Design Goals
The primary goals are to create an enclosure that:
- Lets Arduino-based projects move from the workbench to the living room
- The design must be look like it belongs in a home
- Provides a platform for Internet of Things projects
- The design must be able to house an Arduino and WiFi shield (Net connectivity), along with human input (switches, capacitive touch, or optical proximity sensing) and output (indicator LEDs or haptic feedback) capability
- Can be fabricated with commonly available Maker tools
- Laser cutters and CNC routers
Design Principles
- Use natural or traditional materials (such as wood, stone, glass) wherever possible.
- These are the materials that typically make up our home environment.
- Use warm, natural colors
- This follows Alexander’s pattern A250
- Use dimensions based on a Fibonacci sequence beginning with 0.25 inches wherever possible on visible parts.
- The use of a Fibonacci sequence reflects the modular nature of the system.
- This establishes a preferred number for dimensions.
- This is aligned with Alexander’s A240 pattern and follows the Golden Ratio pattern.
- Use timeless design styling by blending ancient and modern design elements.
Early Sketches
The initial idea was to used stacked slabs to form an enclosure for an Arduino with one shield attached to it. Each slab is made from wood, giving a warm natural feel to the piece. Recessed LED lighting (within the gaps) can be used for an output interface for applications like a Pomodoro timer. Ideas for an input interface include: switches, optical proximity sensing, and capacitive touch sensing.
Dimensional Constraints
Connecting bolts (1/4-20 in various lengths), used in Ready-To-Assemble furniture, provide a nice looking visible fastener. The longest commonly available size is 70mm (-2.75″), which uses a matching cap nut. The hex heads on both the bolt and nut, along with the wide and flat head, give the appearance of a rugged, strong fastener. These bolts also make it easy to open up the enclosure when working on the internal electronics. Selecting this bolt to hold the stack of slabs together set the design height to 2.75″.
Another design constraint is to incorporate the Golden ratio into dimensions through the use of sizes related to each other by a Fibonacci sequence. Guided by Alexander’s half inch trim pattern and the Golden Ratio pattern, a base unit of 0.25″ was selected (1U), leading to preferred dimensions:
- 1U = 0.25″
- 2U = 0.50″
- 3U = 0.75″
- 5U = 1.25″
- 8U = 2.00″
- 13U = 3.25″
- 21U = 5.25″
- 34U = 8.50″
Notice that 3U + 8U = 2.75″. This suggests using 5U + 13U = 4.50″ as the width. Note that 4.50 / 2.75 approximates the Golden ratio. An interesting property of Fibonacci sequences is that a new sequence created by summing members creates a new sequence where the ratio of adjacent members also approximates the Golden ratio!
Since the slabs are square, this gives an overall size of 4.50″ x 4.50″ x 2.75″. Using the original sequence, notice that 1U, 2U, and 3U are common material thicknesses (a consequence of starting with 1U = 0.25″).
Preliminary Design
Given an 11U height constraint and slab thickness choices of 1U/ 2U/ 3U, a finite number of choices exist. Since enough room is required in the base to fit an Arduino and one shield, this requires at least 2 x 3U. This leaves 5U for the remaining pieces. A nice balance is 3U cap and 2U spacer. A quick test was done with some MDF blocks from the scrap bin (wrong widths), as seen in the picture. The configuration is reminiscent of buildings like Falling Water.
Here is a sketch with the correct dimensions. This was selected as the overall form for the enclosure.