Projections for CNC Production


#1

Is there an extension that “unfolds” a model into 2D? Think of a model of a basketball that is unfolded to be created on a CNC machine, or of the earth.


#2

there are extensions that unfold geometry, but creating a 3d ‘basketball’ suitable for cnc cutting in SU is a very advanced procedure in itself…
have a look at this link where a tennis-ball is being attempted by a number of people…
to then try and unfold, even the simplest of those, would require a lot of additional work…

SU may not be the best solution for sphere >> 2d conversion…


#3

If it’s a simple geometric shape like a sphere, you can create the 2D gores that are needed by using U-V PolyGen and the parametric equation form of the gore:

x = (D * Pi * v * cos(u)) / Segments
y = D * u / 2
z = 0

-Pi/2 <= u <= Pi/2
-0.5 <= v <= 0.5

where D is the diameter of the sphere and Segments is the number of gores to create.

For a basketball (9.55" in diameter) using 48 gores, this works out to:

x = (9.55 * Math::PI * v * Math.cos(u)) / 48.0
y = 9.55 * u / 2.0
z = 0

If you need a finer outline, increase the value of “U Steps” (you may need to increase the scale at some point if the resultant triangles become too small).

Model in SketchUp 8 format: gore.skp (75.3 KB)

You can download the plugin here: https://sites.google.com/site/spirixcode/code/uv_polygen.rb


#4

You might find some ideas in this thread:


#5

Lots of good info here that I need to process - thanks everyone! What I’m really trying to do is make a chair seat that involves a compound bend (front to back and side to side). I can use SU to make the bending form but then need to cut laminate pieces to stitch together. Since I’m unsure of the terminology, I got a few clues in the responses already (i.e. gores).