3D Objects, Engineering, Optimizing 3D Prints, Sustainability

Optimizing 3D Prints: Results: Optimum Configurations for 3D Printing (Part 2)

Results: Optimum Configurations for 3D Printing

The summary of optimal settings obtained in the case of Experiment-1 and Experiment-2 can be found in Table 2 and Table 3 respectively. It shows the most ideal and least ideal configurations to use when it comes to choosing between the factors. It also shows which factors, or the factorial interactions contribute to the printed object in a statistically significant manner. This indicates the user to keep an eye on them.

Infill (Factor B) Most Ideal Configuration Least Ideal Configuration Statistically Significant Factors
Low High Height Base Area Height Base Area Height Base Area
Hollow 20% Natural

20%

None

Natural

20%

None

Natural

20%

Tapered

Natural

Hollow

Tapered

C No

Factors

Hollow 80% Natural

80%

None

Natural

80%

None

Pink

80%

Tapered

Natural

80%

Tapered

C B
Hollow Solid Natural

Solid

None

Pink

Solid

None

Pink

Solid

Tapered

Natural

Solid

Tapered

No

Factors

No

Factors

20% 80% Pink

80%

None

Pink

80%

Tapered

Pink

80%

Tapered

Natural

80%

Tapered

A, C

A*C

A*B*C

A

A*B, A*C

A*B*C

20% Solid Natural

Solid

None

Pink

20%

None

Pink

20%

Tapered

Natural

Solid

Tapered

A, C

B*C

B
80% Solid Natural

80%

None

Natural

80%

None

Pink

80%

Tapered

Pink

80%

Tapered

A, C B, C

A*C

Table 2 Summary of the results of the optimal configurations of Experiment-1

 

Infill (Factor B)

Most Ideal Configuration Least Ideal Configuration

Statistically Significant Factors

Low High Height Base Area Height Base Area Height Base Area
Hollow 20% Natural

Hollow

None

Natural

20%

None

Natural

Hollow

Tapered

Blue

20%

Tapered

C

A*C

B
Hollow 80% Natural

80%

None

Natural

80%

None

Natural

Hollow

Tapered

Natural

Hollow

None

C B, C

B*C

Hollow Solid Natural

Solid

None

Natural

Solid

None

Natural

Hollow

Tapered

Blue

Solid

Tapered

C

A*C

A

A*B, B*C

20% 80% Natural

80%

None

Natural

80%

None

Natural

20%

Tapered

Blue

20%

Tapered

C

A*C

A*B*C

C

A*B

20% Solid Natural

Solid

None

Natural

20%

None

Natural

20%

Tapered

Blue

Solid

Tapered

C

A*C

A, B, C
80% Solid Natural

80%

None

Natural

80%

None

Blue

80%

Tapered

Blue

Solid

Tapered

A, C

A*B, A*C

A*B*C

B, C

A*B

Table 3 Summary of the results of the optimal configurations of Experiment-2

 

When color pigments are added to natural PLA, some of its properties such as crystallinity is affected [25], leading to variation in the way the material prints. Hence, a similar experiment was performed with two different pigmentations of PLA. Factor A’s levels were changed to pink and blue. However, other factors and the settings were kept the same. The expected values also remained the same. Table 4 shows the optimal configurations for the Experiment-3.

 

Infill (Factor B)

Most Ideal Configuration Least Ideal Configuration

Statistically Significant Factors

Low High Height Base Area Height Base Area Height Base Area
Hollow 20% Blue

20%

None

Pink

20%

None

Blue

Hollow

Tapered

Blue

20%

Tapered

No Factors No

Factors

Hollow 80% Blue

80%

None

Pink

80%

Tapered

Pink

80%

Tapered

Blue

Hollow

Tapered

No Factors B
Hollow Solid Blue

Hollow

None

Pink

Solid

None

Blue

Solid

Tapered

Blue

Solid

Tapered

No Factors No

Factors

20% 80% Blue

80%

None

Pink

80%

Tapered

Pink

80%

Tapered

Blue

20%

Tapered

A, C

A* C

A, B, C

A* C

20% Solid Blue

Solid

None

Pink

20%

None

Pink

20%

Tapered

Pink

Solid

Tapered

A, C

A* C

A, B, C

 

80% Solid Blue

Solid

None

Pink

80%

Tapered

Pink

80%

Tapered

Blue

Solid

Tapered

A, B, C

A*C, B*C

A, B, C

A*C

A*B*C

Table 4 Summary of the results of the optimal configurations of Experiment-3

 

The data from Table 2-4 show that tapered objects should have a lower priority while 3D printing. The bigger the shape, the more accurate the overall geometry [20], hence the cones can clearly be seen having the least ideal configuration in all cases, because the size of each successive layer reduces since they taper. Also, objects printed using natural PLA are consistently seen in the most ideal configuration columns in Table 2-3, making it preferable when compared to its colored counterparts. Choosing the settings available in Tables 2-4 could prove beneficial to reduce filament wastage while printing using PLA.

