20-2 Macro Pad

Industrial Design – Skill Exploration

Practicing Design Definition Skills while exploring into the Realm of PCB Design.

This personal project started with a curiosity during one of my internships, being exposed to the realm of enclosure design, working with and around Printed Circuit Boards, and re-legendable interfaces for the broadcast industry, I wondered how it could work for the regular desktop.

Project Timeline

October 2023 – November 2023

Design Processes

Secondary Research, PCB Design, Computer Aided Design, Prototyping, 3D Printing (FDM, SLS), Material Dyeing

Software

Altium Designer, Solidworks, Keyshot, QMK (Macro Pad Software)

Critical Project Drivers

To keep this project grounded within financial, skill, and manufacturing constraints, a set of design drivers was defined first.

Functionality

Controls for volume and miscellaneous actions such as scrolling or zooming
At least 20 Programmable key switches
Wired to the computer with detachable cabling
Screw points for stands or mounts
Custom Legend provisions
Backlighting for legend provisions

Components

Cherry MX Architecture Switches and Keycap Architecture
- Standardization with existing keyboard systems is important for cost, longevity and customizability of the resulting system.
Custom PCB Design

Overall Dimensions

No larger than 2 inches in height
As little depth as possible.
- As much as internal components allow
Width no longer than 12 inches
- the maximum footprint an Ender 3 FDM Printer can print diagonally with a 2 inch face height allows

20-2 Bill of Materials

PCB Design

Using Altium Designer, a schematic was drawn up, then converted into several traces. The final design was then sent to a supplier for fabrication.

Enclosure Design

The Rest of the enclosure was designed in Solidworks, while form was not the main goal for this project, a minimalist, unintrusive look was aimed for the enclosure design.

Keycap Design

Born out of a need to have a stylistic and aesthetically compatible keycap when COTS solutions were not fitting enough, a custom keycap design for this macro-pad was designed.

1. MX Switch

Commercial-Off-The Shelf Part
Prototype: Akko CS Crystal

2. Main Keycap Body

Intended Process: Injection Molding, ABS
Intended Finish: Translucent Black, SPI D1
Prototype: FDM Process, Clear PETG, Black Dye

3. Main Keycap Body

Intended Process: Injection Molding, PET
Intended Finish: Transparent Clear, SPI D3
Prototype: FDM Process, Clear PETG

Keycap Fabrication and Dyeing

Keycaps were printed in PETG with settings that make it as optically clear as possible.

While the eventual result is not as clear as desired, it yielded acceptable results.

Material dyeing with RIT Dye, Alcohol Markers and other mediums was also explored, eventually going with the first method that produced permanent and reliable result.

Enclosure Fabrication And Assembly

1. Baseplate and Mounting Hardware

M3 Screws
Feet: Commercial off the Shelf
PETG Baseplate

2. Electronic Components

Note: PCB Not Shown
MX Style Switches
Detent-less Rotary Encoders
PETG Switchplate

3. Main Body

SLS PA12

4. Knobs and Keycaps

Keycaps: PETG with Dye Process
Knobs: SLS PA12

Project Debrief

Developing a High-Fidelity Consumer Electronics Device Prototype

Learning About PCB Design

In doing this macro-pad project, i have learned a significant amount of information regarding the design of Printed Circuit Boards. While my knowledge is still elementary at best, i have learned to appreciate the intricacies involving its design which can range from routing to referencing device schematic data, as well as the importance of sourcing the right components for your board.

Delving into the SLS Process, Pushing FDM and Material Dying

This project enabled me to use the SLS Process for its main enclosure, where i was able to compare it to the more Common FDM Process, how its warping characteristic differs , what kind of fidelity can it achieve, and its surface finish.

In developing and fabricating the keycaps, where optical clarity was paramount, it made me push the limits of FDM, and the PETG material used, tinkering with settings to have the most optically clear-as possible keycap cover.

The Material dyeing aspect of the keycap design allowed me to delve into its benefits, what kinds of dyes work and how intense of a heat can these parts take before structurally deforming and obscuring its clarity.