# A shape of cubes has “dangling edges”

The shape I made consists of several hundred cubes (generated via Python), with some stacked on top of others, and all joined into one shape using Ctrl+J.
However, if I attempt to slice it using Skeinforge/ReplicatorG, it says that there are "dangling edges".

Is there any probable cause of these "dangling edges"? I have tried all of the Mesh > Clean up tools, but to no avail.

Thank you!

Here's a part of what the mesh looks like so far:

Edit: here's the .blend file:

• Did you select all geometry before proceeding to Mesh > Clean-Up tools ? Aside from that I think you should post some screenshots of mesh/-es in Edit mode and upload the file. – Mr Zak Mar 21 '16 at 20:47
• Welcome to the site. You might want to take the tour and review the help center. To provide for the best chance at getting help, you might want to post a copy of your ~. blend file to a site like Blend-Echange, and edit a link into your question. – brasshat Mar 21 '16 at 20:47
• @MrZak, I believe I did. Thank you for your advice; I posted a screenshot and uploaded the file. – 416E64726577 Mar 22 '16 at 2:01

Terminology may vary, but what Skeinforge/ReplicatorG is calling "dangling edges" refers to one specific type of non-manifold geometry. It is the kind where an edge is shared by more than two faces. In other words, this is bad:

It is an infinitely thin shared edge, because even though each cube has a volume, they are joined in a way that is impossible in physical reality. Imagine if you were to perfectly line up two tables so that their corners touch in a similar way - would you have one table or two? You would still have two tables, of course. With this kind of non-manifold geometry it would be analogous to having the tables inseparably stuck together at the corner where they touch, even though they are only connected by a few molecules. A 3D printer doesn't know what to do with that.

Here is another example - infinitely small corners. Or if you prefer, "dangling vertices".

So what are your options? Well, you can either separate them:

Or you can create a very small area where the cubes touch that joins their volume:

3D-printable edge connection:

3D-printable corner connection:

Now that you understand the nature of the problem, your challenge will be coding into Python a new way of generating your geometry that is manifold. Have fun. :-)

• Thanks so much for the explanation! When I keep this in mind, everything works perfectly. – 416E64726577 Mar 22 '16 at 23:04
• @416E64726577 Glad to hear! Happy blending. – Mentalist Mar 22 '16 at 23:10