Orient cross section sweep 1 rail


I have a cross section I am trying to orient perpendicular to curve then do a sweep1 rail. I am trying to model screw threads. My helix is my major diameter, with the cross section snapped to the center of the root flat of the thread. What is the proper way to draw the cross section so it is oriented correctly on the curve, so when I run the orient command, I do not need to rotate it, or if I do need to rotate it, what do I snap off of so it is not just “eyeballed”. The picture shows that it is approximately 90 degrees rotated.


The next picture I was able to rotate it to the approx correct position, but not sure how to check to see if it is 90 degrees aligned to my curve. I tried the rotate command in the orient perp to curve command and rotating the cross section before executing the command, both seem to work but again not sure it is in correct position.


When running the sweep1 I get a twisted mess if I use road like or free form. After much messing around I found that if I hit the set axis button and choose the endpoints along the bottom straight curve, I think it will give me what I am looking for. What are the axis the set axis button is looking for?


Before I set the axis


after I set axis.


Thank you
sweep 1.3dm (1.6 MB)

One option that comes to mind would be to rotate the viewport construction plane so it lines up with your rail.
Then you can use Ortho and rotate the section to be perpendicular to the rail.
Remember to set your CPlane back to it’s normal orientation to avoid confusion later.
You can also add a name to the rotated CPlane so if you need to, you can easily get back to it later.

I’m sure others will chime in with other ways to do it.

Hello - I do not see your images here for some reason, but it looks like setting the axis parallel to X (i.e. the axis of your thread) gets clean results.


Yes I used John Brock’s method of setting cplane perp to end of curve. Then setting axis parallel to X. Thank you both.