Assignment
This week assignment was design a mold and make something from a mold. It is a completely new thing for me and at first i don't know how to make it. Thanks to my instructor Anders i finally made my mold.
Design mold
I use rhino to design my mold. Design a mold is not easy, you need to calculate the size and metion the hole for pouring. Here is my design image. I design a little bowl that we can use in some chemical experiment.
And here is three view of my design.
Then you need to export as stl file. Go to fabmodules.org. Import the stl file. And change the x and y axis to set the image to the corner. You had to do this because the model that came out of Rhino was not using Z as up axis (Different softare different rules) therefore you had to rotate it in Fabmodules. Because you change the rotation in fab module that auto aligment did no longer match. Then export as rough mill mold. This took really long time..
Here is the progress of milling.
And here is my final mold!
Here is my design mold.
Mold in Rhino
Casting
We use oomoo as the material for the first mold(sorry i still don't know how to name it). Mix OOMOO type A and OOMOO type B in 1:1. Put them in a vacuuem bag and pull the air from the mold as follows.
Put blocks under the dome for better vacuum.
Waiting for 6 more hours and i get..
Then mix the "flour" and water in 10:1. Just a liitle water! Then pour into the first mold and push the two parts together.
Then wait for another couple of hours then open it. Ta da!
But i am too impatient. I open the mold too early that i broke some of my mold's part. But it looks like some thing from a mold!
Summary
Mold lesson for me is the most difficult class in which I need to learn a lot of knowledge, a lot of contact with no contact with common sense. When designing the model, not simply to design a model. Diagonal to consider when pores and merging models. This is very important. However, I have designed a circular symmetry of the mold, thus avoiding the problem of diagonal design.
Mixed plaster and water in the process, I also tried several times, but the effect of the resulting model is not very good. We consulted the professor, probably because the purchase of gypsum itself is not pure, mixed with a lot of impurities, leading to the final out of the model are very brittle.