Hiperbolic spiral

[ovum]

Hello my friends .
I have problem with a ploting a hiperbolic spiral fram curve equation in creo.
here some theory :
https://en.wikipedia.org/wiki/Hyperbolic_spiral

And now : when I'm trying write something like this
Cylindrical system --->r=1/theta z=0 or
Cartesian x=t(cos(a)/a) y=(tsin(a)/a) z=0 a=(0...1) but then I have error message but have no idea why.
Could someone help me with that ?

 

[design-engine]

Cool. Any takers?

 

[ovum]

C'mon boys(and girls) ,dont be ashamed.I believe you know how to write that hells equation correctly

 

[zpaolo]

Just a rough guess: if a starts from 0 then cos(a)/a is gonna be a 1/0, which is not good Have you tried adding a very small number like 10^-12 to "a" in order to avoid having a 1/0 situation?

 

[zpaolo]

I did some tests in MathCAD with the notation used on wikipedia (x=a*cos(t)/t) and with t lower than 1 the value is very very big, a nice spiral is obtained with t ranging from 1 to, say, 30. Still have to make it work in Creo

 

[zpaolo]

I got it. So Creo is using degrees as arguments of the Sin and Cos operations, therefore you have to be careful in how you use the t parameter. With this formula:

a=100
x=a*(cos(t)/t)
y=a*(sin(t)/t)
z=0

and t ranging from 100 to 30000 I got a nice curve, of course if you want to be correct you should scale the "t" at the denominator by PI/180 because in this case t is in degrees.

So if your formulas are like this:

x=a*(cos(t)/(t*3.14/180))

you will have the exact results as in the formulation of Wikipedia (assuming t is in radians on wikipedia and in degrees in Creo). Let your "t" start from 90 (90 degrees) and the curve will start from the positive side of the Y axis, and let it go to 90+n*90 where "n" is the number of quarter turns you want it to span.

The smaller angle you can start from is not much below 45 degrees otherwise the curve will fail. Sorry but I can't upload images :/

 

[ovum]

Thank you very much.Of course that's work perfectly .
Thank you !

 

[mgnt8]

Let's see it. Can you upload the part?

 

[zpaolo]

Sorry I can't upload anything from my work machine :/

 

[mgnt8]

Excellent work, thanks for figuring this out.

The equation didn't work for me at first, but I eventually got it to go through. Must be some kind of bug in this date code