Aim:
To learn and understand about the processes involved in 3D scanning and printing
Task 1:
Processes regarding 3D scanning
Sub Task:-To identify and understand the process of 3D scanner.
The proecss that we use for 3D scaning is photogrammetry, which is basically the method of digital imaging.
In this process you scan a real life object, as an image made out of pixels.
This type of scanning actually dosent give you the perfect form of the image or the geometry, but rather gives you the surface image about how the body might be viewed through a camera, in the perspective of a 3D model.
Sub Task:-To install the software for 3D scanner
The installation of the machine software was not much difficult.
The software that we used was the default software provided by Sense, (company whose 3D scanner we use). For this you just get the setup downloaded and install it using the default parameters.
Then to configure the device you need to connect the scanner to the USB of your machine and then open the software, and follow the instructions that come by..
Sub Task:-To understand the process and properties of the scanner
The scanner that we have (product), is a portable scanner by Sense, which works on the principle of photogrammetry as explained above.
There are following steps and precautions ment to be taken while operating this device....
- Plug the device to the USB and boot the software.
- Select the mode of the software for working, (this one efficiently supports 2 modes, being human and object)
- If you select human you have again have to select full body or the top body, which actually provides a very versatile interface...
- In the other context of the object it give you options about the sizes of the object, small, medium or big.
Initially i had a thought that this won't affect much what ever you choose, but over a few tries i figured out that, that actually adjusts the referance distance for the IR sensor installed, which helps in better forming of images.
- Then the next thing you can do is the setup of the object to be scanned..
There are two possible ways to scan a object
1. By keeping the scanner fixed and rotating the object on a turn table about its axis
2. By keeping the object stationary and rotating the scanner around it
- The next step is to start the scan rotate the part smoothly without much breakage
- Further the part remains is about the rendering and saving the part that can be analysed during the process, since the software helps well graphically
My experience with the scanner.
I tried to scan three objects out of which these were my colcusions.
- Initially i tried to scan myself, where i kept the scanner steady and then rotating myself on a turing stool, out of which I got this result.
- The scan was distorted because the turn table was quite unstable which we repaired later.
- The next issue was, I was mannualy rotating the turntable myself, which didn't go well as expected.
- Then there is a limitaion of resolution that we didnt consider, the distortion near the ear is because the scanner was not perftly able to scan my scattered hair, that let to the distortion
Hence I concluded that the resolution, complexity and the orientation of the object and the scanner has to be taken into consideration - The next object that I tried to scan was my drum pedal, where i kept the pedal steady and rotated the scanner, this time also I didn't succede and plotted the following conclusions.
- The rods of the beater are not printed beacause they are shiny and reflect most of the light and that fools the IR sensor and hence the camera.
- The pedal dosen't appear in the scan as it does in real life, its because our eyes are capable of imaging the difference in the light, where as the gets confused when the there is a non uniform reflection of light, which happend in the case of the foot board of the pedal
- The resolution again cause a nuisance here too, if the part of the spring has to be considered where it has dot a detailed serrations
-
This was my final take where i chose a simple object (My wallet), considering the limitations of the scanner, and prefered the method of keeping the scanner steady, since rotating the scanner is a matter of skill.
Hence this was the final image I got out without any rendering....
For this i had a different experience and some conclusions as listed below..
- The above coclusions all stand true for this scan too
- There is a loss of track of the image where there is a sudden rise and fall in the geometry of the object, for this you have to refocus the object by adjusting the scanner for that particular section of the image.
This was the method i realised and scanned the inner parts of the wallet - The scanner dosen't loose the track on loss of continuity in scanning, the scanned image is already been recorded, hence the object can be scanned in sections part by part, yet the backend of the software solves the math and gives you the almost perfect apperarance (considering it's resolution)
Sub Task:-Problems faced with scanning part
Initially I had scanned the part as it was seen above, but the issue was if I had decided to print it, it was not clean enough, basically the base would also have been printed with the wallet, hence now the task was to edit the STL file.
That was basically a tedious task, yet following was the edit I was able to make, and here was the process which I followed:-
- This entire session was constructed in mesh mixer.
- First we import the STL file into it.
- Later you select to sculpt the object, and then flatten it, using the necessary parameter, where you are able to shrink and delete the unwanted sides of the STL file to get this as the final output.
Task 2:
Processes regarding 3D Printing
Sub Task:-To identify and understand the process of 3D Printers.
The type of printers that we have are FDM [Fused Deposition Modeling], in this method the printer heats up the material which is fed from the nossle on a heated bed.
The material is stored in the form of a wire on a spool of appropriate weight(not too heavy or too light).
The nossels travels on the path which has been fed in terms of G-codes through the respetive softwares, recommended for the printer.
The software is stuffed with the backend interface which generated G-codes considering the properties of the printers.
The materials in this process are just heated near to there melting temperatures where they are left to be soft enoiugh to be extruded but cannot melt.
Hence in this process maintaing the temperature of the bed and the nossle plays a crucial part.
Sub Task:-To study various properties of the 3D printers that we have.
