0. Assignments for wk12

The assignments for wk12 were as below;

  1. Design a 3D mould, machine it, and cast parts from it.

1. Making the mold

This week, we learned how to make the mould and cast parts from it.


Since I loved the Japanese sweets, called 'Wagashi' in English, which means Japanese traditional sweets made of sugar and was famous for their beautiful design, I wanted to make its object this week.

I chose the shape of "Sakura", which is cherry blossoms in English as the assignments.

Japanese Sakura Sweets

Designing the Mold

First, I made the 3D design of Sakura sweets using Fusion 360 as below.

Sakura Sweets on Fusion 360

Since 3D milling function on ShopBot needed 'bed' of the object, I add the rectangle bed as below and finished to prepare 3D milling.

3D design with milling bed
Download the file

Machine set up of Shopbot

Below is the set up process of 3D cutting on Shopbot:

  1. Prepare the design files and move them to the laptop on Shoobot.
  2. Set the material on the smooth surface wood, fixing with enough number of volts and strong double-sided tape.
  3. Choose correct end-mill. If not, noisy sounds will be occurred by machine, you have to choose appropriate end-mill, cosidering the softness and thickness of the material.
  4. On Partsworks 3D, which is the supporting software to prepare the cutting blueprint, read the design file. During this process, you have to make and save two types of files: rough and finishing.
  5. Open Shopbot3, which is the software for controlling Shopbot, and read the saved file above. Before cutting, you have to set origin of x and y and z axis.
  6. After setting, you can start to cut. Duting cutting process, you have to pay attention to machine and check if the cutting procceed without problems.

Milling the Mold

Next, we learned 3D milling function of ShopBot, which was totally new for us. Local instructor, Michael, taught us how to prepare and set the 3D milling.

However, I made a mistake when I tried first by myself. I wrongly put the brick on the rough wood, so the material started to move when I started to mill as below.

Putting the material on rough surface wood

The error occurred as below, and the material was close to jump away. It was a bit dagerous...

Milling wrongly

Then I put the material correctly, which means on slippery surface wood, and paste the material on the wood with strong double sided tape as below.

Putting material on the support wood

Then, I was able to mill the brick rightly, and the output is the image as below. Though the shape was almost completed, the detailed part, for instance, the core of flower and borders of petals, were not milled correctly because the milling bit was bigger than the design.

3D milled brick

I used cutter to add the detailed design as below, though this was not 3D milling....

Adding the detailed parts

Finally, I made the mold to make the rubber mold like this.

Mold for rubber

2. Casting the object

Making the rubber mold

To make the final casting, we had to make the rubber mold from the mold which I made previously.

For making the rubber mold, we used;

  • Mold rubber: PMC-121/30 Wet
  • Mold rubber: PMC-121/30 Wet

    I mix the two type of liquid by the ratio 1:1 following the datasheet of the material; Datasheet of PMC-121_SERIES

    After finishing mixing the liquid, I pourred it to the mold which I made.

    Pouring the liquid to the mold

    Then, I had to wait over 17hours for the liquid becoming rubber. During this, we have to put them inside the chemical box, which can exhaust gas to outside since the liquid omit poisonous gas.

    Waiting to be harden inside the chemical box

    After waiting one day, I got the mold rubber which was beautiful and able to meet my expectations.

    Mold rubber of Sakura Design


    Since I made the mold rubber, finally I could make the casting. For casting resin, we used;

  • Casting resin: Smooth-Cast 300

  • Mold rubber enable us to make mass-production of the design which we would like to make. Though I do casting only one model this time, I wish to cast anotehr design a lot next time.

    Smooth-Cast 300

    What was different from when I made the rubber mold, this casting resing become solid very quickly, 15 minutes or so. Hoever, it was getting very hot during the process, so we have to treat the material correctly.

    Pourred resin in the mold rubber

    Though the datasheet of material told us that we had to wait only 20minutes or so, I left it as it was 1 hour just in case this time.

    Harden casting resin after 1 hour


    After the resing drying, I put it out from the mold rubber. The rubber was so soft that I was able to put it out without damaging the casting. Here is the image of the production of this week below.

    Rubber and casting

    'Sakura' by molding and casting

    Outline of this page

    1. Making the mold
    2. Casting the object

    Download output of Wk12

    Here are my output files for wk12:

    Lecture Material for Wk12

    Lecture Note


    Learning Support

    Videos of Wk12

    Here you can find this weeks's lectures on VIMEO:



    Checklist for Wk12

    • Design a 3D mould, machine it, and cast parts from it.
    Learning outcomes:
    • Design appropriate objects within the limitations of 3 axis machining
    • Demonstrate workflows used in mould design, construction and casting
    Have you:
    • Explained how you made your files for machining
    • Shown how you made your mould and cast the parts
    • Been surprised today
    • Described problems and how you fixed them
    • Included your design files and 'hero shot' photos of the mould and the final object