I am trying to find the intersection of a a helix with an irregular, free flowing tube.
The tube is created with a series of profiles along a curve and a sweep1 selecting all these profiles.
The next step is then to create a helix that intersects a single point along each length unit of the tube.
The file contains 1) an example of the expected intersections with a simple cylinder 2) a trial to obtain the required result. The trial is not successful as it generates multiple curves and not a single curve…
How could a “centroid” curve to helix around be created?
How can the projected line be reworked/rebuilt so that it 1) still interects the surface 2) has smoother transitions?
Finally, to extrude along this curve (a rib or a boss in the tubular surface), i though about using pipe, then bolean commands. Is this the most efficient method?
I’m not sure I understand your problem very well from the description given. I am guessing you are creating the helix using the AroundCurve option, that the curve is the rail used in the sweep and that the curve is on the surface of the tube.
If that is the case, I suggest you develop a curve through the centre of the tube and use that to produce the helix. One way to produce that curve is to create the area centroid of each section (command _AreaCentroid) and interpolate the curve through those points. You probably need to create extra sections to keep the curve central.
A helical surface created around a central curve should produce a single intersection curve with the tube.
Here is an example done that way, with helices in both directions:
You are right on the aroundcurve; and that the curve and the helix curve are used for the sweep2.
I checked your file and this does indeed work.
How did you extract the sections?
Is there a command like ExtractIsocurve that allows to extract multiple cross-sections of a polysurface?
I used the Section command, because it ensures the curves are planar (necessary for the area centroid command) and it allows you to orient each section to be perpendicular to the tube.
If you had a straight tube you could use the Contour command to generate a series of sections in one hit, but that won’t work here where you need to follow the bends.
