When we found a 3D-print design of a Smiski doing a headstand, we knew we had stumbled upon what we wanted to make for this project.
Gate 1
For gate 1, we found a file on MakerWorld which is the Bambu community shared files.
File link: Headstand Smiski by nathan32 MakerWorld: Download Free 3D Models
We then uploaded the file to Bambu studio to 3D print. We printed several iterations of the smiski scaled to different sizes to see which one we would like most to use. We ended up using the largest size which was scaled 400% more than the original file. We printed the smiski using white PLA.
Gate 2
For Gate 2, we had to create the positive part of the mold, but 3D printed. We had some issues splitting the model in two since the model was a mesh part in Solidworks instead of a full model. We had to estimate where the center of the object was and split it accordingly. We decided to use the side with the face for the 3D printed part of the mold so that it would produce a more accurate design and as a result a more accurate mold.
Once we had the face half of the smiski, we constructed a rectangular stand around him and added circular holes to hold the mold together and a pour hole where we could pour our formula to create our final chess pieces.
Once our file was ready, we sliced it and 3D printed the part. When we first printed the part, we laid our smiski flat on its back and this caused for not that accurate of a print due to the way it printed its layers.
Now that we had the positive part of the mold, we had to create the silicone negative counterpart. We first created a box of indeterminate size made of cardboard around the 3D rectangle. We used hot glue to ensure that the box was sealed tightly around the half smiski piece. We then created our silicone mixture that was one-to-one ratio of parts A and B by weight. We poured it into the box we created and waited 24 hours for it to set.
Once set, we removed the mold from the 3D printed part and cardboard and one half of the mold was complete!
Gate 3
Now that we had one side of our mold, we needed to create the other side with the CNC cutter. We began by using SOLIDWORKS to design the positive piece, ensuring that the holes on the side were extruded/cut in the opposite direction as they were for the 3D-printed piece.
During the finishing cut, we ran into complications because the bit was too short, causing the CNC spindle to collide with our piece of wood when cutting near the top and bottom edges. To alleviate this issue, we attempted to use a dremel to round off the edges of our wood, which was moderately successful. However, we decided not to proceed with another finishing cut using a 1/16 inch ball nose like we had previously planned to, as the collisions from the first finishing cut had shifted our piece of wood slightly, and we did not want to run the risk of ruining our existing cut. Because we did not finish with a finer bit, we tried to add some of the missing detail (most notably the separation of the Smiski’s legs) manually using a dremel. This produced our positive CNC piece.
To create the silicone mold for this side, we repeated the procedure we used to create the first mold. We built a box of indeterminate size around the positive piece, using generous amounts of hot glue to make sure there would be no leakage. Then, we mixed a total of 210 mL of silicone (1:1 w/w A:B) and poured it into the box. After waiting for 24 hours, the second side of our mold was complete!
Final Casting Process
With both sides of our mold now in hand, we were ready to cast our Smiskis. In our first attempt, we pressed the two sides of our mold together and directly secured them with elastic bands.
We used the Smooth-Cast 305 (30 minute cure time), mixing a total of 60 mL (1:1 v/v A:B) and pouring it into the pour-hole of our mold.
After 30 minutes, we released the mold and found that the back of our Smiski’s head had been slightly deformed due to the uneven pressure produced by the elastics.
For future attempts, we decided to instead sandwich our mold between two pieces of wood and secure them altogether, as that would apply pressure more evenly and decrease the chances of mold deformation. We used the Smooth-Cast 300 (10 minute cure time), similarly mixing a total of 60 mL (1:1 v/v A:B). We added a bit of coloring to part A before mixing parts A and B together, and after pouring the mixture into the pour-hole of our mold and waiting for 10 minutes, we released the mold to unveil our structurally sound Smiski.
After repeating this process 3 more times, we had all four of our Smiskis, each in a different color using the following pigment.
We cleaned up all the supplies we used and proceeded to post-process them.
We first used the belt sander to quickly sand away the excess produced by the pour-hole, then manually sanded the sides of our Smiski until the separation between the sides was less noticeable.
The finishing touch was to fill in the eyes and mouth of our Smiski with black paint, and with that, we had our final products!
Overall, we’re both very satisfied with how our Smiskis turned out! Though the separation between the 3D-printed and CNC sides is still noticeable, the final casts were pretty symmetrical. However, as a result of us manually using a dremel to separate the legs on the CNC side, they definitely look rougher than the 3D-printed side. In the future, we would ideally choose a piece of wood that matches the dimensions of our mold exactly so we wouldn’t run into the issue of the CNC spindle colliding with the wood, which would then enable us to run a finer finish on the piece.
Cost Breakdown
Materials
PLA Filament – > $2.50
Silicone A -> $7.50
Silicone B -> $7.50
3 Blocks of Wood (dimensions) -> $10.00
Smooth-Cast 305 A – > $5.25
Smooth-Cast 305 B -> $5.25
Coloring -> $5.00
Cardboard -> $1.00
Hot Glue -> $15.00
Popsicle Sticks -> $3.00
Rubber Bands – >$0.50
Equipment – > Free with OEDK Access
Makerspace access -> Free with OEDK Access
Labor
15 hours for two people – > Minimum wage = $7.25
$7.25 * 15*2 = $217.50
Total Cost: $280
Clean Final Workspaces and Materials:
