Infill without overhangs, bridges, or crossings
Often times the main point of infill is not to add strength to a model but simply to maximize the chance of a successful quality print.
In these situations, when printing a large model in PETG, I want to avoid overhangs, bridges, or crossings (where two lines cross in a single layer) in the infill, to minimize the chance that the infill is a source of problems.
It seems the only choices in this case are:
Concentric, Honeycomb, Hilbert Curve, Archimedean Chords, and Octogram spiral.
Of these, only Honeycomb seems like the a good choice to me, since the rest can be sparsely connected.
Are there others I should be considering?
RE: Infill without overhangs, bridges, or crossings
I could be wrong, but I don't think any of the infill patterns cross themselves on the same layer. They do typically cross the underlying layer though. I can say that I have never had a print fail due to infill. If you're worried about bridges in the infill (when the infill layer bridges the underlying infill layer), increase the infill density. However, generally, I don' think this is a significantly issue unless you make your infill density very low.
RE: Infill without overhangs, bridges, or crossings
Grid, triangles, stars and cubic all have intersecting lines, at least as implemented in the current version of Prusaslicer. You can verify this by examining a single layer in the slicer.
With PLA I never have infill problems, but with these choices the infill gets a bit messier when I print with PETG at a fast speed and/or at lower temperatures. I suspect that t;hese intralayer collisions can also contribute to globbing of PETG, which is a problem that I see discussed occasionally.
RE: Infill without overhangs, bridges, or crossings
Gyroid is good for PETG as it doesn't cross itself and each layer rotates slightly. The only issue is its movement intensive so can cause memory problems with larger models iirc. Its currently being tweaked at the moment to sort that out though so it should be even better in future releases.
RE: Infill without overhangs, bridges, or crossings
@neophyl
No intersections is a good feature of gyroid. It does have a lot of small bridges (and overhangs), making it a less conservative choice for fast PETG printing, I guess.
RE: Infill without overhangs, bridges, or crossings
No love for rectilinear or line infills? These also are non-crossing within each layer, they cross on alternate layers. (But if you don't have your max volumetric flow setting correct you can run into under extrusion issues because they have among the best chances of actually accelerating fully...)
Of the infill types that cross within each layer, cubic has an interesting property. This is the only one (AFAICT) that creates individual sealed chambers both horizontally and vertically. So if you are printing something that needs to float (for example boats or pontoons) any accidental leak will be better contained.
See my (limited) designs on:
Printables - https://www.printables.com/@Sembazuru
Thingiverse - https://www.thingiverse.com/Sembazuru/designs
RE: Infill without overhangs, bridges, or crossings
I've found rectilinear to not work too well for PETG; it doesn't like the unsupported areas on each alternating layer. At least, with the PETGs I use, I end up with globs building up on the nozzle that I don't get with PLA prints from these areas curling.
RE: Infill without overhangs, bridges, or crossings
Rectilinear and line both have "bridging"---kind of----in the sense that they lay down lines on top of lines 2 layers down.