Overview
ME 103: Design and Making is a Stanford mechanical engineering class where students design and manufacture their own product, developing sketches, product use-stories, rapid prototypes, 3D printed models, CAD documents, manufacturing test models, and a customer ready prototype. I created Wave, a pan-tipping assistant that makes the act of tilting a pan effortless, just like getting carried by a wave.
Pure joy radiates off my mom whenever she cooks, but as she’s getting older, her wrist feels more and more strained. For many, holding a pan is actually quite difficult, especially in one hand when the other hand is serving the food.
- Design and manufacture stand that a pan of food can rest and tilt on
- Relieve stress placed on wrist and make cooking more accessible to those with limited hand strength or wrist mobility
Patternmaking, Casting, Milling, Woodworking, Finishing
Aluminum 356, Thermal Oak Wood, Threaded Brass Inserts, Stainless Steel Machine Screws
Product Designer
10 weeks (March - June 2022)
Design Sketching, CAD Modeling, Rapid Prototyping, 3D Printing, Manufacturing
Ideation
I envisioned having two hooked stands that would support the pan, assuming the pan had two handles.
Hooked design would allow both kinds of handles to rest on top of stand while preserving rotational motion.
Experimented with different bases eg leaving middle open for plate to sit in between.
Played around with varying thicknesses and depths, resulting in intricate pattern design.
Rapid Prototyping
Cut out two stand designs from pink foam to test functionality and analyze visual appearance.
Created simple base from cardboard and assembled stands on top to see full product assembly.
Recreated mom's favorite wok out of cardboard with exact dimensions. Wok was able to easily and successfully tilt while resting on stand.
CAD Modeling
critical part quarter view
- Sketched critical part using spline tool on Fusion 360
- Extruded sketch 0.375” (half of desired width)
- Filleted and drafted all angles by 5° to get easier pull when casting
- Mirrored entire body over yz-plane to get entire critical part
Full assembly consists of wooden base and two of my critical parts. Critical parts are fastened to ends of base.
One main challenge while building my CAD model was filleting and drafting all the edges. I would constantly get error notifications, especially because there were multiple depths to my pattern.
My original approach was to create and extrude sketches on top of other extrusions to increase the thickness of certain parts, but this didn’t work as the overlaid sketches and the original would always be slightly misaligned. After much trial and error, though, I ended up creating my entire design in one sketch and then extruded each enclosed space by a unique amount.
Patternmaking
- 3D printed half of my critical part 2x with polylactic acid (PLA) so I had 2 mirrored parts of the pattern (each were 1/2 desired width)
- Felt that 3D printing double-sided pattern would ensure consistency among the two parts, especially because shape was so organic
- Included two holes for easy alignment when attaching to the patternboard
3D printed pattern (one side)
sanding down gate and runner to ensure enough draft
3D printed pattern (one side)
- Used drill and table cutter to create board out of 1” “no void” plywood
- Positioned pattern on one side and marked where to drill alignment holes
- Inserted 3/16” dowel through holes to secure other half of pattern onto other side of the board
- Cut out general shape of gate & runner with bandsaw from 1” thick scrap wood
- Drafted gate & runner with disc sander, spindle sander, and sandpaper at 10° angle
- Sanded and sealed everything with shellac to fill pores in the wood and pattern
shellac’d patternboard
Sandcasting
Each ramming session to sandcast my critical part required 100lb of sifted and mulled sand.
sifting 100lb of sand 1-2 sessions before ramming up
preparing to ram pattern on cope side of snap flask
scooping out pouring cup
pattern is rammed up and ready for metal pour
It took several tries to get a successful pull. The sand would break at the grooves, the edges where the pattern caved inwards, and near the gate and runner. To avoid the latter challenge, I could have used one runner instead of two. This would have gotten rid of the enclosed space between the pattern and gate: the part susceptible to breaking.
examples of unsuccessful pulls: common areas of sand breakage are seen in the grooves, edges, and near the gate and runner
For some of the earlier pours, the metal was very porous, indicating that the temperature needed to be hotter. It was also evident that sand broke and got into the cavities that should have only had metal. Thus, the grooves of the pattern were lost, resulting in extremely textured casted parts.
- Increased draft of the pattern by heating wax and making wax fillets around the entire pattern/grooves to pull the pattern from the sand
- Added more parting compound to board before ramming up to help with removing the pattern from the sand. This worked, but there were still some parts of sand that broke off, especially in the grooves.
- Brushed on graphite in the grooves and edges of the pattern to help remove the pattern
- Used less force when ramming up the lower layers of sand so each layer could still latch on to each other but not be so packed that the board is difficult to remove.
graphite and wax fillets added
Post-Machining
To smooth out the faces of the casted parts, I used a strap clamp setup with angle blocks to secure the casted part to the mill. I then used a shell mill tool to face off the front and back faces of the part and repositioned the clamps in between to face off the areas initially covered by the clamps.
Since the casted parts would be fastened to a base, I needed to smooth out the bottom of the stands as well. To do this, I used a level tool and the right angle block clamp setup to ensure the part was straight and then used the shell mill tool to face the bottom.
The stands would be secured to the base with fasteners, so I drilled two holes into the bottom of each part and tapped threads for 10-24 machine screws.
Woodworking
Used 0.75” thick thermal oak wood to make the base. Cut down to size with the table saw so that there was a 0.5” margin. Then used router to cut out nice design along edges.
Marked where the casted parts would align with the base according to the holes in my casted parts. Drilled corresponding holes into the base and used countersinking tool for each hole to have machine screw flushed with the wood. Then screwed in threaded inserts to fasten the machine screws.
Finishing
Since the pattern needed a lot of draft, there was excess metal around the part after casting. I used a metal file and belt sander to clean off the edges as much as possible.
I sanded the faces and edges with an orbital sander up to 600 grit. After, I transitioned to using sandpaper and sanded up to 1200 grit on a granite table for a flat work surface.
After sanding, I buffed and polished all the faces and edges so that everything had a shiny, polished finish except the grooves, which kept the casted finish.
I finished the wooden base with mineral oil since food could potentially make contact with the stand.
Final Product
Reflection
This was the first opportunity I had to design and manufacture a product of my own. Having come into the class with no prior experience in manufacturing, I was intimidated by the amount of knowledge and skill I would have to pick up, but as I spent more time in the lab, I was able to learn how to weld, machine, cast, and woodwork, becoming more comfortable with the various tools, machines, and manufacturing processes.
I also learned the importance of iteration and troubleshooting. Failure was inevitable during this process, but working through these challenges provided me constant opportunities to discover, problem solve, and brainstorm various solutions. This project has left me with a valuable set of personal skills and an impressive knowledge of new manufacturing and design skills.
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