Plastic is Forever

Creating Tomu's Injection-Molded Case

Sean Cross - https://xobs.io/ - @xobs

[Image of Tomu]

[Image of Tomu Case]

Outline

  1. Manufacturing the Case
  2. Designing the Case
  3. Understanding Plastics

About Me

  1. Novena
  2. Tomu
  3. Fomu

Manufacturing is Fun!

Factory Tour!

Front Door

Bags of Plastic Pellets

Inside the Bags

Into the Machine

Pulling a Shot

Factory Mold Bases

Tomu on its Mold

Both Mold Halves

Bottom Half

Ejectors

Cases on Runners

Factory Edits

Tool Model

Designing the Case

3D Printing

Almost (but not quite) entirely unline injection molding

  • STL vs STEP
  • Overhangs
  • Support structures
  • Flow rate/lines
  • Time taken
  • Family molds

Hardware

Software: FreeCAD

FreeCAD Example

FreeCAD can create STEP files

FreeCAD can read KiCad files

KiCad PCB inside FreeCAD

1) Open the PCB

First, open the PCB in FreeCAD

1) Open the PCB

Click 'Create Sketch'

2) Create a sketch

Creating constraints on the first sketch

2) Create a sketch

Creating constraints on the first sketch

2) Create a sketch

Creating constraints on the first sketch

2) Create a sketch

Creating constraints on the first sketch

2) Create a sketch

Sketch done, starting pad

3) Pad the sketch

Done with the pad

3) Pad the sketch

Done with the pad

3) Pad the sketch

Pad at an angle

4) Repeat as necessary

Create sketch for pocket

4) Repeat as necessary

Complete sketch for pocket

4) Repeat as necessary

Create a pocket

4) Repeat as necessary

Create a pocket

4) Repeat as necessary

Create a pocket

4) Repeat as necessary

Pocket with no PCB

4) Repeat as necessary

Click on face for sketch

4) Repeat as necessary

Pocket with no PCB

4) Repeat as necessary

Pocket with no PCB

4) Repeat as necessary

Pocket with no PCB

4) Repeat as necessary

Pocket with no PCB

4) Repeat as necessary

Pocket with no PCB

4) Repeat as necessary

Pocket with no PCB

4) Repeat as necessary

Pocket with no PCB

4) Repeat as necessary

Pocket with no PCB

4) Repeat as necessary

Pocket with no PCB

4) Repeat as necessary

Creating a pad for the alignment bump

4) Repeat as necessary

Creating the sketch for the guiding slots

4) Repeat as necessary

Finished case without PCB

4) Repeat as necessary

Finished case with PCB

5) Check with reference parts

Test with models

Here's what we sent to the factory

STEP model we sent to factory

And here's what they sent back

Real World Fun

And the problems you'll face

Clothes peg

Aircon Remote (Front)

Front of the aircon remote

Aircon Remote (Back)

Back of the aircon remote

Aircon Remote (Front Cover)

Cover from aircon remote front

Wine bottle opener

Kinder joy

iPhone 3G

Conclusion