# Week 1 ## Individual Assignment: Vinyl cut something THE formative experience that led me to apply to graduate programs in particle physics took place at Fermi National Accelerator Laboratory (FNAL, or Fermilab) in Batavia, IL, where I attended the Compact Muon Solenoid Data Analysis School in January 2017. We learned the process of particle physics data analysis in an intensive, hands-on, one week session. To me it was the very peak of a process of falling in love with experimental work, and of re-centering hands-on learning in my life. Naturally, the first thing I thought of for a vinyl sticker with which to decorate my laptop was Fermilab's brilliant logo. It's a simple design consisting of overlaid schematics of a dipole (looks like an equal sign) and quadrupole magnet, the essential tools of the accelerator physicist. Dipole magnets are used in particle accelerators to steer particle beams, and quadrupole magnets are used to focus and defocus the beam. Although I had a difficult time weeding the unwanted material off the sticker, and ended up with slightly ragged edges at the tips of the quadrupole (I'll try setting the force a little higher in the future), I'm very happy with the result and with the elegant addition to my laptop decor. <img class="centering resize-tall" src="resources/fnal_sticker.jpg" /> Fig. 1: Vinyl-cut Fermilab logo sticker ## Group Assignment: Characterize the kerf of your laser cutter The kerf of a laser cutter characterizes the amount of material the laser destroys/removes, and is usually given as a length indicating the effective radius of the beam. Our group developed a few similar methods for determining the kerf of our cutter, and we each cut a test piece and performed a measurement, gathering six different measurements and then averaging over them to get something that's hopefully accurate. My method was to cut out a spar on a piece of cardboard which I specified to be 10 mm wide in CAD, and then to measure the actual width of the spar using calipers (pictured below). The effective radius of the beam would then be half the difference between the actual width of the spar and 10 mm. Other members of the group used a similar method but involving measuring a slit or notch (negative space) instead of a spar. <img class="centering resize-wide" src="resources/calipers.jpg" /> Fig. 2: Measuring the spar with calipers We gathered six data points total, and upon averaging them arrived at an estimate of the kerf of 0.31 +/- 0.03 mm (stat.). <img class="centering resize-wide" src="resources/kerf_meas.jpg" /> Fig. 3: The data points for our group's kerf measurements, along with our test pieces We each also created some test pieces with slots that varied in width down to a hundredth of a mm, in order to determine which slot size, when convolved with the laser cutter kerf, would yield the most structurally sound fit for our construction kits (pictured around the measurements, below). For my kit, I ultimately chose to use a slot size of 3.6 mm, which when cut on the line resulted in an actual slot size of about 4.2 mm. <img class="centering resize-wide" src="resources/comb1.jpg" /> Fig. 4: The two comb pieces I cut in order to determine the best slot size ## Individual Assignment: Design and laser cut a press fit construction kit For my construction kit I chose to create a simple set of slotted squares, experimenting with the filleting feature in FreeCAD to create curved slot entrances for easier assembly. In my initial attempt I used a smaller specified slot size (3.55 mm), which I found did not work well for assembly (fig. 5). I was also not happy with the exaggerated fillets at the slot entrances, and wanted to make them a little more subtle while still retaining the function. <img class="centering resize-wide" src="resources/failed_design.jpg" /> Fig. 5: Initial attempt where I didn't like the slot size I reduced the radius of curvature of the fillets, widened the slots to a specified size of 3.6 mm, and reduced the length of the slots to make it easier to fit multiple pieces together on the same "base" piece. I was much happier with these, and despite their simple design it was oddly satisfying to assemble them into various <img class="centering resize-wide" src="resources/final_design.jpg" /> Fig. 6: The final design after making some changes <img class="centering resize-wide" src="resources/comparison.jpg" /> Fig. 7: Comparison of the initial and final designs <img class="centering resize-wide" src="resources/cubestand.jpg" /> Fig. 8: A box with standoffs <img class="centering resize-wide" src="resources/space_invader.jpg" /> Fig. 9: A space invader-like figure <img class="centering resize-wide" src="resources/arthurs_creations.jpg" /> Fig. 10: The results from a few minutes of my friends messing around with the squares I liked the space invader figure a lot, and now I'm thinking about augmenting the set to make it easier to create pixel art-like sculptures. Another possible direction would be improving the ability to make boxes/shelves with it, although I don't think those would be structurally sound enough for anything other than... maybe other small lasercut things? <hr/> [Home](../index.html)