 

References

References can be found in the Introduction section.

3D Objects, Engineering, Optimizing 3D Prints, Sustainability

Optimizing 3D Prints: Results: Optimum Configurations for 3D Printing (Part 1)

Results: Optimum Configurations for 3D Printing

When the factorial analysis was performed, each of the three experiments had six sub-experiments for every combination of the infill level. Each of these sub-experiments produced graphs and charts for further analyses to obtain the sets of optimal configurations. Fig. 3 shows one example with the pareto chart and cube plot in the case of the second experiment with an infill setting of 20% and 80%. Fig. 4 shows the main effect and interaction among factors with an infill setting of 20% and 80% in the case of Experiment-1. All the relevant graphs and charts can be found in the supplementary material.

The ideal configuration was determined by comparing the fitted means from the cube plot to the expected value. The expected value for the height was 30 mm and for base area was 706.8583 mm2. The pareto chart shows the statistically significant factors in Fig. 3. The statistically significant factors indicate that the differences between these groups are not simply due to a chance and are real, this can be said with a confidence level of 95%, since all the obtained data was normally distributed [18,19].

 

Fig. 3 Pareto chart and cube plot of 20% and 80% infill for height (top) and base area (bottom) in Experiment-2.

 

The experimental factors can show effects such as main effect and interaction effects. The main effect is the effect of one factor on the experiment while ignoring the effects by all other factors. It shows how much the average performance of one level differs from the average performance of another level [18,19].

In different settings, different factors show main effect. For example, the plot in Fig. 3 indicates that the infill factor doesn’t show main effect, because the plot is nearly parallel to the central line of average. However, the color and the shape of the object show a significant level of main effect.

In the case of the interaction plot, which shows whether one factor affects another [18,19], the graphs make it very clear that the tendency to interact is high when the lines are intersecting. Henceforth, if two or more factors interact, they are indicated using an asterisk between them.

 

Fig. 4 Main effects and interaction of 20% and 80% infill for height (top) and base area (bottom) in Experiment-1.

 

References

References can be found in the Introduction section.

3D Objects, Engineering, Optimizing 3D Prints, Sustainability

Optimizing 3D Prints- Experiments: X-ray Tomography

Experiments: X-ray Tomography

A powerful technique in determining the internal structure of closed objects is X-ray computed tomography (CT) or simply, tomography or CT scan. A beam of X-rays is projected on the desired specimen. The radiation transmitted by the specimen is captured by an optical receiver. Images are captured for each discrete rotation of the specimen, and they are reconstructed into a 3-dimensional density map. This map can be used to observe the internal structure and determine its flaws and structural inhomogeneity [5,12,16]. It can also be used to determine minute morphological variations. A Bruker Skyscan 1172 Micro-CT scanner was used to perform this experiment. The specimen here is the 3D printed PLA object using the FFF printer. This is placed using a mount and a paraffin film, so that there is no movement. This film is transparent to X-rays.

It was important to choose an appropriate voltage to keep the power supplied very close to 10 W, so that the X-ray source and the transmitted X-rays from the specimen remains high. A low voltage would result in an inefficient capture of images by the receiver [5,16]. The voltage chosen here was 44 kV. The corresponding current was 222 mA.

When objects were scanned, the captured dataset had 631 horizontal cross section and 1000 vertical cross section slices of images. When it came to the scanning the outer shell, 641 images were captured for pink cones and cylinders, whereas 901 images were captured for the transparent cylinders. The resolution of the obtained images was set to 1K (1000 x 666 ppi for the outer shell, 1000 x 632 ppi for the vertical cross section, and 1000 x 1000 ppi for the horizontal cross sections). The images were captured for all 4 infill levels for natural cylinders, and for both pink cones and cylinders.

 

References

References can be found in the Introduction section.

3D Objects, Engineering, Optimizing 3D Prints, Sustainability

Optimizing 3D Prints- Experiments: Statistical Conformity

Experiments: Statistical Conformity

While determining the quality of the 3D printed objects, it was important to make sure that all the prints conformed to the specification. The two measurements of interests were the height of the object and the diameter, as they are required to determine surface area of the objects. When the right-circular cone and right-circular cylinder were modeled, they were designed to have a height and base diameter of 30 mm each. The statistical software, Minitab was used to analyze the data. Three factors were considered.

The first was pigmentation. It is important because it has an influence on the final print-shape. The user always has an option to use colored PLA filament. Adding colored pigments to natural PLA will give it different properties [25]. For an extruder temperature above 493 K (219.85 °C), the pigmentation becomes relevant as it affects the roughness of the final print [23], hence a lower optimal temperature was chosen. The temperature can also alter the printing material’s crystallinity, depending on its color [25], which will, in turn, affect the appearance of the printed object. In this experiment, the colors used were natural (translucent), pink, and blue.

