hi everyone,
given are two blue helix curves with an offset of ca. 20cm, is it possible to smoothly connect them with another curve starting from the bottom point of the inner curve (red point) and ending at the top point of the outer curve (yellow point), while roughly keeping the curvature of the green curve?
thanks in advance
From a viewport perpendicular to the helix axis, and with Project on:
Move the end of the green curve to the red point, rotate the green curve about the red point so the other end aligns to the yellow point, then scale2D the green line, using the red point as the base, so that other end joins the yellow point.
With your proportions the new green curve will have a radius extremely close to the old one.
The green curve will however stray outside the blue ones which, I suspect, means it will fail to meet an unstated criterion…
It is mathematically impossible to create a helical curve with a circular profile that connects these two points without crossing the blue lines.
But that osculation may not suit, so how about this?
To get there you need to go back to 2D drawing. Draw three arcs on the base plane under the blue and green lines (don’t try the shortcut of projecting your lines, the last thing you need is all those control points).
Then select the end control points of the middle line and drag them to the appropriate ends of the outer lines. Select the middle line and extrude it upwards, higher than your helix to create a surface and pull the green line onto it:
To finish, hide those construction artefacts!
HTH
Jeremy
a quick&dirty way is:
use Loft to form a surface between the two blue curves.
use InterpCrvOnSrf, select the surface, click on yellow point then second click on the red point. (you may have to fiddle with the cursor a bit in between the clicks to make sure it knows follow along the desired path)
then delete the surface if you don’t need it
Use a non-planar spiral.
Spiral command
Direction of the spiral axis same as the helix axis.
Base of the spiral axis same as the helix axis.
Turns mode
Number of turns of spiral same as number of turns of helix.
First point of spiral bottom of the inner helix.
Second point of spiral top of the outer helix.
Thanks very much!!
