Master Chef Scabbard

CAD model of the “Master Chef Scabbard”


While my initial brainstorming sessions focused on developing gifts for others, I eventually decided to design a gift for myself. Since I gravitated toward ideas related to lighting and video games, I eventually settled on creating a Legend of Zelda themed lamp, which would involve Link’s glowing master sword. However, after experiencing several hardware issues during week 8 of my mechatronics course, I decided that I would be much happier creating something that did not involve circuitry.

After more lateral thinking, I finally generated an idea that really excited me: a sheath for a chef’s knife based on the master sword sheath from Legend of Zelda: Twilight Princess. My goal for the “master chef scabbard” was to spark joy in my daily life by transforming myself into a hero every time I chopped celery and diced onions. I lasercut a duron model of my vision to finalize sizing and detailing decisions before proceeding with CAD and CAM design.


  • ⅜″ x 3″ x 3″ Brass
  • ¼” x5.5” x 3’ Walnut board
  • 3″ Shell Mill
  • ⅛” and ¼” Flat End Mill
  • ⅛” Ball End Mill
  • ¼” Drill
(Intended) PROCESS
CNC machining process: Brass
  1.  Square brass stock using a manual mill
  2. On Haas CNC, perform facing operation to mill stock to required thickness
  3. Perform adaptive clearing operation to reveal triangles, down to 0.1″ above model bottom
  4. Scallop all chamfers
  5. Perform another adaptive clearing operation, leaving a thin web of 0.005″
  6. Separate each triangle using band saw and files
  7. Finish parts using sand paper and polish


CNC machining process: Wood
  1.  Plane walnut board and saw into two 16″ pieces
  2. On ShopBot, perform pocket clearing operation for knife slot
  3. Drill holes for alignment dowels
  4. Part flip!
  5. Perform adaptive clearing operation to rough out detailing, down to 0.1″ above model bottom
  6. Scallop all curves and fillets
  7. Perform another adaptive clearing operation to remove excess material
  8. Separate part from tabs using band saw
  9. Repeat steps 2-8 for other half of the sheath
  10. Use wood glue and dowels to fasten both halves of the sheath together
  11. Finish wooden sheath using sand paper and mineral oil
  12. Attach brass triangles to sheath using epoxy


Although the COVID-19 outbreak restricted our use of the CNC during week 10, I was able to think laterally, refine my CAD models, and dedicate time toward grasping CAM software. Overall, I had a great time learning about machining, tooling, workholding, lateral thinking, and communication.

If I could redo this project, I would explore alternative ways of fastening my wooden and brass parts. I would also redesign the sheath such that only one half had a knife-shaped cut-out while the other half was completely flat. Then, my project would only require a single part flip rather than two part flips, which would reduce my risk of misalignment. On the bright side, since the PRL won’t reopen for another few weeks, I have plenty of time to continue laterally thinking and improving my CAD and CAM files before I actually manufacture this project. Thank you to Craig and Taylore for their guidance throughout this quarter!

Exploded view of entire assembly


Design Process

My bottle opener is inspired by F. Scott Fitzgerald. He is most famously known for The Great Gatsby, which was my favorite assigned reading from high schoolMy initial brainstorming ranged from an elegant brass letter opener to a glowing green ring. However, upon chatting with Craig, I realized I had fallen into the trap of vertical thinking. My initial designs focused on showcasing The Great Gatsby through obvious symbols such as art deco and the green light rather than tackling more abstract ideas. Thus, I challenged myself to revisit the drawing board and think more laterally.

My final design was a bottle opener that symbolized the life of the main character, Mr. Gatsby. He was born into a poor family in rural North Dakota as James Gatz. Upon meeting tycoon Dan Cody, he decided to change his name to Jay Gatsby and pursue a more lavish and extravagant lifestyle. In his pursuit of the “American Dream”, he hid behind many personas (such as being an Oxford man) to fit in with the old money elites. Only a few people (namely Gatsby, Nick Carraway, and the reader) know of the real Gatsby.


To illustrate this, I designed my bottle opener such that it starts with a simple, cube-like shape that morphs into a series of complex curved surfaces that each display a distorted reflection. When a user opens the bottle (with their right hand), they see their own “true reflection” on the flat side of the opener, while surrounding guests see the warped reflection on the other side of the bottle opener. Similar to Gatsby’s origin as James Gatz, the bottle opener itself is made out of a humble material, aluminum, but is polished to appear more impressive.

Manufacturing Process


    • 1″ x 3″ x 6″ Aluminum
    • 3″ Shell Mill
    • ¼” Flat End Mill
    • ⅛” Ball End Mill
    1. Square stock using a manual mill
    2. On Haas CNC, perform a facing operation to mill stock to required thickness
    3. Perform an adaptive cutting operation to map out the upper curved surface
    4. Contour the boundary down to 0.1″ above the model bottom
    5. Scallop all curves and fillets
    6. Contour the boundary until there is a 0.010″ web at the bottom of the part
    7. Remove the web using a band saw, vice grips, and files
    8. Finish the part using sand paper and polish

I edited my CAM file right before plugging it into the CNC. Unfortunately, I did not catch that the wrong tool was being used for my final operation, hence the large scratch that was left by the tool holder. Luckily, I was able to sand it out, but much frustration could have been avoided by triple checking my setup sheet and staying calm throughout the process.

I also learned that finding all of the tools (and updating the CAM file to match) takes a lot more time than expected. In the future, I hope to organize my tools in advance during an earlier shop session, so that I can more efficiently utilize my CNC time slot.

Cheers, old sport!