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BHOoi16-Pearl
16-Pearl
November 26, 2018
Solved

Spiral curve with uniform pitch

  • November 26, 2018
  • 20 replies
  • 12319 views

Hi, I am trying to create a spiral curve with uniform pitch along its sweep direction. It seems Creo is only able to control the pitch along its trajectory spine, nothing else.  The pictures below show I am trying to create:

 

 

 

 

Creo4 part file attached here for your reference. 

Anyone has any idea how do I achieve this ? Thanks

 

 

Best answer by Patriot_1776

Ok, perhaps I was wrong-ish.  I re-tried an earlier method with a tweak or 2.  Actually simpler than the last one  posted and a lot more like what you want.  It MIGHT be possible to get it perfect, but  I got as close as I think you can reasonably get, with the large arc, middle linear distance (from point to point) being about .030" different from the large arc end distance, with the others falling in the middle.  The distances on the inner arc are exactly equal to 4 decimals.  I don't think you can possibly realistically get closer.  It's got a nice smooooth helix, which I like.

 

What's this for out of curiousity?

2018-11-29_trajectory_test2.jpg

20 replies

B
BHOoi16-PearlAuthor
16-Pearl
November 26, 2018

Creo4 part file

R
rburgess-21-Visitor
1-Visitor
November 26, 2018

Give this a shot: Datum graph

    B
    BHOoi16-PearlAuthor
    16-Pearl
    November 28, 2018

    Thanks, I will try it out.

    Patriot_1776
    Patriot_177622-Sapphire II
    22-Sapphire II
    November 27, 2018

    Can't open the file since I'm on creo 3.  In looking at the pictures instead of a model, I can;t tell what the cross section of the surface is, if it's circular or not.  But, it looks like you can get CLOSE, but not quite what you want.  Why? because the cross section of the helix is always going to be normal to the spine trajectory, when in reality you need it to change from one angle relative to the spine to another smoothly from one end, to the center, back to the angle at the start.

     

    So, how exact does it need to be?

    Patriot_1776
    Patriot_177622-Sapphire II
    22-Sapphire II
    November 28, 2018

    Also, even if you got it even closer, the pitch would ONLY be correct at the point where it intersects the 2 curves.  The rotation of the spiral along the trajectory would have to be nowhere near linear to make it work...

    B
    BHOoi16-PearlAuthor
    16-Pearl
    November 28, 2018

    can you model it out and share. It's hard for me to understand from your description above. Thanks in advance.

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