The second factor was the amount of infill. The amount of infill has a range of 0 to 100%. An infill level of 20% and 80% are commonly used [23], and on top of that, the two extreme levels of 0 (hollow) and 100% (solid) were chosen along with them. For a shorter print duration, a lower infill is chosen, for better stability, a higher infill is chosen [23].

Finally, the third was the type of shape/deformation of the object, i.e., whether it gradually tapered (cone), or didn’t (cylinder). There are several other factors which can contribute to the quality of print such as the temperature of the nozzle, size of the nozzle, rate of filament retraction and many more [9,20,21,26]. They are not considered in this experiment.

Once the prints were complete, they were measured using a digital Vernier caliper for accurate measurements, and the grand averages of the values of the height and base diameter were obtained. The area of the base was also calculated. Each experiment was replicated to check for bias. The test used to perform the analysis was Anderson-Darling test using Minitab. The collected data was confirmed to be normal with a 95% confidence interval, as shown in Fig. 2 for cones of 80% infill. Similar data for other infill levels of all objects also exists and is made available in the supplementary material.

Fig. 2 Graphs showing normality of the measurement data in the case of 80% infill level.

 

In Fig. 2, the factor that determines the significance of the result of the normality test is p-value. Since the p-values were higher than 0.05, the data collected is normal and does not have false-positives. The closer the p-value to 1, the more normally distributed is the data [18,19]. It also shows the standard deviation of the data.

Experiment-1 was a 2k factorial design, where k is the number of factors; each factor has two levels. The pigmentation factors were selected to be natural (translucent) and pink, and the shape was tapered or none. Each time the experiment was performed, only a pair of the infill factors was chosen to keep the levels consistent. i.e., a combination of two among hollow, 20%, 80%, and solid were chosen. Depending upon the combination, an appropriate level was chosen to be the lower infill and higher infill level. This was done to determine the optimum levels of infill if the choice were among the combinations. The shape/deformation factor were tapered and none.

Experiment-2 was the same as the first, except the pigmentation was changed from pink to blue. Finally, Experiment-3 factored the colored PLAs (pink and blue) for analysis. Table 1 shows the factors and their associated levels. For simplicity, they are labelled as factors A, B, and C in the table and henceforth.

 

Factor Level 1 Level 2
Factor A (Pigmentation) Color 1 Color 2
Factor B (Infill) Lower Infill Higher Infill
Factor C (Shape) None Tapered

Table 1. Factors and their levels

 

References

References can be found in the Introduction section.

3D Objects, Engineering, Optimizing 3D Prints, Sustainability

Optimizing 3D Prints- Experiments

Experiments

To determine the optimal configuration, two kinds of analyses were performed on 3D printed objects of select shapes or deformation. The deformation here indicates whether the overall shape of the object is tapering or not. The shapes chosen were right circular cylinder and right circular cones. These objects were printed at different levels of infill and with different colors. The colors are referred to as pigmentation, especially in the figures.

The first was a statistical experiment, performed to determine whether the shapes conformed to the specifications. The second was a tomographic scan to determine the variation of structure and the layers of the printed objects.

The printed layer thickness was set to be approximately 200 µm. The printer used was Ultimaker 2+ Extended. It was set to the following settings: nozzle size of 0.4 mm, nozzle temperature set at 210 °C, default build plate temperature of 60 °C, and PLA filament thickness of 2.85 mm. Fig. 1 shows a selection of print samples of different colors, shapes, and infill.

Fig. 1 Print samples from one set of experiment

2D designs, Engineering, Interactive Design, Optimizing 3D Prints

Heat Maps

It’s 3.14! Happy Pi Day!

A heat map is a graphical representation of collected data, where large data points are plotted in such a way that it represents the concentration of those points through colors. The color scheme depends upon the choice of the user. Normally, a darker color represents higher density and a lighter color, lower density of the data points.

Using heat maps often help identify the flaws within physical objects (if one knows what to do and how to use it), and movements of mouse cursor, or density of visual concentration while eye tracking in interactive displays.

This makes them very useful in user experience and usability studies to understand why people choose certain parts of a website or a software, and where they have their eyes fixed while using it.

Below is an blurred image of a website (left) and its heat map generated (right) while I was testing it to improve its usability.

Below is a time lapse video of heat maps generated by scanning hundreds of layers of a 3D printed object using an X-ray CT scanner for one of my projects, which has something to do with optimizing 3D prints. More on this another time.

 

3D Objects, CNC and Machining, Creative, Engineering

Emergence

Ideas are more or less a mental representation of an object. What thought provoking idea do you have today, I thought some time ago. Then it hit me like a light bulb popping out of thin air in cartoons when the character gets an idea.

