A castle looms on the horizon, its grand pillars stretching upwards majestically. Its cascading turrets gleam as the sun sets on a full semester of successes and failures. From the top of the tower, one can see the final project glistening in the twilight’s glow.
Alright, enough with the drama. It’s finals time which, for this class, means one ultimate, last project that combines tools from various manufacturing processes. For our final project, we were tasked with milling a positive of a 3D chess piece, making a negative mold, and then casting a positive of the object and post-processing it.
My partner Tori and I began this process by browsing Thingiverse for some cool designs. Our selected chess piece was a rook, and not surprisingly we found some super creative STL files. Following a tutorial in class, we attempted to transform a 3D file into G-code in the CAD software Fusion 360. This code would act as a guide for milling for the Carvey. However, after attempting to create the G-code for a week with no progress, we realized that we would need to choose a rather simple design. We settled upon the cascading rook below.
Our selected rook model
Now I will be honest, I do not understand Fusion 360 at all. I was able to follow the tutorial from class relatively well, but Tori took the lead in creating the code. She was able to account for aspects of the milling process that I was oblivious about, and she had actual Solidworks experience which allowed her to create the keys and airholes. For more in-depth information about setting up the carve, read her blog here.
With the G-code finalized with all the necessary settings, it was simply a matter of putting the wood in the Carvey and pressing go. Because each carve took about 1.5 hours, we ended up tag-teaming a lot. One of us would stay by the machine to make sure nothing terrible happened, while the other would grab dinner or just sleep.
The Carvey in action
The final carve :’)
With our beautiful carve done, I set about preparing the mold. The silicone used for the mold came in two parts, and I mixed about 2.5 oz of both parts. I then poured the mixture into the wood to cure for 4 hours. At a reasonably late time of night, I returned to the OEDK and repeated the process for the second half of the mold. Prying the silicone from the wood took way too much effort. So for the second half I was smart enough to remember to use mold-release wax. It was still tough, but way better.
Mixing the silicone
So smooth <3
It was very sexy
The following afternoon I met up with Tori to start casting. One of the requirements for the assignment was to cast two pieces with different colors. Dr. Wettergreen never actually showed us which dye to use though, so I grabbed the only dye pots I could find in the bins by the workspace. The dye said it was to be used with “Smooth-On”. Even though we had never used that product, the instructions were easy to follow so I thought we would experiment. Equal parts of both by volume. What could go wrong? And of course, I would live to regret that question.
Unknown Smooth-On mixture with dye
Our sculpture: “The Creature from the Purple Lagoon”
Not surprisingly, the mixture turned warm after being stirred thoroughly. Surprisingly, it also began to bubble and expand. We poured it into the mold anyways, but it had a mind of its own. Within seconds we had a purple monster that refused to be tamed. Lesson learned. Stick with the products you know.
Shortly after the purple fiasco, Dr. Wettergreen appeared at the OEDK. After a short conversation we got the correct dye to use with Easy Flow and set about making our casts. The process was simple and familiar, and over the next day we made several casts of various colors. We experimented a bit with the method of mixing and pouring in order to create the best prototype with minimal air bubbles. After talking with peers, we realized that using the vacuum would be the best method for a perfect cast. However, we were multiple prototypes in and decided to focus our efforts instead on post-processing.
Our humble collection
Because I have a weird love of sanding, I took the lead in post-processing. After removing a chess piece from the mold, I used scissors and a Dremel to cut off excess material. I then used the belt sander to create an even, level bottom. Finally, I used a combination of files and sandpaper to make the sides smooth and give the appearance of a complete shape. I took special care to ensure that the grooves did not disappear, as the cascading sections were the focal point of the chess piece.
Probably the only time I will ever use this triangular, tapered file
We couldn’t get the sides to become completely uniform even after hours of sanding (I blame the Easy Flow). Yet the final rook still looks very smooth and intricate. This whole project took longer than expected with many obstacles I didn’t foresee, but it was a fun way to end a semester of prototyping. Who knows? Maybe in the future I’ll be able to repeat this process and craft my own unique chess set!
Yeah…. that probably won’t happen. But it’s nice to know that I have the skills to do it 🙂
Low quality pic, high quality piece
