Law curve along an existing curve

[BOPdesigner]

In NX 6 I am using a law curve to create a 2D planer spiral.
x(t) = (r0+r)+cos(n*360*t)
y(t) = (r0+r)+sin(n*360*t)
where r is a function of t and n is the number of turns in the spiral. z(t) in this case is 0

Now, I want to superimpose a sine wave on the spiral where the amplitude of the sine wave varies in z. I can to this but using the same equations for x and y and then just add a z(t)= A*sin(n*360*t) but the problem is this sine wave wavelength now varies as r increases from x and y. I want it to be constant along the length of the spiral. In otherwords, take the classice sine wave as a function of time, then wrap the straight line time axis into your spiral. I can't figure out which options to pick to make this curve. When I select the "by law curve" for the new subtype for the x and y and then specify my z as an equation subtype no curve gets created. Any Ideas?

 

[mmauldin]

Something like this?

 

[BOPdesigner]

Nope, that is the same as what I have. Notice that your wavelength (or period) starts out small at the center of the spiral and then gets larger as you progress to the end of the spiral. I want the period to be constant as you progress from start to end on the spiral.

 

[Toost]

I think that you mis-interpret the law curve by law curve option,
It will not "default wrap to" a curve but rather read the "X" (or Y or Z) value from the selected curve.
If in case your X and Y functions would have been circular, the law curves to follow would have looked like the ones in the attached picture.
Regards,
Tomas