Hi guys, why if i make curve in shape of number 8, then i apply curve modifier to pipe (which is long cylinder) then i apply boolean modifier (union) to cylinder and box, why it doesnt work?
The box disappear, or the effect of boolean doesnt work as expected, its only “flat”.
It seems to me that it is problem if the curve intersects itself.
I tried to go in edit mode and recalculate normals of the pipe, but no effect…
Check the img
Thx.
Are you going for the prize of worst screenshots ? Step 3 is just a grey rectangle with some writing !
What are they tiny and miss out huge portions of the remaining blender interface ?
What box are you talking about?
What modifier settings ?
Mesh details ?
What result are you wanting to achieve ?
Why not just cut to the chase and supply a blend file so we can all see exactly what you can
Step 3 is the box, as written on the image…
unfortunately, this isn’t currently a super easy thing to solve. If you wait until Blender 2.72 comes out it will be much easier 
which should be a week or two away. Basically the problem is that your infinity shape is self-intersecting so the boolean modifier is confused and doesn’t know which parts it should consider the inside and which parts are the outside of your shape.
there are however easier ways to go about trying this than using the curve modifier. instead, use the curve bevel controls and then convert the curve to a mesh. it will be a better starting point.
You could manually remove all of the geometry inside of the intersection and then rebuild the surface in that area to make it watertight. ooooor you could disassemble your curve, make each part a watertight mesh, use the boolean modifier to union them, and then finally union that shape to your cube. That would look something like this: http://cl.ly/3T2s1M2W3139
btw, the feature that will make this easier is the “editmesh intersect” here: http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.72/Modeling
oh and looking at your images, it looks like you also need to make sure your curve is cyclic:
and convert your curve to a mesh object:
hello atartanian, thank you for your explaining reply :). i thought that… that the problem is, if the curve intersects itself…
well, ok, i hope they will release the new version soon then 
thank you for your additional responses too, will look on it.
your are good, thx.
L.
Btw same problem happens, if the curve is only O shape :), or simply just closed, or as you say cyclic.
Will try only the curve solution then.
L.
Atartanian, you were right… much easier with only beveled curve… works as expected…
Attaching image, also for moderator Richard, to see what i wanted
Thx.
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