GH_chapter_h08bt.txt
Chapter_8_Fabrication
142 Fabrication
Chapter_8_Fabrication
Today there is a vast growing interest on material practice and fabrication in combination with Computer Aided Manufacturing.
Due to the changes have happened in design processes,
it seems a crucial move and one of the ‘Musts’ in the field of design.
Any design decision in digital area,
should be tested in different scales to show the ability of fabrication and assembly.
Since it is obvious that the new design processes and algorithms do not fit into the traditional building processes,
designers now try to use the modern technologies in fabrication to match their design products.
From the moment that CNC machines started to serve the building industry up to now,
a great relation between digital design and physical fabrication have been made and many different technologies and machineries being invented or adjusted to do these types of tasks.
In order to design building elements and fabricate them,
we need to have a brief understanding of the fabrication processes for different types of materials and know how to prepare our design outputs for them.
This is the main purpose of the fabrication issues in our design process.
Based on the object we designed and material we used, assembly logic,
transportation, scale, etc.
we need to provide the suitable data from our design and get the desired output of that to feed machineries.
If traditional way in realization of a project made by Plans, Sections, Details, etc.
today, we need more details or data to transfer them to CNC machines,
to use them as source codes and datasheets for industries and so on.
The point here is that the designer should provide some of the required data,
because it is highly interconnected with design object.
Designer sometimes should use the feedback of the fabrication‐ data‐preparation for the design readjustment.
Sometimes the design object should be changed in order to fit the limitations of the machinery or assembly.
Up to this point we already know different potentials of the Grasshopper to alter the design,
and these design variations could be in the favour of fabrication as well as other criteria.
I just want to open the subject and touch some of the points related to the data‐preparation phase,
to have a look at different possibilities that we can extract data from design project in order to fabricate it or sometime readjust it to fit the fabrication limitations.
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8_1_Datasheets
In order to make objects, sometimes we simply need a series of measurements, angels, cordinatesand generally numerical data.
There are multiple components in Grasshopper to compute the measurements, distances, angels, etc.
the important point is the correct and precise selection of the objects that we need to address for any specific purpose.
We should be aware of any geometrical complexity that exits in the design and choose the desired points for measurement purposes.
The next point is to find the positions that give us the proper data for our fabrication purpose and avoid to generate lots of tables of numerical data which could be time consuming in big projects
but useless at the end. Finally we need to export the data from 3D software to the spreadsheets and datasheets for further use.
Paper_strip_project
The idea of using paper strips attracted me for some investigations,
although it had been tested before (like in Morpho‐Ecologies by Hensel and Menges, 2008).
To understand the simple assemblies
I started with very simple combinations for first level and I tried to add these simple combinations together as the second level of assembly.
It was interesting in the first tries but soon it became out of order and the result object was not what I assumed.
So I tried to be more precise to get the more delicate geometries at the end.
Fig.8.1. Paper strips, first try.
144 Fabrication
In the next step I tried to make a very simple set up and understand the geometrical logic and use itas the base for digital modelling.
I assumed that by jumping into digital modelling I would not be able to make physical model and I was sure that I need to test the early steps with paper.
My aim was to use three paper strips and connect them,
one in the middle and another two in two sides with longer length,
restricted at their ends to the middle strip.
This could be the basic module.
Fig.8.2. simple paper strip combination to understand the connections and move towards digital modelling.
Digital modelling
Here I wanted to model the paper strip digitally after my basic understanding of the physical one.
From the start point I need a very simple curve in the middle as the base of my design and I can divide it and by culling these division points (true, false) and moving (false ones) perpendicular to the middle curve and using all these points
(true ones and moved ones) as the vertices for two interpolated curves I can model this paper strips almost the same as what I described.
Fig.8.3.a/b.
First modelling method with interpolated curves as side strips.
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Fabrication
But it seemed so simple and straightforward. So I wanted to add a gradual size‐differentiation in connection points so it would result in a bit more complex geometry. Now let’s jump into Grasshopper and continue the discussion with modelling there.
I will try to describe the definition briefly and go to the data parts.
Fig.8.4.
The <curve> component is the middle strip which is a simple curve in Rhino.
I reparameterized it and I want to evaluate it in the decreasing intervals. I used a <range> component and I attached it to a <Graph Mapper> component (Params > Special > Graph Mapper). A <Graph mapper> remaps a set of numbers in many different ways and domains by choosing a particular graph type.
As you see, I evaluated the curve with this <Graph mapper> with parabola graph type and the resultant points on the curve are clear.
You can change the type of graph to change the mapping of numeric range (for further information go to the component help menu).
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Fabrication
Fig.8.5.
After remapping the numerical data I evaluated the middle curve with two different <evaluate> components.
First by simply attach it to the data from <graph mapper> as basic points.
Then I need to find the midpoints.
Here I find the parameters of the curve between each basic point and the next one.
I <shift>ed the data to find the next point and I used <dispatch > to exclude the last item of the list (exclude 1) otherwise I would have one extra point in relation to the <shift>ed points.
The <function> component simply find the parameter in between ( f(x)=(x+y)/2 ) and you see the resultant parameters being evaluated.
Fig.8.6.
Now I want to move the midpoints and make the other vertices of the side strips. Displacement of these points must be always perpendicular to the middle curve.
So in order to move the points I need vectors, perpendicular to the middle curve at each point.
I already have the Tangent vector at each point,
by <evaluate> component.
But I need the perpendicular vector.
We now that the Cross product of two vectors is always a vector perpendicular to both of them (Fig.8.7).
For example unit Z vector could be the cross product of the unit X and Y vectors.
Our middle curve is a planer curve so we now that the Z vector at each point of the curve would be always perpendicular to the curve plane.
So if I find the cross product of the Tangent of the vector and Z vector at each point,
the result is a vector perpendicular to the middle curve which is always lay down in the curve’s plane.
So I used Tangent of the point from <evaluate> Component and a <unit Z> vector to find the <XProd> of them which I know that is perpendicular to the curve always.
Another trick!
I used the numbers of the <Graph Mapper> as the power of these Z vectors to have the increasing factors for the movements of points,
in their displacements as well,
so the longer the distance between points,
the bigger their displacements.
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Fabrication
Fig.8.7.
Vector cross product.
Vector A and B are in base plane.
Vector C is the cross product of the A and B and it is perpendicular to the base plane so it is also perpendicular to both vectors A and B.
Fig.8.8.
Now I have both basic points and moved points.
I <merge>d them together and I sorted them based on their (Y) values to generate an <interpolate>d curve which is one of my side paper strip.
(If you manipulate your main curve extremely or rotate it,
you should sort your points by the proper factor).
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Fabrication
Fig.8.9.
Using a <Mirror Curve> component (XForm > Morph > Mirror Curve) I can mirror the <interpolate>d curve by middle <curve> so I have both side paper strips.
Fig.8.10.
Now if I connect middle curve and side curves to an <extrude> component I can see my first paper strip combination with decreasing spaces between connection points.
Fig.8.11.
I can simply start to manipulate the middle strip and see how Grasshopper updates the three paper strips which are connecting to each other in six points. |
