ReconstructME, and Shapify.

Shapify

Shapify is primarily a 3d printing store. They have a scanning software which can be used to scan yourself and send them to print directly.

Using the software was very simple. Connect your Kinect and start scanning.

The person needs to rotate 6 turns for the system to scan the entire 3D model and generate an output. In each position, the Kinect head moves from the foot position to the top of the head. After patient scanning process, the combing of the images process took place

The output was very disappointing. The software was not able to render the images as a proper 3d model. The result was just an overlap of several images and that too not done properly.

Skanect

Skanect was a really good software for scanning. It can be used with various sensors like Asus Xtion, Primesense Carmine etc apart from Kinect. It is licensed software although the free version offers great features with limitations. The software can be downloaded from here

The software was pretty simple to use and didn't require any tutorials, to begin with. Once the program was started the software looks for any connected scanning devices. Then u can create your new project by clicking the new button. This offers a variety of option that u can select depending upon the nature of the scanning.

To experiment with this software I decided to scan a clay model. This basic interface displays the color image, the depth layer, and the scanning area.

Once the scan starts all the area that is being tracked is lit green and the areas that aren't scanned properly is lit in red, so the sensor can be adjusted accordingly.

When the scan is complete the software run to compile the images together to form a 3D mesh.

The software also includes basic post-processing tools to correct the scan. The model can be edited for color, mesh, Geometry etc.

Once all the processing work is done the model can be exported as 3d files to be opened in other software or to sketchfab for internet viewing or for print. In the trial version, the exporting and saving comes with limitations.

Hence I wasn't able to save my scans and the ones that I could were in the form of a very low poly mesh. But I was able to upload them to sketchfab and here are the results.

These are the two models that I scanned using Kinect in Skanect. The results were good but the meshes were smooth with fewer details, the color and texture reproduction was average.

Reconstruct ME

Reconstruct ME is another great software for scanning and its free. The tool can be downloaded from here

The UI is simple and up to the task. As soon as you open the software its starts searching for connected device and begins with the setting up process. Like Skanect depending on the scan adjustments can be made to the volume of the scan area.

Once you click on new scan, after the preset delay time the software begins with the scanning process.

But I was a bit disappointed because after using Skanect the scan recognition was very bad in this. It took several attempts to complete the scan properly. Also, the software does not offer and processing tools.

But once the scanning was done the results were good. The Output had more mesh geometry making the model has more details to work with. The texture and color reproduction was bad and slightly displaced. On the whole, it was really great and easy using Reconstruct ME.

Recap Photo

Recap is by Autodesk and it scans objects by the process of Photogrammetry. The software can be downloaded from here

I downloaded the trial version but later got upgraded to students license. Recap is cloud-based software.  Again like the other software, the UI is simple and the software is very easy to use. On opening, the software presents the mode of image input an in my case its object. That opens another window where the photos need to be uploaded

There are 2 rules to scan an object in Recap. The photos taken must at least overlay by 60% with each other and 20pics is a minimum requirement for scanning. The shot photos are now opened and clicking create will first upload all the photos on to the cloud server and then compute them. It might take some time to compute depending on the server load.

The results of the scans were really astonishing. The software has stitched all the data neatly into a model. The model had a lot of details and the mesh generated was really intricate. I found this method though not accurate, better than scanning with Kinect, because the model, texture and color reproduction was far better here than that of the previous scan methods.

Meshmixer

Meshmixer is by Autodesk and is state-of-the-art software for working with triangle meshes. Its a really great software and is free. It can be downloaded from the following link

All the models that are achieved by scanning are raw and the and the meshes need to be edited if they are to be used for any other purpose such as printing. This software acts as a bridge between scanning and slicing. On a personal note its a really great software. This is my first experience using it and it was tremendously powerful and easy to use. I rally had fun using this software.

I decided to print the scan model that I obtained from Recap. I imported the file into mesh mixer

Using the select tool I painted over all the necessary areas and deleted them

Over In the analysis option, the inspector tool helps identify holes or defects in the model that need to be rectified.The pointed areas need to be closed in my model and this tool helped me achieve that

Using the cut plane tool I gave the model a neat base which makes in printable.

I decide to generate supports from mesh mixer to see how it works. The supports can be generated using the overhang tool in analysis option. Using the default setting of Ultimaker I generated supports. My first impression was that the supports loom very different from that of Cura.

To compare the two software I took the model into Cura and saw the time and material required to print this model and the one in which the support systems are generated by Cura keeping all other parameters same.

 Actually, the one with Meshmixer was slightly lower than that of Cura though it was a negligible amount. But the size of the model matters. Since this model is small the change isn't much but I suppose the difference will be vast when it comes to complex models. So I began printing the model with Meshmixer support systems.

The model came out well and the support systems were up to the task. That was not all, the support systems were designed in such a way that only a point of it was in contact with the actual model. Unlike Cura, removing the support structure was really easy and it did not mess the model at all. =D

The scanned model and the printed junior

Conclusion

As I said earlier this whole week is about translating from the software realm to the physical realm. I wouldnt say it was easy but it was fun. I got to learn a lot of new softwares most of which were pretty cool. All the process be it scanning or printing are very simple processes but since we are only used to 2D, adding an extra dimension to these ordinary tools was fascinating. I guess I've only scrapped the surface of 3D printing considering Neil's lecture about various types and kinds of 3D printing.  What I learnt from about 3d printer is that, there are various factors that affect the  print, like the nozzle size, layer height, retraction, speed etc. I guess all machines have their tolerance that need to be worked around. It takes time to understand what the machine needs and how you extract what you require from it. The use of Kinect was really helpful as I might use it in my final project for scanning. Now I know the basic working of it, I'm yet to explore its complete potential and applications. On the whole this week was great and had lots to learn.

Files

All files can be downloaded from HERE

PART 1

PART 2

PART 3

PART 4

PART 5

Fusion Files (Native)  (Universal)

NOTE:

As the 3D files sizes are heavy I had to split all the files as multiple smaller files. Download all parts and extracting one file will automatically extract all other files as well.