|I figured that installing vert2.pl is inconvenient for
most people, so I created a wrapper around it so it
could be run as a web page. You'll find the nose
To use the calculator you create two data files on your
computer. Then you browse for them on the nose calculator
page, select what you want to generate (e.g. an image,
labels, etc.) and then click "Do It Now".
To create these data files you'd need to design a
tensegrity structure. Read about that on the
Building a Model page.
Once you've uploaded a pair of files the nose calculator
will remember them for you for up to a day, as long as you
don't leave the page or upload new file, whichever comes first.
When generating images, be sure to hold down the shift
key and click reload in the window displaying the image
if you have already generated an image once. This ensures
that you see the latest version of the image, and not the
one cached in your browser.
If you want to keep an image, put your cursor over it and
choose "Save Image As..." from the menu that appears when
you hold your left (or only) mouse button down.
The nose calculator is based on the premis that you are
building a symmetrical structure out of struts which are
connected together at verticies whose coordinates you have
reflected in your vertex data file. It assumes that the
struts will need some extra length so that a hole can be
drilled in its end where the vertex actually goes.
For more information on how struts can be cut and made into
a structure, see The Home Dome -- lots of pictures of the
whole process from measuring struts through final
The measurements of X, Y and Z for each vertex are points.
The nose calculator assumes that the struts will be joined
together by drilling a hole near each end of each strut,
and connecting struts through those holes using carriage
bolts. So, the nose calculator needs to know how much
length needs to be added to each strut so the hole is
far enough from the end of the strut that there is sufficient
mechanical strength. That is, if you drilled too close to
the end, the carriage bolt might tear through the end
of the strut during one of those 70 MPH dust storms that
have been known to hit the playa.
So, the nose calculator allows you to specify the length
of material to be added to each strut and this is called
the "end bonus". An end bonus of 2" means that you are
planning to drill the connecting holes centered 1" from
the each end of the strut.
The Margin for Error value allows you to input a reasonable
margin for error in measurements you'll be making when
you cut. This is useful because would you want to not use
the remaining portion of a strut simply because it was\
0.0001 too short? No, you'd look at it and say, "What luck!
It's already the right length!". If you think the closest
you'll be measuring is 1/16" then enter the decimal
equivalent of that.
The kerf width measurement accounts for the thickness of
the blade or abrasive cutting wheel you are using to cut
the conduit. If you are using a pipe cutter (the kind they
often use on plumbing pipe and even copper tubing) then
you may find that you have a kerf of 0 -- that is, no material
is lost when a cut is made. But any kind of sawing action
will remove material equivalent to the thickness of the
blade. The nose calculator accounts for this because when
you add up all the kerfs, it can be quite significant in
any given length of conduit. This is especially true
because the nose calculator endeavors to place struts
in a given conduit to minimize waste. Sometimes the waste
in a given length of conduit is less than the sum of the
kerfs. Without taking them into account there wouldn't
be enough conduit left for the last strut in that case.
The fact that the nose calculator assumes your structure
is symmetrical means that you only have to measure and enter
data for roughly half of your verticies. This saves a lot
of work, and also allows the nose calculator to render
half of the image when that makes sense (such as for a
side view). Some of the struts will be on the line of
symmetry, so the struts data file lets you identify these
by noting that only 1 of them is required. The nose
calculator treats these slightly differently than those
that are mirrored left and right.
At this point there is no way to create a non-symmetrical
structure using the nose calculator, but at some point
in the future I might adapt it to do so.
The nose calculator also lets you specify a list of
struts whose coordinates you want to see. This is useful
to learn the size or position of various parts of your
structure. For example, the Desert Nose has a deck inside.
When I ask for the coordinates of one of the struts in the
deck I can read the height of the deck as the Z coordinate
of the strut I chose.
The nose calculator examines your vertex data to produce
dimensions (Length, Width, Height), based on the maximum
values for the Y, X and Z dimensions respectively. That's
right: Length is determined by Y, Width is determined by X,
and height is determiend by Z. This is because when I
taped my Desert Nose model onto 10 squares/inch graph paper
to measure its verticies, the X axis was in front of the
nostrils and spanned left and right. The Y axis when
down the centerline of the nose, from between the nostriles
back to the furthest portion of the nose bridge. The Z
axis was up out of the graph paper (normal to the sheet).
That is, the Z axis was its "height".
I measured my vertexes by creating a tiny plumb bob. I
You can make one by taking a needle and threading some
thread through its end. Then taking a lead fishing weight
about the size of a BB and clamping it on 3/4 of the way
away from where you fastened the thread. When you hold
the thread the needle should point straight down.
I'd hang the thread over the vertex and use my finger to
dampen the swinging. When it was still I'd make a dot on
the graph paper right under the point of the needle.
This would give me the X and Y coordinates. For the z
Coordinate I'd use a metal ruler I had which had its
measuring region begin right at its edge. Another
technique I'd use was to take two drafting triangles and
use one as a base and one as a sliding measure. Then I'd
make a small pencil mark on the base triangle when the
sliding measure lined up with the position of the vertex.
Then I'd measure the height as the distance from the
edge of the base triangle and the mark I'd made.
Once you make your measurements and create your data files,
you can generate some images to look for errors in your
data. I found several errors in my data including:
- Incorrect coordinate values (transposed X and Y)
- Two struts had the same number
- There was a missing strut
It would have essentially been impossible to spot these
errors without the nose calculator. I created many
views of one slice or another from different perspectives
to be able to spot what was wrong.