We have two printers in our lab, both are FDM as discussed above:-
1. Accucraft i250+
2. Fractel Works Julia
To begin with we start with the specification of each printer:-
- Accucraft i250+
- This printer has a bed size of 300mm X 250mm X 200mm
- The printer is commanded by software named as 'Key Slicer', which respectively generates the CAM path for the nossle
- It supports a filament diameter of 1.75mm
- Has a nozzle diameter of 0.45mm
Above written and more, are the technical specifications of the printer,which can be used to generalize the printer
- Fractel Works Julia V2
- This printer has a bed size of 210mm X 250mm X 260mm
- The printer is commanded by software named as 'Fracktory', which respectively generates the CAM path for the nossle
- It supports a filament diameter of 1.75mm
- Has a nozzle diameter of 0.40mm
Group Assignment
In this part of the assignment we had to describe various properties of the printer which are actually seen, rather than on paper.
Hence we decided to load the pronters with few tasks having particular parameters to define, and then judge various outcomes that are seen through it.
Following are the properties we found essential for our desiging parameters and evaluation analysis for each of them:-
- Base area VS Permissible Height:-
The objective behind this test was to see the height for a standard base area untill which there in no distortion in the material
For this we made a circle of columns, with a base of 1.5 X 1.5 mm and increased the heights from 10mm to 50mm, and got a pattern which looked as follows
During this process we got a distortion pattern as follows
Out of this we concluded that the permissible height at which the structure can have natural strength is upto 25mm, after which the strength begins to deteriorate, and at a length of 50mm it show lowest strength and maximum distortion
Hence to conclude the Base area : Height ratio for perfect structural strength is 1sqcm : 20mm - The next test we conducted was something we called as point test:-
The objective here was to diagnose the accuracy of extrusion of the nozzle, we knew that the diameter of nozzle was aproximately 0.4mm.
For this test we developed a structure which is shown below, having an upper point of 3.5mm
After the print we got a finest measurement of 0.54mm
Hence we concluded that the printer can obviously can't extrude below its nozzle size, rather it has a normal extrusion difference of 0.14mm - The next thing we desired to test was the placement of objects, this was one of the most important test, since by laws the object has to be perfectly placed in order to have a desired structural strength.:-
For this we made an "L" shaped object, and arranged it in the positions shown below.
Out of which we got a result as follows
Hence we concluded:-
1. The shape which was laid down horizontally had better structural strength as compared to others
2. The vertical shape standing as 'L' had good structural strength but not as good as inital one
3. The object standing like inverted 'L' had hanging from its streched part and laked a proper strength
Hence to conclude we exclaimed that the object having maximum surface area at the base has the best structural strength, if compared to other arrangements. - The next test was the Hole test:-
This test was taken to calculate the accuracy of the interpolation of a hole, if the printer interpolates a hole of desired size or it has some inaccuracies
For this we printed a pattern of interpolation at different qualities{Fast, Normal, High, Ultra}, in order to compare the in accuracies
After analysis of which we got following results:- 1. The holes interpolated at fast have a significant inaccuracy of 0.5mm
2. They are followed by Normal, having a difference of 0.3-0.4mm, than the actual size.
3. Then we have holes made at High quality, which do not differ much but still have an inaccuracy of 0.3mm
4. At last we have holes interpolated at ultra quality(expected to be at perfect size), they also lag by a measurement of 0.1mm
Hence to conclude what ever the quality the printer would have and marginal inaccuracy between 0.1mm to 0.5mm - The next test we did was about enfilling according to difference in print quality:-
The purpose behind this test was to test the printer's enfilling capacities, which could be needed for prototype objects that could need higher strength
For this we printed following boxes and plotted our results as follows:-
1. The cube which was printed at 'fast' quality, had brittle and poor joints, which can usually be seen in support structure, also it had distortions as viewed below, like the treads came out and a layer was ill printed
2. The cube printed at Normal quality, had a fairly good strength at joints, still has some irregular voids, and distortions near ill printed layers, but comapratively stronger joints.
3. The next cube was printed with High quality settings, which as seen has no voids a good joint strength and a light distortion for a point which could have been excessively heated, as seen below
4. The last cube was printed Ultra settings,this cube had asolute no issues with the enfilling and voids, rather the dimenssions of the prnt were highly accurate, as can be viewed
Hence we concluded insorder to get highly precise objects, the quality has to be set for the default settings of ultra, where you get a perfect desired object, which actually costs you ample of time.
Thus considering all the parameters we went to next task to design an object.
Task 3:
Desinging a part and getting it printed
Sub Task:-A random design.
For this part of the assignment it was a must for us to make a 3D dsign that can't be manufactured by any of the subtractive process of manufaturing, considering above parameters calculated about the machine.
**Now the question is what are subtractive processes of manuacturing??
The processes which involve manufaturing of a particular job, by removing material from a raw block are to be termed as subtractive process of manufaturing,
These include...
1. Milling
2. Turining
3. Casting
4. Forming
and many more
Hence considering the above parameters I decided to develop a show piece, that could be creative by the aspect of desining and could cover all the conditions required above.
