Overview:
This design focused on making an object that could be casted for each of my family members. The turtle with the “O” represented my favorite animal with my family name. Initially, the turtles were suppose to be able to stack on top of each other. However, complications within the process made this aspect unsuccessful. The overall project was fun.
There are 3 parts in completing the mold and cast. 1. Mill the positive 2. Cast the negative mold, 3. Cast the final positive mold.
Mold 1: 6″ x 3.5 ” x 1″ Wax block
Machine: Shopbot
Rough =10 min.
1/4″ ball nose
Spindle Speed= 9000
Stepover=15%
Pass Depth= .25
Flakes are a great sign of appropriate speed for milling wax. If too fast, the heat of the bit will melt it.
After a few rough cuts comes the finish cut.
Machine: Shopbot
Finish = 40 min.
1/32″ ball nose
Spindle Speed =9000
Stepover = 15%
Pass Depth= .125
Feed Rate =4
Plunge Rate= 4
The design on the shell didn’t come out correctly. It most likely was how I designed the depth of the letter. It also showed a bit of melting.
So I gave it a face lift. To fill the holes on the shell, I used hot glue. Now time to cast the mold!
Mold 1: Mold Star 15
Pot time -50min.
Cure Time- 4 hrs.
So many choices…
Mixing the solutions together was very simple. Its a 1:1 ration of each chemical substance.
After applying a release agent, hand soap, the Moldstar 15 was poured to the top. After waiting and waiting and decided to wait overnight, it was ready.
You can see the excess amount of pink hand soap used when peeled from the wax. The amount of soap caused a ton of tiny air bubbles in the mold.
The first mold also did not go into all of the crevasses. This will not be able hold the solution for the next step. Time to REMOLD!
The second attempt was again left overnight. Less amount of release agent was used and therefore little amount of air bubbles. SUCCESS!
Cast 1: Smooth-cast 300
Pot Time= 3min.
Cure Time = 10min.
The far right cast cured before the mold was full. By the 3rd attempt, the casted mold showed great progress but there were still problems with air bubbles. So I decided to experiment on a stiffer rubber.
Mold 2: PMC 121/30
Pot Time =30mins
Cure Time= overnight/16hrs.
The mold is beautiful.
This time, I clamped the mold together with rubber bands and plugged the original pour and ventilation hole with one of casted turtles.
The new pour hole will be located at the head of the turtle.
COMPLETE FABRICATION 