Pipe Command Causing Problems

I created the yellow line along the top surface to pipe around. I keep getting erratic results, as you can see. Some things trim, others don’t. Thanks, rex

Hi Rex - non-planar miters can, usually do, cause problems for Pipe - it looks like the hard corners are planar but there is a kink in the curve where the top and bottom flats hit the slope between them - my guess is that this is meant to be tangent on the part but is not - can you post the file or send to tech@mcneel.com?


In line with what Pascal said, if you have three points planar for the non planar curve leading up to the corner it should trim for you like this…

Tender Step copy.3dm (337.5 KB)

Here’s the file. I’d like to understand more about the kink you mentioned. Not sure exactly where it is, and more importantly, how to get rid of it. thanks much

Hi Rex -

These locations (both sides) look like you intend them to be smoothly, at least tangent, continuous but there is a slight crease (3.5 degrees) between the surfaces there.


Did you use some command to determine it’s 3.5 degrees?
What’s the best way to rectify that (bring it back to tangent)?

Hi Rex - I actually just checked the continuity of the segments of the curve you have sitting there (GCon command, Analyze menu > Curve > Geometric Continuity) - I guess these are extracted isocurves? That is not necessarily an exact measurement of the surface kinkiness across the edges but it gives us an idea. To measure more exactly at any location on the edge, you’d have to draw surface normals there for each surface (Line > Normal) and measure the angle between, but there is no need to go to those lengths - it is visibly not tangent (BTW, see also the Zebra command) so if it should be, lets fix that. I’d step back a bit and see how you got to the top edge curve(s) to begin with and tune up that process.


Pascal, to create those surfaces…

  • Used curve through points to create the outside curve in the x-y plane. Started the curve in the horizontal region at each end.
  • Created inside curve using offset command.
  • Extruded curve into solid wall
  • Used curve through points to create curve in the x-z plane and trimmed the wall with it.
  • Used the command that turns closed curves into surfaces to create the top surface.

See any issues with that process? I’m thinking that in the first step is where I lost the tangency because I probably wasn’t paying that close attention to it.
I’m wondering if I need to start at that point aka start over to fix?

Hi Rex - it’s hard to say without knowing what the constraints are - it looks like, maybe, you can make the curve that makes the top profile shape (in side view) as one clean planar curve and use it to either extrude then trim, or WireCut the full box shape.


I’m thinking that now I see what the issue is, I’m going to start over, rather than try to keep fixing this thing. Net result is that I’m learning a lot. thanks much

Pascal, I seem to remember that there was a set of commands that would allow you to align a couple of curve ends to 180 degrees if they were a little off. Also, isn’t there a command to regenerate control points for a curve so that they are more evenly spaced and less erratic? Can you remind me of those if they exist?

thanks, rex

Hi Rex - the Match and Rebuild commands should help for these. Note both will change the shape of the input.