It basically is a representation of a drum kit.
All the images above are representations of a drum kit, which stands on a pedestal
The reasons why each of this part is not possible to be manufactured by subtractive methods are described below(even if scaled up)
- Pedesal:-
The Pedestal is designed such a way that it has a material twist in the (alpha) axis which makes it difficult for a normal 3 axis milling machine or a turing machine to manufature.
{Rather the manufacturing of this twist can be attempted to be manufactured over a 5 axis milling station}
Then after this object is possible to be casted but the issue here is about the precision of the die to develop the twist and the nozzle from where the material is to be injected
{Possible ways blowmolding and injection molding or roto molding}
All if the mould is developed with precision.
Other methods such as forming of turning rather won't work in this case.
Hence I decided to develop this in 3D printing - Other Pieces of the The drum:-
The peices mounted on the pedestal, as said above, are representations of a drum kit(Displayed in the image above).
These designs are not immpossible to get done by subtractive methods, but for these there have to be numerous methods to be combined at once to get the job done.
These pieces can't be milled because initially they have 3 faces which are to be machined at once which becomes a major problem when it comes to clamping,
{The possible method for this is using a magnetic pad, for which there has to be a specific requirement of no ferrous tool(Carbide tools) which tend to increase the cost extensively.}[Points marked in the image are relatively difficult to be milled in one setup]
Also there are hexagonal slots on the faces of the drum which represent the tunning bolts, these are tapering towards the inside thus there is a decreasing diameter which becomes a massive problem if to be generated by endmill
{Possible ways are either to make a mold that has insertions like these, or either a special tool that has the arrangement equivalent to the slots, which could just plunge into it.}
More over considering individual objects, the Base drum has holes on the top, to generate which either you have to make it in a different setup of orientation, or need a 5 axis milling machine or a HMC.
Considering the geometry of the snare drum the diameter at the top and bottom are nearly equal, for this we'll need a special tapered tool or could be manufactured over a turnmill
Hence considering these complications I decided to go for the process of additive manufacturing.
For this the material that I had used was PLA (Poly Lactic Acid), this is a soft material having a melting point of 130degrees celcius.
The parameters I had used were:-
Speed:-50mm/s
Bed Temperature:-60 degree celcius
Printing temperature:- 210 degree celcius
Fill density:- 90%
Then after printing i placed these objects in the arrangement shown below...
Sub Task:-To develop a part of project
During this process, I also decided to make a part that can be used in my project.
The part is a simple hopper which fits on the mixer as the image expresses below..
This part is actually very simple in design but it cannot be manufactured by the prototyping methods available or which can be considered, reasons as specified below:-
- Milling:-
a. This object is difficult for milling because of the tapering sides of the object (inner and outer).
b. Then other this there is clamming issue again that this job can't be manufactured in one setup, it's a must to flip the sides.
c. Besides the job takes up a heavy material and manufacturing cost if considered for prototyping - Casting:-
The job is difficult to cast because of the angles in the hopper would be difficult for the process of nomarl moulding
{Rather the processes of rotomoulding can be applied over here but the issue is again of the costing in making of the moulds and the material to be choosed} - Then there are two best possibilities for this job to be done, but they go bit far beyoud the concept of prototyping, those are forming, and manual fabrication:-
In the case of forming, the process is only affordable in mass production.
And in case of fabrication it's easy and affordable but the overides the concept of digital fabrication and prototyping
Considering these facts I decided to go with the method of 3D printting
This is the final product that i got, after a hilarious delay of 8 hours but got a satisfactoy results as seen in the picture below
The job actually took more time because of the mesh of support structure, which was necessary to maintain the geometrical slopes
I made entire of my job on JULIA V2 since the accucraft at the lab was misbehaving for some reasons Following set of images will guide you through the printing your job using accucraft julia
Advantages of Subtractive Manufacturing
To conclude we can say, considering all the methods of subtractive manufacturing, there is no job that can't be manufactured using these methods, by some or the other ways.
The processes just include combining these methods as per requirement and economic arrangements.
On the contrary these processes are fast enough if considered for big and complex objects as compared to the additive methods of manufacturing.
These processes are great in terms of manufaturing cost and time, for heavy batch prodution
The above can be plotted as the advantages of subtractive manufacturing that it has over the method of additive manufacturing.
Advantages of Additive Manufacturing
On the other hand if we consider about the methods of additive manufacturing, it constructs complex pieces at one go without any requirement for change in arrangement.
This feature enables you to make any complex geometry
Also the process mentioned above are easy but the setup of these machines is super expensive in comparison with a slow 3D printer.
Secondly the amount of technical knowledge needed to operate these machines with desired parameters it too high, where as for a 3D printer you just have to design and print with the desired quality, (which can be automatically managed by the software, if new to it).
The softwares are capable enough to generate the G-codes for the printer from a *.stl file.
The machines are good for the considerations of prototyping, but fail in productivty due to the rate of flow of the material.
Hence above are the analysis points for both the processes and machines.
. . . . . .