Laser Cut - 3D Pentagonal Prism

For this making assignment, I designed and fabricated a pentagonal (5-sided) prism using Fusion 360 and the laser cutter. My initial goal for this project was to familiarize myself with geometry shapes in both 2D and 3D. More specifically, I aimed to practice translating a designed 2D net into a 3D sign while ensuring that the design is correctly parameterized. For my design, I chose the pentagonal prism because it is visually more interesting than a simple cube and pyramid but still manageable and beginner-friendly in terms of 2D net design on Fusion. In addition, I also designed glue tabs for my fabricated object, so I can put the glue on those tabs and distinguish those glued tabs with actual shapes through fold lines. This decision enabled me to think deeply about the importance of tabs in transforming flat designs into solid forms.

1. Fusion 360
2. Inkscape
3. Laser Cutter (Library Makerspace)
4. Cardstock (Library Makerspace Locker)
5. X-acto Knife & Ruler (for hand scoring fold lines)
6. Glue

Once again, I decided to go with a pentagonal prism since it allowed me to experiment with non-square edges, closures, and fold accuracy.

First, I began to start with a simple but parameterized sketch of a pentagonal prism on my iPad. The pentagonal prism has 5 flat and lateral rectangular faces and also requires two identical pentagon bases. I annotated the width of the faces to be 5 inches and their height 2 inches. And I also made sure that the 5 sides of the pentagon are all equal in length and also equal to the height of the rectangular faces.

I also distinguished the design for the glue tabs in orange; the tabs are trapezoidal. The biggest tab is for the bases of the geometry, and the smaller ones are for the faces.

Through entering Sketch mode, I drew 5 simple rectangles, making sure that their height and width follow my established parameters. I drew a pentagon and defined the side length as the parameter "height" of the rectangular faces. Then, I drew all the tabs on the left side, ensuring that their sizes are equivalent. Then, I conducted mirroring by drawing a line in the middle and mirroring the pentagon and the tabs to the other side to make sure all the pentagons and tabs are the same. After that, I extruded the whole body with a distance of 1 mm to add dimension to the 2D prism net.

Secondly, I swapped into the Manufacture workspace to get the laser-cut tool. For the Work Coordinate System (WCS), I chose "Z axis/plane & X axis" for orientation and clarified that the Z axis was for faces and the X axis was for the edges. I also changed the mode to relative size box and selected the face that I wished to cut out for face contours.

Everything went well, as there was no orange/red icon with a warning appearing. Then, I proceeded to save the file as an Autodesk | AutoCAD DXF file into my personal directory.

Using Inkscape, I transformed the DXF file into an SVG file and exported it. You can see that the cut lines are in red.

I sent the SVG file to the laser cutter using cardstock settings. I encountered a problem where my 2D net was too big and out of scale for the laser cutter. What I had to do was to scale the shape down so it could fit on the cardstock so the laser could cut through the whole entire shape. The first round of cutting took around 13 seconds. However, after the first attempt, the laser did not cut through the cardstock. Therefore, I proceeded to cut the 2D net one more time. The fabrication process went smoothly.

Since I did not do the lines for engraving, I used the X-Acto knife and a ruler to hand score the fold lines. This allowed me to easily fold along the lines without destroying the original shape of the geometry I wished to achieve. I, then, folded along the hand-scored lines. Then, I used glue on the inside tabs that I designed to create invisible seams. Lastly, I started by attaching the lateral rectangles into a strip then glued the bases last, while ensuring that all the tabs and glue lie inside of the 3D pentagonal prism.

The final form was a closed pentagonal prism with clean edges and no visible tape outside of the form. The folded lines gave it a professional and aesthetic appearance. However, the assembly was trickier than expected, as getting the corners to line up and waiting for the glue to dry took up some patience.

I was pleased with the crisp folds and overall sturdiness of my form. However, if given the chance to complete this project again, I'd add locking tabs (with slits) instead of glued tabs for cleaner closure and more professional outcome.

The assigned reading—Structural Packaging: Design Your Own Boxes and 3D Forms—gave me some valuable insights in shaping my net designing.

The first section on "How to Design the Perfect Net" highlighted the importance of accuracy in parameterization for clean and professional shared edge lengths. When sketching my net design on Fusion, I carefully planned and parameterized my widths and heights of my desired shape. Specifically, I made sure that the pentagon's side matched with the rectangular bases' height to avoid any mismatches in my final outcome.

The second section on "Common Closures" taught me the importance of locking mechanisms, as these locking tabs and other forms of joinery played a critical role in making our 3D geometries seamless and professional. This section influenced me to do simple invisible glue tabs. These tabs, though, still required glue for final execution. However, I also thought about experimenting with more complex locking mechanisms in the future.

The last section on "Creating with the System" offered some very interesting yet complicated inspirations for this making assignment. It inspired me to do something a little bit more complex than simple cubes and pyramids, but still making sure that the shape is still manageable. This made me realize how nets can scale in creativity without necessarily scaling in difficulty, if carefully parameterized.

Ultimately, this reading enabled to gain deeper understanding on the interaction between 2D and 3D design.