Fixing Series: Error No.2 - Bad Edges

“Bad Edges, Bad edges, Whatcha gonna do, whatcha gonna do
When they come for you?”

Inspired by Bob Marley

Bad Edges, are next on the list of potential errors that could affect your 3D print. For those not used to the terminology these sound like the types of shady characters your parents warned you about. The kind that would hang around the back of the school smoking cigarettes. If left to their own devices Bad Edges, like true troublemakers, will also lead you down the wrong path.

Bad Edges, as touched upon in our introductory post on model errors are a result of faces or more specifically triangles, not fully ‘knitting’ together. They’re so very close together that the gap between them is potentially not visible to the human eye.

Perhaps worthy of an analogy to drive the point home: Friends Season 3 Episode 2 - “The One Where No One’s Ready”. Chandler places his hand in front of Joey’s face, it’s definitely an invasion of his personal space but crucially it isn’t touching and therefore Joey can’t get mad. In a similar vein edges can be excruciatingly close but if the software doesn’t understand them to be touching then it cannot react in the necessary way.

So close, but not touching.

There are two main causes of Bad Edges, the first is likely to occur during the course of modelling: copying and pasting of parts and multiple iterations can easily lead to elements being microscopically misaligned. Secondly, bad edges can appear during the conversion of models between softwares. Some software may read the same information in a different way: what might work in one modelling programme may not for another - especially when we refer back to one of the key objectives of working with 3D printing software as opposed to building design software: to have a watertight model.

If not dealt with, Bad Edges mean that parts of your model have non-manifold edges (in this instance meaning that edges are connected to less than one face). 3D printing software requires that all edges are manifold: connected to two faces only. In practice, if this rule is followed your model will be watertight and have a thickness throughout (so you don’t need to worry about the terminology, just the process).

Although we often won’t be able to see these bad edges 3D printing software does. It highlights these minuscule gaps and facilitates a clean up process.

We’ll lead you down the right path to 3D printed model perfection, get in touch.