week 12
Moulding & Casting.
Assignment:
Design a 3D mold, machine it, and cast parts from it.
Design a 3D mold, machine it, and cast parts from it.
Guillermo Jaramillo :: Fab Academy 2017
Fab Academy 2017
I use autodesk inventor to design a circular medal with a repetitive pattern design.
First I tried with a lanceolate sheet design and a subtractive rib in the middle, for which use tapper extrusions, but in the end result the probability that the mold is very difficult to manufacture by the subtractive process is high.
Also at the time of casting the depth of the ribs could cause the final result to fail by fracture in the mold.
First I tried with a lanceolate sheet design and a subtractive rib in the middle, for which use tapper extrusions, but in the end result the probability that the mold is very difficult to manufacture by the subtractive process is high.
Also at the time of casting the depth of the ribs could cause the final result to fail by fracture in the mold.
To remedy these drawbacks, I designed a second solid of a circular medal, without ribs, with only a pattern of twelve occurrences of a single tree leaf.
Here is the detail of the pattern with the ribs.
So, the next step is save the model in STL format and open it in the software called SRP Player to start the task of cutting in the wax mold. First to configure the size of the wax block.
Once this is done, proceed to fix the depth of draft and the type of cut on the mold. The software calculates the time of the job too.
The next step is to choose the drill bits to start the draft, in this case the 1/8 "square and round tips have been chosen. It is also defined how many times the cuts and polishing passes will be made. In this case, two cutting passes and two polishing passes have been defined.
After this, the wax mold is fixed in the sacrificial bed. Once this is done, the cutting job is started as shown in the images.
In order to prepare the negative mold, I chose to use liquid rubber, of the Smooth On brand in the model oomoo 25. Which is mixed in equal parts and applied on the newly finished mold.
While the liquid rubber hardens, it is necessary to make a box of MDF to be able to then empty the mold with some type of resin or plastic or cement.
To cast the mold, choose smooth-liquid liquid plastics in the smooth white 305 model, which is mixed in equal parts and drained in the liquid rubber mold using the MDF box.
Once the plastic set, I began to unmold it by opening the box by the sides.
Finally in these photos you can see the finished final mold, next to the positive in wax and the negative in liquid rubber.
I also chose to make another mold using Hydro stone cement and Dry Stone, from which I chose Dry stone to re-cast the project and the results were very good as you can see in the photos. The ratio of mixing is about 20% percent of water of total weight.
Finally here I show the results in liquid plastic and dry stone.