The Mahaba Mini Table
Check out the full presentation here!
Processess:
Woodworking, Casting, Lathe, and Mill
Classification:
Physical Design + Manufacturing
Timeline:
8 weeks
Background
This project was for one of my Product Design classes at Stanford. Students were required to create a product using two common manufacturing processes available to mechanical engineers.
Inspired by Japanese design and woodworking techniques, I embarked on the creation of a miniature tea table. I crafted this project using a combination of walnut wood, aluminum, and copper rods to achieve the desired aesthetic and functionality.
Solution
The Process!
We kickstart the process with the ideation stage! At the beginning, my mind was buzzing with countless grand ideas about what I wanted to create. I went from envisioning crafting a cooking knife as a food enthusiast to sketching up concepts for an owl lamp. However, I soon realized the complexity and challenges associated with these projects. As I delved deeper into understanding the manufacturing processes and their limitations, I took some time for introspection to refine my creative direction.
During this introspective journey, I zeroed in on the ideation stage and decided to merge my passion for food and tea with the creation of furniture. That's when I settled on the concept of my miniature tea table, a project that would encapsulate my creative vision and practicality:)
Rapid Prototyping
Being a visual learner, I immediately delved into the prototyping phase, making use of available scrap materials. Fortunately, I stumbled upon leftover metals and wood in our student lab, providing me with the opportunity to familiarize myself with the organic shape of the wooden top and the aluminum legs. This initial stage proved to be a positive learning experience, as it allowed me to make numerous mistakes, each serving as a valuable lesson before I ventured into working with the final materials.
The purpose of this prototype was to test the structural concept and overall viability of the process. During this hands-on phase, I realized that the intricate contours of the wooden top demanded extra attention and precision during the sanding and shaping processes in the wood shop. Furthermore, I encountered challenges in dealing with the curvature and design of my table legs when attempting to cast and mold them in aluminum. This process was instrumental in helping me identify potential hurdles in the manufacturing process. With these lessons in mind, I delved deeply into the manufacturing phase of the project!
Scrap wood used to test the shaping process
3D printed table leg mold for aluminum casting
Aluminum rods that required troubleshooting due to uneven holes
Before starting the project, our course introduced us to casting through the creation of a bronze bell. Following a lab session in our school's foundry, I left with the assumption that casting would be a straightforward step within the overall manufacturing process and eagerly included it in the project's required list of processes. However, upon designing my table leg, I quickly realized that I severely underestimated the complexities of casting a custom part. The journey was filled with numerous failures as I gradually changed the design to meet the specific needs of the casting process.
Casting
With the guidance of the class's course assistants and the lessons learned from my casting failures, I came to the realization that the challenges I experienced came from a couple of issues:
Low infill. The 3D printed models that were designed for casting had a really low infill percentage, ranging between 5-10%. Such a low infill resulted in the models buckling under the pressure of densely packed sand. This led to cracks in the molds, thereby preventing me from having a successful pour.
Narrow gate and runner. In my initial design, I noticed that the gate and runner were quite slender, which posed a challenge for an effective pour. It became clear that enlarging these components and adjusting their angle was necessary to facilitate a smoother and more efficient flow of molten aluminum.
Too much ram force. When ramming up, I simply used too much force on the packed sand. This, to my surprise, led to cracks!
Luckily, after a lot of trial and error and some redesigning, I finally got both aluminum legs right. It took way more time than I thought it would, but it was totally worth it in the end. I trimmed down the gate and runner and started the long job of sanding the legs until they were really smooth and shiny.
Machining
After cutting off the gate and runner, the next step was to mill off the extra angle from the aluminum legs. To make a good mold for casting, the 3D printed model of the leg needed a 10-degree draft on both sides of the part. This extra material had to be removed to get a flat surface for joining the metal legs with the wooden top. Once I had a flat surface, I drilled and threaded four holes in the aluminum for the 1/4-inch screws for assembly. The copper rods aren't in the picture, but they were shaped on the lathe to have a tapered angle, adding a nice touch to the look.
Sheet metal work
Now onto sheet metal! For this part of the project, I had to get creative in figuring out how to make handles and join aluminum with wood. For the mini-table's design, I wanted copper rod handles to create a clean, minimalist look that echoes Japanese styles. It was tricky at first to figure out how to shape the rods since they were too small for tube bending, but then I realized they were just the right size to shape by hammering.
The second part of working with sheet metal involved the piece that would sit atop the aluminum legs. I found that the best way to join metal with wood was to use a sheet metal intermediary, which allows for screws to bind them together. I shaped this sheet metal using a sanding machine and punched holes in it to align with the screw holes on the aluminum legs. There are four screws on the outside of the aluminum legs that attach the sheet metal to the wood, and another four screws that connect the sheet metal to the aluminum. This method ensures all parts are securely stabilized through the sheet metal.
Woodworking
Last but definitely not least, woodworking! I began with a piece of scrap walnut wood, shaping it with a bandsaw and a machine sander. After that, I drilled four holes on the side of the wood for the handlebars, which I planned to glue in later. This was tricky because the organic shape made it hard to keep the wood stable for drilling. But, after a lot of thinking and some trial and error, I managed to drill holes deep enough for the copper rods.
Then, I moved on to drilling half-inch holes in the bottom of the wood base. These were for the heads of the screws that connect to the aluminum legs and sheet metal. By having these holes in the wood, the table top and legs can sit flush against each other, ensuring a seamless and attractive attachment.
To wrap it all up, I finished with sanding and applied four layers of semi-gloss polyurethane. This really brought out the stunning color of the walnut wood.
After all of the processes were done, I finished everything up with a simple assembly. Check out my hero shot!
Greatest Takeaways
Intentionality is key. The failures I experienced during the project taught me that I must constantly question every step of my process. The whys, hows, and whats are extremely important for smooth, trouble-free execution.
Plan ahead! Given the tight deadline for the project, sticking to a strict schedule was key to my success. I'm really glad I planned ahead and set my own milestones ahead of the class schedule. This allowed me extra time to troubleshoot any issues that came up and also focus on the finer details of the project.
Research manufacturing processes for a greater understanding of the potential challenges that could arise. Since I only learned all the manufacturing processes like machining, casting, and woodworking two weeks before starting this project, in hindsight, more research beforehand would have been incredibly beneficial. It likely would have saved me a significant amount of time during the project.
Thank You!