I want to do a Fibonicci spiral, raised in the middle

drasaid

It seems absurd, as this is not a complicated shape, but I have had a rough time making it. I want a Fibonnacci spiral about two feet high in the middle and lowering as it gets bigger: that is a right triangle with the 90% corner on the ground in the center, then the smallest angle at the outermost point of the Fibonacci spiral. I thought all I had to do was make the spiral and then lift the middle, but NOOOOO. I suppose I could make a small 'handle' and pull up the center point but so far I have had no luck. I will have another spiral (flat) on the ground (the whole thing is a design for a planter, and is to be made of fabric.)
Can anyone help me here? I'd be very grateful.
s

mac1

@drasaid said:

It seems absurd, as this is not a complicated shape, but I have had a rough time making it. I want a Fibonnacci spiral about two feet high in the middle and lowering as it gets bigger: that is a right triangle with the 90% corner on the ground in the center, then the smallest angle at the outermost point of the Fibonacci spiral. I thought all I had to do was make the spiral and then lift the middle, but NOOOOO. I suppose I could make a small 'handle' and pull up the center point but so far I have had no luck. I will have another spiral (flat) on the ground (the whole thing is a design for a planter, and is to be made of fabric.)
Can anyone help me here? I'd be very grateful.

Not sure why you are using the Fibonacci series?
Once you pull it up then what? What is the bottom dia you want and how many radial points are you using to create the curve?
Have not done this yet but the suggestion is;

Establish the number of radial points you want to use. do you want to go around 360 degs?;
Use the series then to establish the radial length of each one of these segements, for example
f0=x,f1=x,f2=2x,f3=3x etc where fn =ax where ax equals the desired radius and you know what x is now once you have each of these lengths establish then move each segment up in proportional distance of your desired axial height. IE fo will be moved 24", fn 0".
Hope I understand your problem and this is not too confusing, will try and make model for you after football game.
PS I have tried moving by pulling up center point of a 2d curve but the curve stays planar but tilted by the height pulled.

EscapeArtist

You could try Curve Maker. I don't think it does Fibonacci spirals, but it does do Archimedes and Bernoulli spirals. If you absolutely need a Fibonacci spiral, maybe someone here can help you figure out how to pull the center up - I didn't figure it out, but I didn't spend a lot of time on it either.

mac1

@drasaid said:

It seems absurd, as this is not a complicated shape, but I have had a rough time making it. I want a Fibonnacci spiral about two feet high in the middle and lowering as it gets bigger: that is a right triangle with the 90% corner on the ground in the center, then the smallest angle at the outermost point of the Fibonacci spiral. I thought all I had to do was make the spiral and then lift the middle, but NOOOOO. I suppose I could make a small 'handle' and pull up the center point but so far I have had no luck. I will have another spiral (flat) on the ground (the whole thing is a design for a planter, and is to be made of fabric.)
Can anyone help me here? I'd be very grateful.
s

My cut at your planter drawn per my suggestion above. Used coefficients to 55, 5" base rad, and height of 24", and then radial array copy around base to make total
http://sketchup.google.com/3dwarehouse/details?mid=731759d2a0ace698ab9c83967811b1f7

mac1

@mac1 said:

@drasaid said:

It seems absurd, as this is not a complicated shape, but I have had a rough time making it. I want a Fibonnacci spiral about two feet high in the middle and lowering as it gets bigger: that is a right triangle with the 90% corner on the ground in the center, then the smallest angle at the outermost point of the Fibonacci spiral. I thought all I had to do was make the spiral and then lift the middle, but NOOOOO. I suppose I could make a small 'handle' and pull up the center point but so far I have had no luck. I will have another spiral (flat) on the ground (the whole thing is a design for a planter, and is to be made of fabric.)
Can anyone help me here? I'd be very grateful.
s

My cut at your planter drawn per my suggestion above. Used coefficients to 55, 5" base rad, and height of 24", and then radial array copy around base to make total
http://sketchup.google.com/3dwarehouse/details?mid=731759d2a0ace698ab9c83967811b1f7

BTW it sees to me you would be better to ues the follow me tool. Why not??

chrisjk

Not entirely sure I have understood exactly what you want but the plugin k-tools can be used to draw a logarithmic spiral like this

Then you can use the Control points plugin to add points like this

and then you can pull these up with the move tool - I just pulled up the one in the centre.

pilou

If you consider than arcs is a good aproximation it's not a big deal to draw it by hand

PS Why not put an image (a schema)of what you do want?

mac1

@unknownuser said:

If you consider than arcs is a good aproximation it's not a big deal to draw it by hand

PS Why not put an image (a schema)of what you do want?

