Manifold objects in 3d printing

dzibarik

Can someone explain me what does "non-manifold" mean? for example if I have 3 separate objects grouped together into one object (but it's 3 separate parts really, 3 so-called shells) are they manifold or not? Netfabb shows no errors and says the mesh is ready but I'm confused.

Steve Schulze

Non manifold geometry is where you've got polygons which cause errors with your mesh. Things like internal faces, unattached edges, areas where you've welded vertices together that part of your model has no thickness.

Having different shells isn't non manifold geometry and will probably print ok, but in my experience you're usually better off making your models into one contiguous shape as it tends to make for cleaner prints.

dzibarik

thanks guys, I think it will go smoothly.

Rai

Jackablade wrote: »

you're usually better off making your models into one contiguous shape as it tends to make for cleaner prints.

Could you explain this a little further?

dzibarik

Rai wrote: »

Could you explain this a little further?

I think he meant that the object should be one object or different pieces joined together with boolean operations in 3D Coat or Modo. It's too memory intensive for me unfortunately, need to add more RAM.

edit: or you can model it as one piece but I'm too noob to model this as one piece -

Steve Schulze

Fusing it together in ZBrush with Dynamesh is usually the simplest option, although that'd be problematic with a piece as intricate as that one. Not exactly sure what I'd do with that guy.

Actually what I would do for a start would be to pull it together a little more so that more of the parts are in contact with each other to give it some more structural strength. Even then you'd need to be super-careful with it, particularly if you were to go with the higher resolution polymer prints which tend to be pretty fragile.

dzibarik

Frankly speaking I don't know what to do with this thing. I think printing it as one piece is a dumb idea in the first place. This should go on the drawer and I think the best way to do it is just glue it piece by piece. We'll see what we can do.

Rai

Sorry, I meant what types of issues will you see if the print has multiple intersecting shells.

CheeseOnToast

One way or another it will become a single watertight shell. If the printing company knows what they're doing, they should be able to do it at their end. Dedicated software such as Magics http://software.materialise.com/magics can fix up meshes pretty easily. If not, or if you want full control of the process you'll need to do it yourself.