Assignment 5

Electronics Production

The group task for this week's assignment was to characterize our small cnc milling machine for a PCB production process which can be found here. For the individual task we had to make an in-circuit programmer by milling the PCB and program it, so that we can use it to program our board in Electronics Design week, and in other weeks. Below is the description of my process:

Making PCB:

1. For the laser cutting assignment I wanted to design a rocket that could be assembled into a floor lamp. After starting I discovered that there are already examples of such kits out there, but I wanted to design my own shape. For that I found a silhouette of a rocket from here and used it as a base in Fusion 360 to develop a press-fit kit for that shape. I imported the image by using "Insert" command from the menu and chose a surface on which I wanted to place it.

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2. After importing the image I started a new sketch and traced half of the silhouette with a "spline" command to create primary ribs with a leg for the rocket. The splines needed to be parametric so that, if needed, the size of the rocket could be changed easily. Setting the parameters and constraints was a lengthy process because of the organic shape of the rib. In order to keep all the lines proportional to rocket's height all the control points on splines had to be separately constrained and defined by a parameter.

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3. One of the problems I had was with the "offset" command. It appeared that after using the command it was not possible to edit it without loosing the offset constraints. For example, on the picture below, I wanted to cut off the tip of the rib vertically after offsetting, so that multiple ribs would fit together at the top. But after "trim" command the offset constraint disappeared. At the end I decided to set an extra line instead of trimming, so that the editing could be done after importing the file into Illustrator.

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4. It took many trials and errors to arrive to a successful paramteric design for the rib. On the picture below the height of the rocket is changed from 110 mm to 220 mm with all the lines scaled correctly.

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5. From the drawn rib I extracted the secondary rib (right on the image below) with propulsion part and without a leg to go in between the four ribs with legs (left on the image below). In addition, I defined the positions and radii for the horizontal circular parts on the ribs which would connect the ribs into a rocket shape.

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6. When constructing the circles I wanted to define the constraints and paramteres for the circle diameter, slot width and depth, so that these could be changed when rocket size, cardboard thickness or rib size respectivly should change. However, here too the "offset" command caused me a lot of same troubles, because I wanted the slots to be cut out in Fusion 360 and not in Illustrator to minimize editing due to a high number of circular parts. I also tried using orthagonal construction lines inside the slots to define the size of them, but with no luck. Due to time limitation I was not able to model the slots on the circles parametically and I continued editing them manually.

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7. Due to time limitation I was not able to model the slots on the circles parametically and I continued editing them manually. I copy-pasted 21 circles, changed their diameters according to the radii defined on the ribs and cut out the slots.

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8. In the lab I wanted to cut some test parts with the laser to see whether the 3 mm cardboard would fit into the slots I constructed. I soon realized that the 3 mm wide slot would be too wide due to laser's kerf and constructed too circles with 2 mm and 1 mm slot widths as a test. I also tried cutting test parts for the ribs changing the direction on the cardboard to see which direction would make the strongest parts. I found out that the 2 mm slot width worked the best, and that the ribs have to be cut out perpendicular to the cardboard's corrugation.

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9. After cutting the test parts I proceeded with changing the slot sizes on the circles to 2 mm. As the circles where not drawn parametrically this took a lot of time. In addition, I kept having problems with the speed of Fusion 360. For some reason, even after restarting and opening a separate file for the circles, it was very slow increasing the drawing time even more.

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10. After editing I had 18 circular parts for the main body of the rocket and 3 parts for the propulsion, all with different diameters.

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11. When I was done in Fusion 360 I saved the file as a dxf and imported it to Illustrator through "File" > "Place" command. It was important to check that the imported file will keep its original size and that the units match with the ones I worked with in Fusion 360.

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12. The Illustrator file was then trasferred to the computer of the laser cutter. I opened the software of the cutter and imported the ai file through "File" > "Import" command. I placed my parts in the up left corner and copy-pasted 11 ribs, as one was cut out during testin already. I tried to place the parts close to each other to not to waste the material. By double clicking on the black colour on the up right menu I could edit the settings of cutting. I set the speed of the laser to 150 and power to 90. By pressing "Download" I could send the file to the laser cutting machine. However, I got an error shown on the image below. I realized that the laser machine was not turned on which is why the computer could not send the file to the machine.

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13. Before cutting I also checked the height of the laser from the cardboard with a wooden tool provided by the lab, and placed the laser head with the arrow keys to the right place on the cardboard for cutting. I also pressed "Test" on the laser machine to check whether the area which is need for cutting will fit where I set the starting point of the laser head. After playing around with these settings I found a suitable position for the laser and started the cutting job by pressing "Start" and turning on the filter.

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14. After cutting the parts I assembled the rocket. It turned out to be a bit difficult job due to the weakness of the material. Because I needed to set some force to click them together the parts morfed and the outer linerboards of the carboard came loose in some places. All in all, I am quite happy with the final result for the first try. However, there are a number of things to be improved for the next time: 1. The circular parts have to be drawn parametrically so that their size can be changed easily, 2. The ribs have to have slots for the circular parts to be clicked in so that their position can be fixed and the connections would be stronger, 3. The number of circular parts have to be reduced as 21 one was too many, 4. The slots have to have cut off corners so that the part would click into each other with less force.

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1. For the vinyl cutting task I found an image of an ant here and opened it in Illustrator.

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3. Lorem ipsum dolor sit amet, brute laudem urbanitas qui cu. Vis at esse atomorum, ius movet noluisse in. Cum mucius virtute te, id wisi aliquam legimus eos, pri at saperet reprehendunt. Electram intellegebat quo id, mei mazim sanctus verterem at. Duis nullam equidem ne mei.

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4. Lorem ipsum dolor sit amet, brute laudem urbanitas qui cu. Vis at esse atomorum, ius movet noluisse in. Cum mucius virtute te, id wisi aliquam legimus eos, pri at saperet reprehendunt. Electram intellegebat quo id, mei mazim sanctus verterem at. Duis nullam equidem ne mei.

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