Why not make that?

So meta!

Anyway, I had a long desire to make something out of wood, but it had to be 3D. Without any tools in my hand to make a 3D object out of wood, I had to make it 2D. Neither I, nor my tools would budge, so we compromised and decided to make it 2.5D.

Why is it 2.5D? Because I only had access to X,Y and half of Z axis.

In the end, it came out as I had planned. Just like a light bulb popping out of thin air in a cartoon. but this time, out of a block of wood.

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Well, it is called emergence because it emerged like an idea. But it also true that it looks like the idea is still forming while it reveals itself. Enjoy this video, it is a bit longer than usual since this will be my last post on using CNC… For now.

Thank you for reading!

2D designs, Creative, Engineering, Interactive Design

Circular shapes

Circle― the most beautiful 2-dimensional shape, the infinite sided polygon…

No! No it’s not; it’s a limit curve of a regular polygon say the math nerds.

Alright, I agree. But as long as we agree that circular shapes are very pleasing to the eyes. Any object with curved corners looks great― phones, mugs, rings. Even throughout history, circular shapes have influenced the progress made by humanity. I will stop now and get to the point.

So, while designing the Elmentory Atom, I had the option for making these plug and play devices in any shape. Atom itself has 4 types of units. Originally, the plan was to make each unit a different shape. But after doing some research, it was evident that different shapes would be a bad idea. Circular was the best choice.

But, because we were using tiny electro-mechanical components to build them, each unit could not be perfectly circular, but had to have flat edges to accommodate for the rectangular connectors. I don’t know if you can see them― each of them is 35mm or less in diameter― in the images below, but the black connectors align perfectly with the colorful boards.

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Apart from the shape, the other important feature was the symmetry of each device. Each component was placed in a particular spot on the board to make the board look symmetric at least along one axis.

Finally, the most important part (I’m writing this last instead of first because of the title) was to make sure the devices were easy to use. Each of these devices can be connected to one another. But if they are connected wrong, it would not work, yet neither will it harm the user, i.e. the child playing with them.

Each device had a name on the top, and a specific color based on how it operated. Some inspirations were taken from common objects such as traffic lights to specify the color. The bottoms of the devices were mostly white, and helped the child identify if they were connecting the devices correctly.

This project was fun, because I had to literally think like a child to see what could go wrong. Fortunately, there were also several usability tests made with real kids during development to improve the product before releasing it.

 

3D Objects, Creative, Engineering, Redesigning Something That Exists

Infinitely Remoldable Substance

When I was working on Mobility devices for the Elderly project, my team and I had to do design research on why/how the seniors in the greater New York area used assistive devices for ambulation. While we uncovered many different insights, one of the thing that struck out was the ergonomic nature of the device itself.

Seniors used walkers, canes, rollators, shopping carts and also other make-shift devices to support themselves when they moved from place to place. No matter what device they used, it had to be comfortable to use. Comfort here doesn’t equate to the psychological feeling of stigmatization, rather, it is the congenial ease in using the device itself– hence the ergonomic nature.

When working on the ‘Adaptacane‘, we came across many materials to use it for the grip of the cane, such as memory foam. However, the best material that one could possibly use while making the grip of the cane is polycaprolactone (try saying that a few times). This material, sometimes shortened as PCL, can be molded by applying heat from, say hot water, and shaped into anything, including the shape of the inside of a gripping hand. It is also biodegradable!

Let’s look at an example:

The best part of using this material was that it could be remolded any number of times. The handle (white) of the adaptacane prototype below was made using PCL.

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Pretty cool stuff!

3D Objects, CNC and Machining, Creative, Engineering, Redesigning Something That Exists

Fidget

The 2010s can be divided into two eras — the time before and after fidget spinners came to existence. The weird part is that they came out of nowhere, and now they don’t seem to exist at all!

In fancy MakerSpaces, it is quite common to make these using 4 cylindrical ball bearings, and printing the shell. However, where’s the fun in boring old 3D printing? Besides, it takes quite a while to print. And not to mention, there is always going to be tolerance issues, because low fidelity printers are not supposed to be accurate.

Truth be told, using a thick piece of acrylic and laser cutting is perhaps the fastest way to do this. But a laser cutter is limited to cutting at most an eighth to a  quarter of an inch, beyond which one will have to repeat the trace on the piece of acrylic. And this would cost, surprise, surprise… the tolerance.

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Regardless of the backstory, I was thinking of using multiple machines to make something. The plan was to use my trusty desktop CNC milling machine along with the water jet. I used delrin to make the case or the shell, and the caps. Then, I cut a thick piece of steel slab into circles, to give the spinner some weight.  All in all, it worked exceptionally well!

P.S. I’m not making another one, not in this way… ever. Also, I don’t think fidget spinners make good Christmas presents.