W6: Milling Simulation

This week, we started learning a bit about subtractive fabrication and toolpath generation with this modality. I would say that understanding additive methods was more intuitive for me. CNC simulations require lots of machine-specific input (like the tools).

To simulate the milling path, I picked a box to house 1 Intel Realsense depth camera and 1 Raspberry Pi. The box dimensions are 13.7 x 10 x 3.5 cm for the main body and 13.7 x 10 x 0.75 cm for the lid. I also 3d-printed the box using Ender 3. Since the main body is deep, I couldn't find a way to simulate any no-collision paths. That's why I only simulated the lid of the box.

Fusion 360

I found a Thermal Load simulation under the Simulation tab. Usage was intuitive: I closed the box with the lid and clicked on auto contacts. Fusion 360 was smart enough to understand these two parts were touching and adjusted the setup accordingly. Then I specified a thermal load that may simulate the working condition of the box. The result came in less than 2 minutes, and its as shown above.

I specified a stock material for the lid of size 14.7 x 11 x 8 cm with an offset from the bottom of 1 mm. I don't think this is a standard stock size but since I will only simulate this object on Fusion 360, I wasn't concerned with it just yet. I set up the coordinate system to correspond to the upper left corner, Z pointing up.

Then I created a Face milling with #171 - Ø1.9675"R0.015" face (2" Face Mill). This operation removed extra material on the surface of my object. Then I used 2D Adaptive Clearing to remove material inside the lid edges with the same tool. I had to turn on the Multiple-Depths option to prevent tool collision. And I used the same settings to remove extra material outside the lid edges. I wasn't too concerned about slightly rounded edges of my case because they are not obstructing any functional parts.

I duplicated Setup1 to use the same stock material. Then I changed the stock origin to the far-left of the other side of my part.

I started with a Face operation with #171 - Ø1.9675"R0.015" face (2" Face Mill) again. 2D Adaptive Clearing with #164 - Ø1" flat (1" EM Short) helped me to remove the outer contour of the lid. I had to give a bottom offset of 2 mm operations like this that pierce through the material block. I cleared the big opening with the same tool, and then used #114 - Ø1/4" flat (1/4" EM Short) to remove concentric fan openings (the gap is smaller than #171).