This week's summary
This week's exercise was to create a press fit construction
assembly using the Laser Cutter, with the added complexity of
creating an assembly that could be re-purposed to another
application.
My idea is to create a soccer ball using hexagons and pentagons.
The re-purpose assembly is a pot holder (trivet).
The Numbers
Hexagons = 20
Pentagons = 12
Connectors = 90 = ((20x6)+(12x5))/2
Connector Angle = 20 degrees (rough estimate based on 360 degrees
divided by 9 parts on any given diameter divided by 2 sides of
connector)
Cardboard thickness 0.170 inches (measured by Vernier)
Press Fit joint width 0.160 inches (selected by trial and
error)
The Process
The parts drawing was created in Inkscape. I have added a small
tutorial on
creating a press fit feature that may help.
For the connector joint, since we were using cardboard that
measured approximately 0.170 inches, the joint created for
interference fit measured 0.160, which appeared to work quite
well. A number of trial and error designs were done on the
connector piece. I realized after 1 or 2 iterations that an angled
connector would be required (I had incorrectly assumed that the
material would be pliable enough without an angled connector).
The SVG files are attached here (adjust for correct
quantities):
connector
svg
hexagons
svg
pentagons
svg
The Outcome
Inkscape worked very well after some initial frustration. The
process of running the actual job was relatively easy and quite
fascinating. The parts fit together very well and the final
outcome was good. The structure has a surprising amount of
strength and rigidity.
The re-purpose structure was basically half of the ball. This
required some half sized hexagon pieces to make the sides level.
Other Ideas and References
With more time I would have liked to consider a joint design
that would be flush with the outside of the ball. In addition, I
would have considered covering the cardboard with vinyl for
effect (black on pentagons, white on hexagons). Ideally this
would be done before laser cutting (stick vinyl to cardboard and
then laser cut shapes) but could also be done afterwards (cut
vinyl shapes on vinyl cutter).
During my project I was made aware by our tutor of a previous
project that constructed a geodesic dome inspired by
Buckminster Fuller. This takes the soccer ball principle one
level deeper where hexagons and pentagons are composed of
triangles. It's an impressive project.
Challenges
The assembly process was not trivial, particularly as the final
pieces were put into position. Inkscape took a lot of time so I
offer this tutorial
that may help.