FLOATING STEPS
Tools & Skills: physical product realization, CAD in Fusion 360, lathe, mill, laser cutter
Project Brief
Design and manufacture a device, sculpture, or tool that is significant to you (or to someone else). The final product must be made of metal or plastic and must be made and finished using a combination of processes in the Product Realization Lab (PRL)’s machine shop.
Challenges
Budget restrictions combined with the cost of materials didn’t allow for any trial and error in making my critical parts. Additionally, because the machinery in the PRL is hand-operated, it often required more time than expected to make sure my set up was as precise as humanly possible.
Results
I was initially concerned that my project would be too simple since it only incorporated two processes, but it was actually perfectly scoped for the allotted budget and time. I was able to achieve what I’d designed in terms of appearance and functionality — an easily deconstruct-able, “magical” table top display!
CONCEPT SKETCHES
I wanted to use this project as an opportunity to make something that displays small plants in a unique way. I also wanted to be able to freely assemble and dismantle the final product for easy storage and transport. I ultimately landed on this “revolving terrarium stack” concept that consists of a metal base, a metal pole that can be screwed into and out of the base, and terrariums that can be stacked onto and rotated about the pole.
CAD ASSEMBLY
Initially, I was thinking of making the terrariums out of pieces of glass that were soldered or welded together. However, I was advised against this, as adhering different materials to each other is not an easy process, and glass is not a very PRL-friendly material. This pivot provided me with the opportunity to make my design “more magical,” in that I could make the terrariums completely transparent to make their contents appear as though they are floating. I decided to take this a step further and make the terrariums themselves appear as though they are floating as well by making the center pole “stepped.”
Turning down the pole on the lathe: If the pole were designed to have steps that were either only increasing or decreasing in diameter along its length, it would have been more straightforward to turn down on the lathe. However, since the steps were both increasing and decreasing in diameter, I had to reorient the part several times. Using what became fondly known as the “rotisserie” method, I live-centered the part, turned down its stepped diameters, and threaded the bottom end on the lathe to create the center pole.
PROCESS PHOTOS
The two main PRL processes I chose were the lathe and the mill. Because my design required shapes that are atypical for their respective processes, I had to take extra steps to set up and machine my critical parts. The materials I decided to use were aluminum — a softer, easily-to-machine metal — for the base and pole and laser-cut acrylic (plastic) for the terrariums.
Machining the base on the mill: The mill is typically used to machine out material along linear paths. In order to machine out circular shapes, I had to use the rotary table attachment. Unfortunately, the digital position indicator on the mill does not apply to the rotary table, so centering the base was quite challenging. However, once I was able to find the center, I machined the edge of the base to get a smooth finish, milled out a channel using a ball-end tool, and threaded the center hole using a tap.
Assembling the terrariums: I used the laser cutter to cut out the panels for the terrarium boxes from acrylic sheets. I wanted the top face to slide open and closed like a drawer, so I milled out tracks in the inside faces of the side panels. I sealed the panels together using acrylic cement (minus the top face) to create the terrarium boxes.
Finishing and final assembly: I wanted a mirror finish on my critical parts, which required a lot of sanding. To finish the base, I used an orbital sander, and I sanded the pole on the lathe. Upon testing the assembly, I was so excited to see that the threads worked and the pole could be easily screwed in and out of the base and that the terrarium boxes rested properly on the pole!
FINAL PRODUCT
I realized that I could create differently shaped shelves and containers in addition to the terrarium boxes, allowing me to display plants, small items, or a mix of the two! Overall, this project fulfilled all of its design goals, and I’m really happy with the final product.
