general question about determining feature sizes of meshes

I suspect I already know the answer to this but I thought I would ask.

When designing for 3D printing, there are a few unique things to keep in mind:

  1. overhangs: for several types of 3D printer, some stuff like “bridges” or features that jut out into space can’t be printed right. Since the model is built starting from a bottom layer and moving up, and using a moving extruder, things that hang downward, or straight out, can’t be printed right, without support layers.

  2. feature sizes: 3D printers have minimum resolutions that they can handle. They also have minimum cross-sections of features that they can produce.

I am wondering how hard it would be to write a script that checks for overhangs and feature sizes.

for #1 it would check whether any part of a mesh was considered an overhang.

for #2 it would have to check whether any part of the mesh had a cross section of less than X, where X is the minimum feature size of the printer.

I assume these things are hard to do, but are they REALLY hard to do, or just sort of hard to do?

What would be great is a tool that highlights or warns the user as they’re modeling, so they can avoid those problems before creating dependencies on invalid design features.

at least one 3d printing company has an online tool which highlights critical areas of models, not sure how they do it. In Blender I would expect it to be very difficult in terms of the involved math. But maybe there’s a way to sort of run a physics simulation on your model. Overhangs would bend down and in comparison to the original vertex locations, you could tell how critical it is… But it’s just a crazy idea :wink: