🧪 Week 13: Molding and Casting

👯‍♂️ Teaming Up for Fun and Efficiency

This week, my good friends Sohan, Devanshi, and I decided to join forces — to save time, efficiently use material, and most importantly, have fun!

📏 Measuring the Wax Block

First and foremost, I took measurements of the wax block we were going to use for making the mold. Then, we figured out the dimensions in which we could design our first-ever mold.

💡 Choosing What to Model

We pondered a lot of options for creating our 3D model — from ancient Indian weapons to low-poly animals. Finally, staying true to our Product Design specialisation, we locked in on creating tools.

🔨 Designing My Tool — The Hammer

I took up the hammer.

Then I opened up Fusion 360 to model my tool. First, I made a rectangle based on the dimension limits and began modeling. A few sketches, multiple extrudes, and countless offset planes later... my hammer was ready!

🧩 Combining the Models

Next, I imported the models my friends had made to combine and make a single .stl file for the mold.

To import someone else's model in Fusion 360: - You need their .f3d file saved locally on your system.
- Click on Insert > New Component, and then rotate/place it wherever you want.

After combining all our models and making walls for each, we exported the mold as an .stl file.

🖥️ Setting Up for Milling

We revisited an old friend from Electronics Production Week — the Rolland SRM-20.

We used the V-Panel software to set the origin of all three axes, and then we dove into a new software — SRP Player.

alt text Importing our model in SRP player Specifying the type of cutting process Creating a toolpath Specifying material Choosing the milling process Aligning top Preview of the path Drill bit specifications Creating a toolpath Drill bit selection menu alt text Toolpath preview Starting to cut Setting origin point Milling finished

⏳ The milling file took 5 hours to roughen and finish.

Milling process

alt text Ball-end bit Attaching the wax block Setting-up the machine Origin set Milling process Milling result

😅 A Realisation and a Pivot

Halfway through the milling cycle, we realised that I had created a mold that was not radially symmetric. That meant I wouldn't be able to make a 2-part mold out of it.

Our spirits took a hit. 🥲

Hours of aimless web surfing later, an idea sprang up — What if we made spintops?

Radially symmetric? ✅
Fun? Absolutely! 🎉

🌀 Making the Spin Tops

I promptly made a new model in Fusion, imported all models into one file, created a new mold, and exported it as an .stl.

Set it up again in SRP Player, and began another 9-hour milling cycle.

I also extruded the base slightly and 3D printed the same file. We now had two mother molds.

This time, I followed the advice to use holes for alignment while casting — added 5 mm holes on both sides and 3D printed pegs of the same size. Adding a pouring hole Adding alignment pegs Final mold

🛠️ A Makeshift Solution

One of our mold walls had been milled away from the wax due to a slightly offset origin. We made a makeshift container using some acrylic lying around. Online tool for making a quick box

⚙️ Unexpected Machine Stop

Our machine stopped midway because the collet of the motor touched the material. We had to: - Reset the Z-axis
- Run the entire cycle again

Because of that: - 2 out of 3 tops weren't finished properly
- The 3rd top, which hadn’t even been roughened yet, came out very smooth 🧵

alt text Mold Result

🧫 Silicone Mixing Time

Now came the interesting part — enter silicone mixing! 🧪

Our mentor instructed us on the mixing ratio:
1 part hardener : 10 parts silicone.

We used:
- 🧤 Gloves
- 🥽 Safety glasses
- 🧴 Clean mixing containers
- ⚖️ A weighing scale

We mixed the silicone, carefully folding to avoid air bubbles, and poured it into our molds.

alt text Following safety guidelines Weighing the silicon Weighing the hardener Pouring Folding with caution Pouring into our molds Tapping to get the bubbles out

🖨️ The 3D Printed Mold

The 3D printed mold turned out really smooth too.
Yes, we could see the layer lines, but nothing that a little sanding can’t fix! alt text 3D printed mold result