Drawing a 3D curved line

[Kenny Koala]

I need to draw a line that curves through all 3 Cartesian co-ordinate planes at the same time. ie. X,Y & Z planes. This is for a fan blade. My problem is, AutoCAD does not seem to allow this in any of its line drawing formats. 3D polylines can only be straight. 2D polylines can be curved but only in 2 planes. Can anyone help with this please?

[rkmcswain]

You can define a UCS from the 3 coordinates that make up the curve, then draw an arc.
Will this work for you?
See also: http://www.eng-tips.com/viewthread.cfm?qid=1217

[Kenny Koala]

Thanks for the suggestion but no. The curve I need to draw does not look straight from any perspective you look at it. Sort of like a helix but without a constant radius (French curve type of thing). If you look at a domestic pedestal cooling fan blade, you will see what I mean.

[vmichl]

You can try SPLINE or approximated (calculated) 3D Polyline.

Vladimir Michl, www.cadstudio.cz www.cadforum.cz

[Kenny Koala]

Thanks Vladamir. I will give it a try.

[Wanderer]

Just curious if this worked for you?

[Kenny Koala]

Just curious if this worked for you?

Hi Wanderer,
None of the above I am afraid. I have resolved the problem albeit in a long way around. I had to draw the curve in plan, then also in side elevation, extrude both as surfaces so they intersected each other then trace a 3d polyline onto the resulting intersecting line. I could then use the resulting curve as my sweep line. Seems to be the only way. Looks like a hole in AutoCADs modelling ability.
Thanks for the enquiry

You have to plot a series of points along the desired curve, then spline/knots/uniform, then select the points and enter upon completion.