In our final project, Alexis and I decided to make an owl(https://www.thingiverse.com/thing:709768), so that it is neither too simple nor too complex but still meaningful. Below is the owl we chose to make. We decided to split the owl into its front and back. We 3D-printed the front part and CNCed the back, since the front is too complex for the CNC to cut.
Here is the split model we are going to make.
The front part of OWL, which will be a 3d printed part of the mold due to more complex geometries and overhangs.
Back part of OWL, which will be CNC’ed due to mostly similar geometries and very minor overhangs. The 3D printed part went well.
We used the Bamboo software in the OEDK to print it. However, we met a lot of problems when we were trying to machine it via the CNN machine. We create the tool path by using the VCarve software. The height of our project is over 4 inches, so we can only use Shapeoko. We planned to use ⅛ bit for rough cut and ⅛ ball nose for smoothing. However, the ball note bit is hovering above the owl throughout the whole cut, and we can not change it.
Therefore, we decided to sand and smooth the project after we cast the project by ourselves. (CNN part picture)After the two positive parts are ready, we are ready to make the mold box by pouring silicon.(pics for the silicon mold boxes)The two halves didn’t match since we accidentally reflected the STL in the STL file. So we cut the wrong positive parts and added wood pieces to the negative parts of the back of the owl silicon mold box. (Picture of the new mold box of the back of the owl)We are ready to cast the final pieces now. The volume of our project is 160cm^2, so we poured 80 cm^2 of part A and part B resin into the mold box after we mixed it. Here is the picture of the resin waiting to cure. We make a red owl by adding red pigment to it.
After we cast all the owls, we sand the back of the owl and other rough parts to make them smooth as post-processing. Here are the final owls we have!
Cups – $4.48
Silicone – $75/quart kit200 gram Part A + 200 g part B per mold * 2 = 400 gram per part. = ~$37.5 By our weight amount
Smooth-cast urethane – $25.70 for trial unit (1.9lbs)
Smooth-cast urethane – $24.88*2
Red Pigment – $33.03/9 = $3.67
Popsicle stick to mix – $4.99
Black+Decker – $40.42
Bambu carbon – $999.99
White PLA – $19.99
Shapeoko Pro XXL – $2800
Labor costs – ~15/hr * 12hr/person * 2 people = $360
Total: $4346.5
