Helix between two known points

[trobinson]

I am hoping someone can help me out.

I have to develop helix geometry from survey data to find the correct spiral for a railing.  I have developed the two points that I need the helix to start and stop at, I have the diameter, and am trying to develop the helix based on the "height and revolution" method.  As you can see in the attached model, I have created a 3D sketch to develop the driving dimensions.  The parameter (Rise_Run1) will drive the height of the helix. The parameter (Rev_Run1) is calculated from the angle between the two points div. by 360 to develop the number of revolutions.

Unfortunately things are not working.  Inputting the parameters into the "height" and "revolution" fields produces the following errors:

   A solver could not be found for a constraint network.
     A cyclical constraint dependency was detected.

I am hoping someone can point out my errors or provide me with a better solution for developing a helix with a known diameter that begins and ends at two known points.  Any tips are greatly appreciated.... I am in a bit of a bind!

Thank you.

TR

Inventor 2013

[trobinson]

...

Or I suppose I could stop being a dummy and project the line of the angle to the curved plane.  Although this result does not seem to be exact?

I would still like an experts' opinion on the question of the helix, and some pointers on the correct workflow for what I am trying to accomplish.

_TR

[bob_holland]

TR,

Would you be willing to post SurveyImport_.ipt?

Please post a screencast of what you are doing.

When I used the values of your parameter, I was not able to get it to fail.

With a screencast I might be able to better follow what you are working to accomplish.

Bob Holland

Autodesk Product Support

[trobinson]

I would be happy to. As far as a screencast, is there an easy way to create/post that?

[bob_holland]

TechSmith Jing is a good option:

http://www.techsmith.com/jing.html

Bob Holland

Autodesk Product Support

[swhite]

If you run windows 7 it comes with Snipping Tool (in the Accessories folder on Start Menu) which as a basic one isnt bad.