Hello folks,
is it feasible with any version of Rhino3D, to create a progressive SPIRAL ?
THx & kind rgds,
franz
Hi Franz- the Pipe command will allow variable radii, I am not sure from your image where the spiral comes into it.
-Pascal
from the image, it looks like the pipe diameter stays the same and it’s the spiral’s diameter that’s changing?
if so, try drawing the centerline curve of that thing then use _Spiral -> Around Curve.
set the first point and radius… then the second point and radius can be larger/smaller than the first.
EDIT-
as in, i’m reading the picture as a variable spiral around a curve… which is then pipe_d
?
Hi Pascal… that was damn speedy … :-))
Well.
What You see there, is a “Manmade Tornado”- chimney, in a tropical lagoon.
According to my Patent
DE102013007836B3_1(1).pdf - directupload.net
Anyway. The updraft of that “Tornado-Spiral” depens on th volume of the Torus’ it’s formed of.
In oder to withstands crosswinds at higher altitudes, a greater updraft is deireable there… hope I somehow could bring this across.
kind rgds,
franz
Oops… THAT IS IT !
But that’s no big deal, even my one & only (so far) RHINO1.0 can do that, means to allow for a bigger diameter of the pipe further up the spral.
What version of RHINO did you use ?
thx and kinf rgds.
franz
i use rhino for mac but this can be done in all rhinos
• draw the centerline curve of the tornado
• use the Spiral command
• choose the command line option ‘Around Curve’
• select the centerline curve as the curve
• click on the bottom end of the curve then set the radius/diameter for that portion
• click on the top end of the curve then set the radius/diameter there.
options are also available within the command to set the number of turns and direction of spiral.
draw the centerline curve of the tornado
• use the Spiral command
• choose the command line option ‘Around Curve’
• select the centerline curve as the curve
• click on the bottom end of the curve then set the radius/diameter for that portion
• click on the top end of the curve then set the radius/diameter there.
All the above done… but that’s the result:
I call it “Spiral meltdown.”
What I need, is a progressive Spiral, that allows for a bigger diameter of the pipe in it’s “upper” part, without “melting” it into the “torus”, that’s below it.
ergs,
franz
that’s a matter of choosing the right pipe diameter on each end of the spiral… in your picture, it looks like the starting diameter is too small and the end diameter is too large…
i can’t think of a super simple way to accomplish it right now but i’ll think about it some…
@anybodyElse – maybe someone else has already thought about it?
Well… YES.
Or the other way round:
The starting diameter is quite right… meaning that…
the “pipe”, which is in real life supposed to be a torus, sheetmetal wrapped around that Spiral. curve…which makes it a “balloon”, that’s filled with Hydrogen… is an “integer body”.
rgds,
franz
yeah, that’s possible too in which case the spiral is spiraling at the wrong pitch…
either way, there’s a bit of a complex maths thing going on in order to get the variable spiral pitch&turns to coincide with the variable pipe diameter.
it’s possible there’s a little trick to getting all these things to line up properly but i haven’t had the ah_ha moment yet.
Take your time… :-)))
blessings,
franz
Is that what you want?
Vittorio
i think so except there would be no spaces (or overlaps) in between the pipe revolutions
?
yours looks like it’s on the right track though… or the spacing looks mostly consistent… how did you do that?
Good Morning*** Vittorio 
***CET.
And YESSIR, that’s exactly what I want !!
Now HOW did You do that, and what Version of RHINO ??
Ciao bello,
franz
The Video shows like make a spiral with variable pitch. The second image shows like make a pipe with sweep1.
I use Rhino V5
Ciao Vittorio
<img
If i use pipe the result is the picture below
Brilliant! Thanks Vittorio! --Mitch
Hello Vittorio 
Thank you very much for Your eplanation, and also for the magnificent manner in which You visualised it.
kind regards… Ciao…
franz
if the spiral doesn’t vary in pitch, i suppose an easy way to do it would be like the following.
spiral:
draw a line from the endpoints of the spiral to the perpendicular point of the next rotation:
using _Pipe, set the centerpoint on the ends of the pipe and the radius at the midpoint of the lines drawn in the last step:
(not completely sure this will always work out properly… just an idea that popped into the head without further thought/testing)
Hi Vittorio
What commands did you use to make the spiral with variable pitch, as you show in the video ?
I would like to spiral around this surface.
Thanks
Hans Henrik
I think I found the command: InterpCrvOnSrf
But I couldnt pull the curve around, outside the surface, as you do in the video - I had to rotate the view, while pulling the curve. Thank god I have a 3Dconnexion mouse !! 
