cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Showing results for 
Search instead for 
Did you mean: 

Community Tip - Visit the PTCooler (the community lounge) to get to know your fellow community members and check out some of Dale's Friday Humor posts! X

Logarithmic spiral in Creo 2.0

ptc-5480261
1-Newbie

Logarithmic spiral in Creo 2.0

I am trying to create a logarithmic spiral defining it with an equation, but I can't get it to work!

I found a formula on another forum (for ProE) and copy/pasted it into the equation window.

theta = t * 360 * 2.2

a = 0.005

r = exp (a * theta)

The result is "Feature failed to regenerate". Creating ordinary spirals gives no problems, but adding ln, x^ or exp functions gives me problems. I think I miss some basic programming skills here.

Any suggestions how I get going?

Thanks, Jeppe.


This thread is inactive and closed by the PTC Community Management Team. If you would like to provide a reply and re-open this thread, please notify the moderator and reference the thread. You may also use "Start a topic" button to ask a new question. Please be sure to include what version of the PTC product you are using so another community member knowledgeable about your version may be able to assist.
8 REPLIES 8

Going for the easy solution: Are you using a cylidrical coordinate system? If not then theta and r won't affect anything.

Well, I'm on WF5/creo, and I've never seen "a", for cylinderical, it's r, theta, and z, in that order.

In this case "a" is just a constant, though there should be a value set for "z"

The equations are parametric equations (mathematical definition), relating each of the variables r, theta, and z to the parameter t.

Vary t from 0 to 2 in the dashboard, change to a cylindrical coordinate system, choose your csys, and then enter the following equation:

r=exp(5*t)

theta=t*360*2.2

z=0

Change z to z=exp(5*t) to get a exponential helix. Be careful with exponentials. A little bit can go too far very quickly and it will fail.

If you use the above equation, zoom in an out, it's like watching the intro of an old Dr. Who show.

Good observation on the range of values.

The original radius is from 1 (exp(0)) to about 52.5 (exp(0.005*1*360*2.2))

Ever watch Doodling in Math Class with Vihart?

Yeah, funny stuff. If you watch closely, you can almost see the pencil shrinking through the videos.

It works:-) Thanks guys!

Jeppe

Top Tags