Hi Ditto,

> Strangely, only a couple of the polygons are piped, the others won't. I can't see a difference
> between them, but something is not working.

It's difficult for Sweep (which Pipe is based on, it's just like a macro that does sweep with a circle as the profile curve), to handle path curves that are warped in 3D space (meaning not planar) and also have sharp corners in them, which is what many of your path curves here have on them.

The way sweep works it does each segment of a sharp cornered path individually and then tries to extend the segments and cut them with one another to form mitered corners. That "cut against each other" step becomes difficult on non-planar warped paths because the sweep along a curved path generates a kind of twisting and banking effect of the profile as it travels along the path and so it's easy for the surfaces to not actually cleanly intersect with one another. Check out here for a more visual explanation on the difficult part of this: http://moi3d.com/forum/index.php?webtag=MOI&msg=4937.4

It should work ok if your path is made up of all line segments instead of slightly bent curves though - when segments of the path are lines it's able to cut each piece by a plane to make the miters.

Your paths are so barely curved that it would probably not be a very dramatic change in shape to have all straight lines for them rather than the very slight curves that you currently have.

The ones that ended up working ok for you were planar or happened to be very very close to being planar.

Hope that explains some of what you ran into.

So to fix it you would either want to have all straight lines on your paths or probably do it all on a flat planar pattern and then do a flow on that to apply the whole set of pipes onto the curved surface rather than building pipes in the curved position to start with.


> But if I wanted to have a square pipe or an I-beam instead, what command would I use?

You can use Sweep for that - it's the general version of Pipe, and in fact Pipe is not anything more than drawing in a circle and doing sweep.

Check out here for some examples:
http://moi3d.com/forum/index.php?webtag=MOI&msg=5407.6
http://moi3d.com/forum/index.php?webtag=MOI&msg=3431.4
http://moi3d.com/forum/index.php?webtag=MOI&msg=4578.3

- Michael