There is a numberofpages on the Internet describing the process of
building a cyclonic separator. Some of them even provide some maths
and a quite detailed plan if you need a unit capable of taking you to
the Moon. If, however, you'd like a small unit that can help prevent
your home vacuum clenaer from clogging while you drill a hole to hang
a painting, you may feel a little deserted. I did too. I wanted to
know how much material I needed to build the thing and to check if a
slightly resized design still fits the sheet I had. Last but not
least, I wanted a nice flat template to cut out the inlet which, if
you think about it, is a strange shape. So I took my tools and started
1 The shape
First I created an OpenSCAD script to visualise a hollow cone.
The cone of cyclonic separator.
Looks nice but still does not help much in cutting. Let's iron it.
2 The template
With the above design exported as STL file we can start trying to
make it flat. STL is a very simple file format and luckily there is
a great script by nophead to parse it. Once parsed the shape needs
to be transformed so that the surface of the cone becomes flat. This
is what the conexform() function in the code below is for.
Remember to copy actual dimensions of the cone used in the scad file
or the transformation may yeild quite weird results.
When a "flat" stl file is ready. We need to import it to OpenSCAD
once again to convert it to DXF for further work. This is quite a simple task
The numeric arguments for rotation and translation above match the
values used to create the cone. If you change cones size you need to
adjust them. After pressing F6 in OpenSCAD we get a nice 2D shape
that can be exported as DXF.