Week 1 - Journal

This week we were required to find a 3D model of our choice in any opensource CAD library as long as it can be downloaded in an STL format, consists of a single piece model (no mechanisms or complicated shapes) and can be printed in under 90 minutes. At first, I tried looking for a cat toy but the single piece toys were not interesting (well, at least won't be interesting to my high-maintenance cat). Eventually, I found this funny 'Cat stand' desk piece that looks like a cat and can be coloured after printing. 

We were also required to find a 2D model of our choice in any opensource CAD library that is or can be converted to DXF format, also consisting of a single piece model (no mechanisms or complicated shapes). Following with the cat theme, I found this cute and cartoonish 'Cat medal' that I reminds me of my cat, Yushi.

• Ultimaker Cura for slicing the STL file 

• Prusa i3 Mk3 machine for printing 

• PLA filament for printing

• Cloudconvert.com to convert the file from cdr to dxf format

• LaserWork 6 for preparing the file to be laser cut.

• Plywood sheet to execute the medal design

To avoid exceeding the print time (as well as using more grams than necessary), I started adjusting parameters like the print speed readjusted back to 60 mm/s (instead of 30 mm/s as recommended by the piece's designer). This resulted in a model of 10 gms and the print time to be reduced to 75 minutes. The file was saved in Gcode format and renamed with details like the layer height, print time, grams, and filament colour.

For the laser-cut task, I came across the 'Cat medal'. As you can see, the file is in CDR format. I used www.cloudconverter.com to convert it into a DXF format to import it on LaserWork 6 and prepare it for cutting. Upon selecting the file and before importing it on LaserWork, a preview is shown so the user is certain they're choosing the correct file.

After that, I started selecting different lines and assigning them by colour to different actions/outputs; Black for cut, red for scan, and blue for speed cut. Then, I changed the powers and speed for each action/output to match with that of the Laser cutting machine as shown in the note in the lab.

Finally, after reviewing the lines and the actions/outputs they're assigned to for one last time, the file is saved and exported to plt to be compatible with the Laser cutting machine in the lab.  It was also important to name the file accurately with the dimensions to make it easier when selecting the sheet size for cutting and also for its placement.

Starting with the laser cutting, I had the machine's instructions manual opened on my laptop to follow its steps. I opened the machine and the technician reminded me to also turn on the exhaust fan. After that, I transported my file to the computer linked to the machine. I also double checked that I had the right speed and power types and that I had the 'Path optimize' checked before saving. The technician also asked me to rename the file. I noticed that the file name had to be very short to be accepted.

The technician handed me a plywood sheet to be used for the laser cutting. After placing it on the machine's work surface, I added the wooden hinges used to fix the sheet in its place as any movement while the machine is working will negatively affect the outcome's quality. I then closed the machine's lid. Heading back to the machine's screen, I chose the file, selected frame to see where the machine's tube would start, moved the tube until it was in the far right corner of the sheet, clicked frame again and once I was satisfied with the placement. I clicked pulse just to make sure everything was fine.

The 3D printing process was less hectic. First, the technician instructed me to preheat the printer's bed. The control knob was quite funny as it rotated in opposition to the direction of scrolling on the screen. After selecting Preheat, the screen lists down the different types of filaments it can work on. PLA was selected and as shown, the temperature of both the nozzle and bed gradually started increasing. Next, we inserted the SD card. Before choosing the file, we had to go back in the list and select Unload filament to remove the existing one  as I wanted to use a different colour.

The screen instructed in to pull out the filament. I learned that it was a time sensitive process and that you have to act quickly. After that, I used a wire clipper to cut the tip of the new filament  to make it thin and easier when inserting it into the nozzle after mounting it onto the machine. Going back to the screen, I selected load filament and inserted its tip into the nozzle's top opening. Nothing came out and the screen asked for confirmation that the correct colour was extruding from the machine. As nothing came out, I selected 'No' and the machine tried again, extruding the filament this time.

Finally, we're all set to start printing the model. Following the steps on the screen, I selected 'Print from SD' > 'PLA 215/60'. The screen shows that everything is okay. I clicked the start button again and it took me back to the first list. I selected 'Print from SD' then chose my file. A short loading screen appeared then it showed the details of the printing process. I closed the enclosure door panels of the printer to preserve the heat during the printing process. The machine started the process by calibrating the space (bed) onto which it will print; similar to the framing action in the laser cutting machine.

And now it was all up to the machine to do its magic! I only had to check every once in a while to make sure that the model was coming out as expected and that in case anything would go wrong, I can stop the printing process. 

Please enjoy this timelapse of 75 minutes print time! 

When preparing the file, I noticed that the design was mirrored and when I asked the technician, she suggested that it could be due to different formats between the program we use to prepare the file and the one linked to the machine but since it did not really affect the outcome needed, I decided to ignore it and continue working. 

As for the issue of the over-burnt area. The technician ran a simulation of laser cut process on the computer and found that there is a double line that was not visible. However, even after removing the double line and giving it a second shot to produce a better piece. The problem persisted and this time the technician stated that it could be an issue with the source file and that it needed further revision later.

For future reference, I would try to make sure there are no double lines and use the simulation function in Laser Work to help me make sure there are no unpleasant surprises in my files.

After the printing process was done, I was a bit hesitant while trying to remove the model with the bed scrapper as I was worried it might damage the model in the process. The technician reassured me and showed me than even with a little bit more force, it was still sturdy enough. Another thing was the supports. The brim peeled off easily as it was thin but I had to be extra careful while removing the supports with a clipper so as not to damage the face and paws of the model. 

First, by better understanding the different usages of each software and machine, I will be able to determine how to generate and fabricate the different physical parts of my project. The laser cutting machine could produce certain parts of my products packaging (like a box or a container). While the 3D printer could produce more complex parts like connections or hinges.  Given that the final project is a monitor installed on the Butane gas cylinder usually found in kitchens. It needs to be made of a durable, heat resistant and water resistant material.

This means that I would probably rely more on plastics and therefore, I would probably rely more on 3D printing than on laser cutting sheets of wood or acrylic. Since the project is leaning more towards being functional than being aesthetic, I would probably reduce the layer height but increase the infill so that the parts are more sturdy and durable. When printing this model for example, I had to balance between having a nice looking desk piece but also heavy enough so it wouldn't tip off easily when a pen or an accessory is placed on top as shown in the photo.

During this week, we had our site visit to Jet Solar Factory. While my project is not really related to solar energy. I enjoyed the tour found it quite impressive. Since I intend to have my project to be 'hopefully' mass-produced, it is quite important to know who to optimize the production process in terms of resources like raw materials, energy consumption and the individuls involved in production. Quality check is also important to ensure that the end users don't have to deal with faulty products. It would also cost the producer more money (and impact reputation) to collect faulty products and fix them after distribution