Don't think the issue is drawing the fibonacci curve but extending that to the planter desired. The generating function can be found in many text books and I assume that was drawn correctly in the first place but the pull up failed. How does one go from the curve to the planter is the real question per my above disussion. With the many line segemnts this gets to be a head ach unless one can find a plugin that will do the repetitive task quickly and is the reason for the use of the small number of line segs above.
FYI the generating function is 1+s+2s^2+3s^3+5s^4+8s^5+.... +55*s^9...... which is what I tried to use but made a mistake. Used coefficients only so the approach needs to factor that into the model.

ely862me

Is this what u re looking for?

All the best!

Elisei

Fibonacci spiral.jpg

drasaid

Thanks. I really did not phrase it right - I am trying to make a good herb spiral.
http://www.mitra.biz/howto_herbspiral.htm
Everyone is hepped up on making them out of rocks, but frankly they don't look like spirals. I want a nice snailly spiral! The one Elisei did comes closest, and I'm going to try and do it.
Unfortunatly, I have NO idea how to plug in a plug in so K-tools is just beyond me at the moment. The other planter drawing is nice but way beyond what I am trying to make-just a wound up fabric triangle sewn spiral. I'm gonna fill it with dirt and herbs.
Thanks.

mac1

@drasaid said:

Thanks. I really did not phrase it right - I am trying to make a good herb spiral.
http://www.mitra.biz/howto_herbspiral.htm
Everyone is hepped up on making them out of rocks, but frankly they don't look like spirals. I want a nice snailly spiral! The one Elisei did comes closest, and I'm going to try and do it.
Unfortunatly, I have NO idea how to plug in a plug in so K-tools is just beyond me at the moment. The other planter drawing is nice but way beyond what I am trying to make-just a wound up fabric triangle sewn spiral. I'm gonna fill it with dirt and herbs.
Thanks.

It always amazes me what one has as a idea of a problem and what it really is. So my question now becomes once you have the spiral drawn, what ever type it is, then what? Perhaps you should change your focus to how one lays out the spiral in your herb garden. Your " I am trying to make-just a wound up fabric triangle sewn spiral" still has this pea brain confused but, if you consider an involute of a circle is a spiral which you could very easily lay out in your garden I would suggest that. You can find this book in Google books and because it is out of copy right you can freely down load it. The title is: "Practical Geometry for the Architect and Engineer". Article 172 shows how to geometrically lay out this type of spiral in your garden. Concept wise consider unwinding a string which was tightly round around a drum and one just marks points as you go around. Then staking your herb " tube" to those points will give you what you want I think?

BTW where did the Fibonacci curve idea come from??
For the pligin installation they go in the SU plugin folder and usually there are directions with the plugin and you can also watch some of the youtube videos on this subject. Here is a starting point http://www.youtube.com/results?search_query=Sketchup+pluguins&search_type=&aq=f

mac1

@drasaid said:

It seems absurd, as this is not a complicated shape, but I have had a rough time making it. I want a Fibonnacci spiral about two feet high in the middle and lowering as it gets bigger: that is a right triangle with the 90% corner on the ground in the center, then the smallest angle at the outermost point of the Fibonacci spiral. I thought all I had to do was make the spiral and then lift the middle, but NOOOOO. I suppose I could make a small 'handle' and pull up the center point but so far I have had no luck. I will have another spiral (flat) on the ground (the whole thing is a design for a planter, and is to be made of fabric.)
Can anyone help me here? I'd be very grateful.
s

drasaid
If you are still interested here is my final cut to your original posting question http://sketchup.google.com/3dwarehouse/details?mid=6085c7704024dc9aab9c83967811b1f7.
I was lazy this time and down loaded the spiral form the web ( also corrected error per my above discussion) or you can use the same one Pilou showed above. This came as a .png and then the arc tool used to create the skp model by basically tracing. The radius was then scaled to approximately 32" and then using the sandbox tool to drape the arc on a cone 72" dia by 24" ht with its center close to the arc center. note this does not require any new plugins. The sand box is part of the your SU installation. If it does not show under your tool bar drop down menu then go to windows, preferences and enable it under the extension drop down
have fun!

pilou

Maybe take a look at this?

Shape Bender by Chris Fullmer And you have a "courbette" in Bezier tool by Fredo6!
And you can use after Fredo Scale for deform it with tapered tool for have a triangle form spiraled of the all volum!
Just erase face bottom if you want only a line!

[flash=425,344:11lvpmyh]http://www.youtube.com/v/tGHTIOMm_34&hl[/flash:11lvpmyh]

drasaid

due to the dread Caliche soil here in Austin: it shifts everything so what you put down does not stay there. A good fabric base will just slide about on the ground (and hopefully the sides will stay up).
I am sorry I was not more clear about stating my needs.
I need to make one and set it up, then find out just how practical it is. Thanks for the help, I will try the spiral-on-a-cone one (sounds like something you get at Dairy Queen.)