Week 10

Group Assignmet page

design a 3D mold around the stock and tooling that you'll be using,
machine it, and use it to cast parts

This week, I proceeded with the molding and casting process to make the locker handle.
Before proceeding with the full course, I practiced making small things with Instructor Yongwoo and Classmate Seunghwan.

The material used is a mold star 30, which is the master of the endmill 6t fan.

The ratio of base to hardener in mold star 30 is 1: 1, pot life is 45 minutes and cure time is 6 hours.

The mold star 30 had a long pot life and used a deformer for about 5 minutes.

Done!

After the exercise, I decided to make a locker handle, and the materials I used was machineable wax and chemical wood.

Tool path

First, I decided to mold the machineable wax by cutting it with cnc.
The advantage of machinable wax is that it can be recycled when it is melted by collecting the scraped materials,
but unfortunately it has been mixed with other materials and we could not recycle large quantities.

Then I used urethane to make the master, I used task 13.
TThe ratio of base to hardener in Task 13 is 1.2:1, pot life is 3 minutes and cure time is 20 minutes, so I had to go as fast as possible and I could not use the deformer.

Because the size of the handle could not afford the mechanical wax, the walls were temporarily set up with waste wood.

I took care of the master carefully, but I was very confident that I had to work on it.
I think that the master has come out very well when I pulled out the air bubble by hand.

I then cut the chemical wood to make the other side and used the same task 13 to make the master.

Oops, I was overflowing in a hurry..

I peed it off after drying it...

It failed.

Twice! (WTF?)

I expected it to come out like the first one..

So, task 13 was extruded and made using a mold star 20T.

The ratio of base to hardener in mold star 20T is 1: 1, pot life is 6 minutes and cure time is 30 minutes.

I thought twice when I failed, that the combination of chemical wood and urethane is not very good.
In my opinion, chemical wood is not as smooth as machinable wax,
it has to be hard on both material properties,
and because of the lack of easy angle, it has to fail for these reasons.

Anyway, I finished the master production.

I did not want to experience like urethane, so this time I asked the instructor for advice.
What I wanted was a solid enough to serve as a handle, but the instructor recommended it for plaster.
There are two types of gypsum here: one is a basic gypsum, the other is a high-strength gypsum,
but I wanted a solid one, so I proceeded with high strength gypsum.

Reinforced plaster L type

In the case of this gypsum, the ratio of gypsum to water is 100: 35,
respectively, and acrylic paints were added to match the color of the wood.

To make sure, we made a small rectangular parallelepiped to carry out a simple strength test.

I tried to knock it on the ground and try to knock it, but it was harder than I thought and I decided to make a handle.
And, according to the advice of the instructor, I used UMR, a mold release agent that does not spray a release agent on the master.

It is a finished piece that was taken out immediately after casting.
When tightened with a clapper, the silicone became bulging, and the shape was slightly shifted even though it was tightened only to not leak.
Still, there was no problem to use it, so we proceeded to post-processing.

After the sanding, I coated the surface of matt lacquer and it looks like a very good product.