Thursday, April 2, 2015

Interstellar TARS Model Project Interim Report - 3

Interstellar TARS Model Project
Interim Report - III

Object: This report will continue to explain the latest work updates. Particularly, this report describes the results from the laser cutter and the conclusion derived from it. At certain point, the report demands some opinions from the public.

I. Introduction
Previously, I mentioned in the report-II that I am going to engrave lines on the surface of the figure to find out if it is an appropriate way of giving lines. Unexpectedly, solutions to this appeared; other attempts were still made. In this report, all those will be introduced and explained. The new designed figure is currently in the process of printing.

II. Engraving
As I said, I wanted to engrave the lines on the surface and draw black lines with a very fine Sharpie marker. I was concerned what if the lines are too narrow to draw the lines or too wide. The only way to figure that out is to try it. I took my prototype to a laser cutter to proceed graving.

Fig. 1. CAD image for surface of TARS [1]
How did this engraving go? First of all, I was extremely concerned with aligning a laser cutter with the figure. The red lines in the Fig. 1. is a dummy lines. I put those lines merely to make it easier to locate the edge of the laser cutter. Because I sandpapered the prototype figure, it was even harder to align the figure to the laser cutter--sandpapering may raked 0.0001 inch or whatsoever, but that was critical for such meticulous work.

Fig. 2. Prototype with lines on the surface [1]
The Fig. 2. is the result of laser cutting. I did not cut through by the way. I used the 'rast' function to slightly give engraving. But then, a miracle happened! I was expecting to fill the lines with a black marker after the laser cutting, but the lines were black! I could not believe what I was looking at. The 3D printed plastic figure was burned, creating black surface inside. This way, I do not have to worry about drawing black lines. I was in such a rapture that this way of production seemed promising (and it is). I tried to remove the black lines just in case. I washed in soap, scratched with my nails, and scrubbed with an eraser. The black lines remained--perfect.

However, I still had to do the second plan for the engraving line since I do not know which way is better.

Fig. 3. Laser cutter is working on it... with too much excessive passion [1]
Another unexpected thing happened. I forgot to calibrate the laser cutter to the height of the figure. Calibration is very important because the focus point of the laser cutter will be disturbed if not calibrated appropriately. Not knowing that, I processed to laser cut the other side of the figure.

This time, the lines were wider but shallow. I figured this is somewhat interesting too. Although the black lines did not appear--the laser power was not strong enough to burn and blacken inside of the lines. However, the lines were wide enough to draw black lines inside.

Before that, the prototype figure was severely blacken because of the fire caught during the laser cutting process. I decided to spray paint the metallic silver again. Even after the painting, the lines were still deep enough to draw lines in them.

Fig. 4. After the painting of the lines engraved without calibration [1]
Fig. 5. After filled the lines with black marker [1]
Very easy to fill in the lines--although few lines were not smooth enough to draw straight lines. I compared this side of the figure to the side where the lines were carved with the laser cutter.

Fig. 6. Lines filled in with black marker [1]
Fig. 7. Lines engraved by laser cutter [1]
I do not even have to ask someone by letting them to look in through a magnifier. Obviously, the one worked with a machine is neat and organized. On the other hand, the one with black marker is a bit dirty, and crude. This suggests that I must use the laser cutter to engrave the lines WITH calibrated laser pointer.

III. Alternative Production
Do you know how much it costs to produce a figure with a 3D printer? Not so cost effective at all! I had to think about how to reduce price of the production effectively. If 3D Printing was inexpensive enough, I would not sue the prototype figure for several experiments. Anyway, I found that acrylic panels were fairly cheaper than using 3D Printer. Thus, I tried that way.

Fig. 8. CAD image for acrylic TARS [1]
I measured the thickness of a acrylic panel and divided the value to width of the figure. According to the measurement, I needed nine rectangular panels to produce one part of TARS. I added lines too since that was is easier.

Fig. 9. Not again. [1]
To tell the result... it was not good at all.
First of all, as laser cutter cut the acrylic panel, the figure started to bend because of the heat. Of course, acrylic panels are more vulnerable to the heat than ABS plastics are! I tried to put them straight again, but it was very difficult to do so. Also, (this is something I made mistake) I did not set the laser power high enough. This was so detrimental mistake I made that the acrylic panels did not come apart clean and neat. The panel had small acrylic parts stuck next to it. I used sandpaper to soften them up, but it was not as good as using the laser cutter. Most importantly, I did not have acrylic glue. I used plastic glue instead. Did it work?

FIg. 10. Using clamps to keep the panels tightly together [1]
I knew that something was going awfully wrong when I used these clamps. After about 15 minutes, I check if they are glued well; as I expected, the result was terrible. Thus, I threw away the material. I think I need to start over again later. Using acrylic is very important for this production.

IV. Conclusion
The problem of engraving the detailed lines on the surface of the figure has been solve. I tried to used an acrylic panel to produce cheaper and easier production of TARS. However, it was absolutely disastrous.

V. Recommendation
If I can get a glue for acrylic panel, it is probably possible to produce an acrylic TARS.

I have no intention of sharing detailed dimension or blueprint of the figure 'yet.'

Unless separately mentioned,
- [1] Hosung Won @ All rights reserved. All figures used in this post are produced by Hosung Won

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