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week9

*assignment

--group assignment:

review the safety data sheets for each of your molding and casting materials,
then make and compare test casts with each of them

--individual assignment:

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

1.Learning how to mold and cast.

First, I started to learn from tutorial
I could understand how it works.
So I could just start to design my mold.

2.Designing my mold.

I wanted to put korean traditional detailed design.
So I chose Dancheong(third image is the explanation for Dancheong)
So I searched images(first image) and picked up those two images(second image) for my mold.

soap

I tried to design in Fusion360.
I made the design for my Dancheong pattern soap.
And I thought it was gonna be perfect.
But problem happened.

combine

For milling, I need only 1 body and get stl file from it.
So I tried to combine. But it didn't work.

extrude

I found why it happened.
Because I made line and extruded it to seperate parts.(because of appearance.)
So I can't combine whole body and line extruded bodies.

extrude

Still I needed line to make sure things seperate.
So I tried to extrude with very small difference.(0.01~0.02)
And then I got just one body and stl file from it.

3.Milling my mold.

I put my stl file on Fabmodule to mill it.
And first 'show mesh'.

Why 'show mesh'?

Because 'show mesh' shows 'how it would be milled'.

heightmap1

The next step was 'heightmap'.

Why 'heightmap'

'Heightmap' is different from 'showmesh'.
On showmesh, we can't see with angle.
But on heightmap, we can see with angle.
So that's why we should put 270 not 90~.

It's really important espically for me.
Because I made line to seperate parts.
So I should see how it worked clearly.
Low dpi(left image) made not clear one.
On the other hand, High dpi(right image) made clearly.

/setting1

The setting for milling is here.
I think changing 'Units/in' is really important.
Usually we get used to mm,cm but fabmodule default is inch.
So before milling, you should change this!! (if you need!)

setting finish

Finish setting is almost same except tool diameter(I used 1mm end-mill) and end mill type(I used ball end mill)
Before doing this week assignment, I refered to last year students page.
All they told about this.
So you also should make sure it!!

molding mistake

At the first time I tried rough cut, it didn't move as what I had thought.
From my intention(or design), End-mill was supposed to make just square hole.
But it didn't.
Jinhyuck told me it's because my design size is the same as wax size.
And when I calcultated, actually wax size is smaller than 150,40,90(width,depth,lenth).
So I dragged my end-mill outside of wax and set 0.0(x,y).

molding final

But it also didn't make square hole though my trial.
It was really close....

complement

So as to make up hole, I put acrylic board to my wax.
Above bond is what I used for.
I was just given by this from fablab Seoul manager.
I didn't know how difficult to put something to wax.
But Rodrigo told me it is really difficult, So explain how you could do it.
And Now I'm ready to start molding.

4.Molding and Casting

Molding

Material:Mold star 16

Datasheet
Pot Life: 6min (about 3min for mixing + abut 3min for pouring)
Mix ratio: 1:1 by weight
Cure time: 30min
Shelf time:limited and should be used as soon as possible.

Instructions

-keep the trash bin close.
-Wear safety glasses, long sleeves and rubber gloves(Only vinyl, not Latex)
-be careful for the alchohole tissue.

I wanna make sure one thing.
At the first time we tried molding and casting, we all failed because of the shelf time.
Seeing the instructions for materials, shelf time is limited and materials should be used as soon as possible.
Our old one made us fail.
So we ordered and waited for getting new one.
And then we could start again.
Make sure to keep your materials, following the datasheet.

Before molding physically, we used releasing agent for better result.
Releasing agent is not necessary.
But it can help demolding easier when casting into most surfaces.
So we used soybean oil.

stir

Stiring well before mixing and pouring.

molding

Mixing two materials, calculating the ratio.

molding

And then pouring.
At this point, we should follow advice on datasheet.
'For best results, pour your mixture in a single spot at the lowest point of the containment field. Let the rubber seek its own level.'
Here 'best results' means less air bubbles.

molding

After 30 minutes, I could get my mold.

Material:Urethan task resin

Datasheet
Pot life: 7min
Mix ratio: A:B = 115:100 by weight
Cure time: 60min
Shelf time:limited and should be used as soon as possible.
molding

With almost the same process as molding, I could get my cast.
The differences are the ratio(115:100) and cure time(60 minutes).

Downloads

my design stl file