| Ligno3D Designer is not just about
concocting fancy objects on the screen. The ultimate aim is to
help you build such objects in the flesh. You might think a
geodesic dome, for example, is just about impossible for a home
craftsperson to build in the back yard. In fact, it
turns out to be relatively easy. Ligno3D Designer gives you the
exact dimensions and angles needed to build such objects. It
then becomes an exercise in how well you can translate the plans into the
parts to be assembled. Comprehensive notes on actually building
objects are included in L3DD's help system, which is also the user manual.
____________________________
The fist object I
tried was a small geodesic dome (CubbyHouse) built with particleboard and biscuit joints. Prior to
this I feared that small errors might accumulate and make assembly a
nightmare. In fact it turned out to be quite easy — despite some
faces not being cut with perfect accuracy. The inherently strong
triangle-based structure ensures that minor inaccuracies translate into
small gaps that don't
matter. Similarly, the fully-enclosed SoccerHead
object, built out of MDF, went together amazingly well — just a few
edges needing minor shaving with a hand plane. Both structures
are as solid as rocks.
L3DD V3.50 can now do dovetailed faces, as well.
____________________________
To transfer faces from Ligno3D's plans to the panel material you need a 4H
pencil, a good steel straight-edge and a beam compass (also called a 'trammel'). Use
the compass and triangulation to draw the faces from the edge lengths and diagonals
shown on the plan. Using a protractor is not
as accurate. The faces are 'rough cut' before accurate trimming.
Your average handyman power saw is not
accurate enough to trim the faces. You can buy a suitable 'panel
saw' at some cost. I made a traveling-table saw
('Ryburn's
Folly') using a Triton® precision saw mounted under a hinged flap.
The angle of the flap is controlled by a clamped telescoping strut with
a
fine screw adjustment. On the opposite side I used two Quad Ball® sliding
door tracks to guide the table along a perfectly straight line.
A trial cut serves to align an adjustable straight-edge. The work
is then moved so that the pencil line lies exactly under the straightedge, which is
then hinged out of the way for the final cut. A thin 4H pencil
line is split down the middle. Private individuals are free to
copy this saw for their own use, but commercial manufacture is subject
to Ligno System's intellectual ownership.
____________________________
To assemble the faces I used PVA glue
and biscuit joints. 50mm x 2mm nails into pre-drilled holes hold
the edges together while the glue sets. Size 20 biscuits are used,
normally two per edge. When gluing, several faces should be joined
at one time so that the correct interfacial angles are achieved by
triangulation, rather than relying on the solid angles cut into the
edges. Half-interfacial angles were used for edge cuts, but these
sometimes require minor chamfering at the vertices. L3DD has an
'origin-centric option' that produces a perfect fit where three or more
faces come together, but this often requires edge-cuts of
less than 45º.
Although these techniques are not
appropriate to large geodesic domes, Ligno3D Designer still gives you the dimensions
required to build the necessary framework
structures. The framework is then
covered with suitable panel material.
See also Designing Geodesic Domes and
Frameworks. |
'Ryburn's Folly', a traveling-table power saw
Biscuit joints are 'forgiving'
Biscuit jointer in action
Rope trick, used to achieve 'closure' |
