Design Iteration Goals
The goals for this design iteration are:
- Create a photo-fabricated PCB for the shield based on Prototype V
- Lower the CNC milling time for the oak pieces
The same shield design that was CNC-routed in Prototype V was converted to Gerber files and sent to a PCB house:
The wood slab were modified to reduce milling time by simplifying the designs:
- The Cap slab was changed to have a shallower pocket to house the PCB. This also reduced the number of Lightguide slabs from four to two. The pocket width was increased from 3.5″ square to 4.0″ square to accommodate a larger lightguide.
- The Base slab was changed to a 2″ square inner opening and the rear opening for connectors was eliminated (the USB cable from the Spark Core will exit underneath the unit so the opening isn’t needed). These changes eliminated the need for two different base slabs.
In addition, a 45 degree bevel was routed (in a separate operation from the CNC milling) on the top edges of both the Cap and Base slabs. The bevel width was adjusted to 0.25″, keeping to preferred dimensions.
Here is a comparison with between Prototype V (left) and Prototype VI (right), both fabricated in red oak and finished with Tung oil:
The beveled edges improve the overall aesthetics of the design by softening the hard edges, making the top Cap more inviting to touch.
Here’s a close up (using the original Lightguide slabs):
Here is a bottom view with an un-assembled PCB (rubber feet have not been installed):
Components, including a socket for the Spark Core, were mounted. Here is the first board assembled:
The previous Prototype V code was used to test the board, which worked as assembled.
No videos were made.
- The simplified wood slab design (including beveled edges) is a good improvement
- The touch sensor still needed improvement
- Using the interupt on the Spark Core for touch sensing still had mixed results when connected to various power supplies