I’m printing some Gridfinity bins for some drawers, and one of them needs to be quite tall to fulfill its purpose (18u, ~130mm). I took a shortcut and generated one from this generator using the default wall thickness and printed using Prusament PLA. This resulted in the walls falling in on itself, and my second failed print.
In hindsight, considering the wall thickness of 0.95 mm, this seems pretty obvious to me now. I want to give it a second go, but beef up the wall thickness and make sure there’s some proper infill between the outer walls to keep it stiff.
At the same time I don’t want to waste too much filament, so I want to hit a sweet spot of sufficiently thin walls and sufficiently low infill percentage, while avoiding another failed print.
Anyone have good experience with these kinds of prints that could give some input on a rough estimate for what I should aim for here?
I am using Adaptive Cubic infill by the way, but for no other reason than that has become my default infill pattern after some previous suggestions made here.
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Suggestions here and elsewhere to have no infill on tall structural components that will have large flat surfaces such as large boxes and bins is hilariously bad advice. Yes, “StReNgTh aCtChUlLy cOmEs fRoM ThE WaLlS,” but unless you plan to use an absurd number of perimeters and probably not even then, you absolutely need to have some infill to connect the inner and outer walls, otherwise they will be prone to warp and collapse in on each other. If your item will be as tall as you suggest, this is likely to happen before the print even finishes. Given the shape of the bottom of most Gridfinity objects, printing it entirely with no infill is impossible anyway. You can’t have a floor suspended in midair of any significant dimensions without infill underneath it to build on top of.
You probably don’t need much infill, probably only 5 or 10%. But it’s going to have to be there.
Don’t overthink it. I print these relatively giant Gridfinity drawer shells standing upright, and I use 10% gyroid infill, 2 wall perimeters, and 3 top and bottom layers. It works just fine and they’re perfectly rigid enough to stack at least four units tall (the most I’ve bothered to hook together to far) while loaded to the gills with probably more weight than is wise worth of knives and nuts/bolts.
I tried to print one without infill precisely once, and it collapsed and failed after about 30mm worth of height had been built up. This was with PLA which is the most rigid of the commonly available printable materials; the issue would be even worse with other plastics.
otherwise they will be prone to warp and collapse in on each other. If your item will be as tall as you suggest, this is likely to happen before the print even finishes
Yeah, this is what happened in the original, failed print.
I ended up making the model with 3mm thick walls, using two perimeters and 10% adaptive cubic infill (I sliced with gyroid as well, but it looked weird). Turned out great. I made some that were not quite as tall as well, with 2mm thick walls and 3 perimeters, which worked fine as well. It might have worked for the main boss here as well, but I’m not quite sure. The difference between the models was about 55 mm in height. The difference in material usage between the two options was negligible (< 10 g), with the infill variant coming out slightly lower in consumption.
I can’t speak for gridfinity bins in particular, but wall thickness can vary wildly depending on the purpose or look you’re aiming for. For medium-sized container (about the size of a closed fist), i would consider 1.50mm quite thin and wonky (but strong enough), 2.50 a good, solid width, and 4.00 quite chunky.
You can just print a few walls using the slicer and see what feels good, which is what I’d actually recommend you do.
Edited to add decimals
You want a 100mm box to have walls 25mm thick?
What are you trying to store?
Bins/boxes should have thicker walls and no infill. Real boxes don’t use infill unless the material lacks compressive strength, as in corrugated cardboard boxes.
If there’s infill it means the walls are thinner than the part design called for.
I was writing up some additional questions as I didn’t quite get your suggestion, but while writing the response I think I understand. You suggest that I increase wall thickness in the slicer settings to match the model thickness, and not only in the model?
I was hoping to use infill to get some support between the outer walls and avoid having to use too much plastic and not having a single, free-standing wall.
If I understood you correctly, do you have a suggestion to what a suitable wall thickness would be to avoid the issue I described?
Good lord no. Don’t do that. That would be a waste of filament and also cause a host of other problems for you.
Determining how many walls and perimeters you might need for any print, depends on how much you intend to stuff in your bin and what size nozzle you are using.
Usually, I use a .60mm nozzle to print gridfinity parts. That way I can easily use 2 walls for perimeters. But if you don’t have a .60mm nozzle and only a .40mm, that’s fine too. I would just increase the number of perimeters to 3 and get about the same wall thickness. Using too many walls may cause problems with warping due to uneven cooling. Or if it’s a light duty bin, like one meant to hold small screws, 2 perimeters would work as well and be faster and cheaper to print.
For infill choices, adaptive cubic is just fine for the majority of gridfinity bins, since the majority for strength to be had in 3D prints comes from the top, bottom, and perimeters, (and this is why we increase those for get the strength). But if you need the extra strength, something like gyroid works well, (and you’re maxed out at 20% infill).
Good lord no. Don’t do that. That would be a waste of filament and also cause a host of other problems for you.
Just to be clear, it is the “hoping to use infill to get some support” that your response is aimed at, right? Out of curiosity, what kind of problems could I be looking at for this?
In the meantime, I’ve been printing some smaller bins of about half the height of my problem where I increased the wall thickness of the model from the default 0.95 mm to 2 mm, and used 3 perimeters, which resulted in fairly sturdy walls.
Looking at the same bin with 2 mm walls without infill, and 3 mm walls with infill, there is barely any difference in material usage.
Use enough wall loops such that no infill is used.
