Hi everybody,

First of all I'm a C4D user, despite I bought Moi3D years ago I'm not very confortable with, because I rarely need it. Anyway these days I need it for a special task and I've got a small problem :p

I have to take a plate (1m x 12,50m) and twist it on a spiral of 2m diameter. I succeed in a certain way but the profil view shows a very strange concave effect and I don't now how to avoid this…

Thank you for you help ;-)

Hi iolofato, it helps a lot if you can post the .3dm model file with your objects in it instead of only a screenshot. That then makes it possible to do stuff like zoom in and examine your objects closely which isn't really possible to do with a screenshot only.

- Michael

My guess is that the concave effect might be from some twisting like this but it's hard to tell without being able to examine the geometry:





- Michael

Thank you for you're quick response ;-)

Yes you're right, polygons are following the spiral perpendicular to it (which is better) but then generate a concave effect, which wrong in reality… I mean this is a project for a sculpture made with 2 metal plates and I have to deliver a clean model. Is there a way to achieve this ?

I'll post the 3D model…

Absolutly straight lines for me :)

A vertical line Sweep on helix...
(render free simlab Composer Lite (Max 1920 * 800)

Sorry crossing post (and not use the Flow function - don't now you have volumes to drill)

Here the export only triangle OBJ



Apparent deformation is perspective

Hi iolofato, well for the surface shaping to be correct you can do that by creating a vertical line for your sweep profile:



Run Construct > Sweep, select the one helix curve for the sweep rail path, then set the Twist: Flat option:



So now you'll have the problem with your pattern being distorted. Maybe a good solution would be to make 2 versions, one with your "good for flow but with concave silhouette" and generate solids using Flow on that one, and use those to cut out from this straight sided one.

When you make the objects to use as boolean cutters, make them stick out some distance from the surfaces, don't make the cutting objects have overlapping surface areas with the base object.

Would that combination method be workable? I guess another possibility would be to incorporate a kind of italic text like slanting effect as part of the pattern flow.

- Michael

Hi iolofato, so yes the concave shaping that you're seeing is due to "ruling line twisting" like I was showing above (http://moi3d.com/forum/index.php?webtag=MOI&msg=10257.3)

It's a type of shaping effect you can get on a ruled surface (a surface made up of straight lines connecting between 2 curves) if the ruling lines are not restricted.

If you turn on your surface control points you can see yours is similar:



- MIchael

Thanks a lot to all of you, I'm sure your remarks will be really helpful ;-)

For build a same line distance "Flat" to Flow
you can Array Curve a Point along a curve (here an helix)
and cut the curve at the wished distance...