Hi All,
I am making a Geodesic Sphere and I am designing the connector plates.
The plates are simple hexagons and pentagons made of equilateral and isosceles triangles.
The 2D version is easy to draw but the 3d version is a bit harder.
The two critical measurements are the angle of the holes for the struts and the distance from
the centre. I have calculated these so now I have to draw it.
I have created a primitive shape of a triangular wedge with the required angles and holes of
the correct length. I have extruded various shapes I can use the SUBTRACT command on after
I have built the 3D shape. I have rotated the primitive to the correct angle. I have used an
ARRAYCLASSIC command to create the Hexagon as a polar array. So now I have a hexagonal
shape of 6 wedges at an angle with some parts I can subtract from the final shape.
The problem is that when I rotate the wedges along the outside edge of the hexagon, instead
of them fitting nicely together they split apart. I knew this would happen, what I don't know is
how to fill the gaps with solid material so that I can then UNION the wedges together, then
SUBTRACT the parts to make the holes.
The nearest I can see to do this is to use meshes somehow but I don't know much about them.
I cannot even work out how get the mesh menu on the top ribbon. I can bring up mesh commands
by typing them into command line but I don't know what they all are or do.
Ultimately what I need is the completed hexagon and pentagon shapes, with the correct distance
from centre and correct angle holes, in a single solid shape, that I can save as an .STL file to then
generate CNC code for fabrication.
For those who might have seen my posts before - yes this my homework for my Engineering Course.
The actual subject is "Manage Self in the Engineering Environment". So in case you are wondering
it is basically "if I was a real engineer and ran into this problem - what would I do?" The answer is
ASK SOMEONE! so here I am asking.
I have attached two files below. One is the 2D version of what I need and the other is where I am at
with this problem in 3D. The two critical values are the 24mm from the centre line to the end of the
15.88mm hole, and the 11.992 and 10.135 degree angles. The reason for this accuracy is that in theory,
the same connector plates could be used for a fabricated structure anywhere between 1m and 50m
in diameter - it is fully scaleable, the Strut sizes are an exact ratio of lengths to get the different sizes.
Also in case you are wondering, I have adjusted the precision of some numbers because they are not
critical, so when something says 5mm it may actually be 5.075 because it doesn't matter.
Thanks in advance for your help all.
Cheers
Andrew
Solved! Go to Solution.
Solved by dbroad. Go to Solution.
Study the attached to see if it a result you want.
XLINE added the blue lines for guidelines as to where the solid is. Snapped to points and used M2P to locate xlines centered in gaps.
Top and bottom closed 3dpolylines and lofted
Subtracted the center post.
You can subtract a solid for the other hole and array the result, union for one solid if that is what is needed.
It looks like you are a student, so I will limit my answer to items that won't do the work for you.
Hi All,
It was a bit of a Saga, but after a software upgrade to AutoCAD Mechanical 2022, I started from
scratch and completely re-drew both components. Even that was a problem as I then had to
export them to 3D printable (.stl files) and CNC readable (.stp files). For those interested, the final
products are below.
Thanks again Community for your help.
Drewpan
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