Start using your slicer a bit more creatively! You’ll find you can efficiently print parts that would be impossible to model if you make 3D printing’s quirks work in your favor.
Slicers do a lot of the heavy lifting in 3D printing – they always have, but now that we’re getting closer and closer to the limits of what we can squeeze out of the mechanical hardware that we have, the optimizations in the slicer are one of the few things that can not only make the same prints complete faster and with fewer artifacts, but they make some things possible in the first place, like support material that just peels off. That works on almost any printer now, and all it took was figuring out how to create the G-code for it.
But what if we start doing things that weren’t intended that way? Well, it turns out that even without going for deeply involved tools like full control G-code, just giving your slicer the right nudges allows you to print parts that would be really hard to print or even model in the first play. So in this video, I’m going to show you the tricks I had to use for making this refillable Ikea activated carbon cartridge and this printer enclosure fan and filter mount. There is a lot of complex geometry in this, but with these tricks, it all prints super easily.
Before we start, I’m showing all this in PrusaSlicer, but it’s going to be the same functionality in something like OrcaSlicer as well, and as of end of January 2025, which is when I’m filming this, should also still be accessible for free for Bambu users.
Open-air Lattices
Starting with the first one, creating open-air lattices. If you’ve ever tried to add a bunch of holes in CAD for airflow, for cooling, or for allowing air through this activated carbon material, you will probably have run into some limitations. With something like the sensorbox, where there’s only a limited number of well-defined holes, most CAD tools will have something like fill patterns that allow you to perforate a defined area of your part with a pattern of your liking. This sensorbox was modeled with real geometry and then cut out with booleans because I needed some more control over it, but both options only work up to, let’s say a couple of hundred holes before your software starts chugging.
Plus, it creates a ton of geometry that is hard to work with, and not optimized for printing at all. So what I did here instead, is to simply model some overlapping geometry of where I wanted to turn the part into an open-air lattice. Because all you have to do in the slicer is to import that overlapping geometry as a modifier mesh and you then apply any slicer settings for just the area of the overlap.
Typically, you’d use this to, like, increase infill and wall thickness to reinforce your parts, but in this case, I’m turning down perimeters and top and bottom solid layers to zero, switching the infill pattern to Triangles and then with the infill percentage, I can adjust how tight of a lattice I want. I thought about gluing bits of insect screen material, but this is so much easier and faster. I’m also thinking about using this for a speaker grill.
I like the results best when you print the part flat because that’s when the infill prints the cleanest, but in a pinch, you can also use this for vertical walls. Triangle infill won’t work here, but for example Gyroid is a pattern that is never air-tight in any direction. What I’ve also used is Rectilinear, because here, the quirk of Rectilinear leaving one-layer gaps between each pass actually works in our favor and creates a microscopic mesh. I did find that I had to slightly turn down the extrusion width for infill for this to work, and for any vertical passages you print like this, you’ll also have to experiment with the infill anchor settings, you may not want to turn them off completely, but the preview is pretty helpful for seeing how things might turn out.
Adjustment and Trial Pieces
The second one, tying in here, is for printing adjustment and trial pieces. You might not always want to print the full piece if you’re just trying out a print setting, so what you can do in the slicer is adding a couple negative volumes and just blocking out all the areas of your part that you don’t need for now. You can adjust the rest of your slicer settings as usual, print off your little test pieces, and once you’ve found the settings that will work for you, you can simply get rid of the negative volumes and print off the entire thing perfectly on the first try.
Bridges
Bridges can absolutely work in your favor and make the unprintable printable. The example that you might have seen already is upside-down counterbore screw holes, where instead of just having a single layer with a hole in the middle, that inevitably ends up printing not very well, you add two shoulders that can get printed as a clean bridge first and then allow the full hole geometry to be printed on top of that.
I’m using a similar concept with this fan shroud. On the inside, it has got these air guide fins that, eventually, will also end up supporting a lot of geometry on top of it. But there were two things that I had to implement to make this work. First, I had to extend the geometry so that it would get anchored to one of the actual air guides instead of ending in thin air, and I also offset every other segment one layer up so that they wouldn’t be printed as one big bridge, but instead, be split into segments and give the slicer an opportunity to optimize the bridging direction for each one separately.
This sort of bridging logic can be applied in so many different ways, and it’s surprising what you can get away with if you use it right. But I’m still rooting for arc overhangs to be widely available.
By the way, an alternative way of solving this hollow part challenge would be by using a modifier mesh, and instead of manually creating these air guides, you’d use the modifier to turn off perimeters and solid top and bottom layers, and fill the space with low-density Gyroid or with the Lightning infill, which only prints where needed to support overhangs.
This, of course, might end up a little more restrictive on airflow, but it’s a lot easier to model and print.
And lastly, you can actually do some modeling in the slicer, even though it’s not always super comfortable. You may have seen the option to add text to your parts, which I find super useful if you just want to quickly label your parts with when you’ve printed them or what the exact filament is, but you can also do some Tinkercad-level modeling right inside your slicer. I already showed you the negative volumes, but you can also just add basic positive primitives that add on to your part. So let’s say I’ve got a part that I need an extra pair of screw holes on, I can add two cylinders, position them, and then import the geometry of the self-forming threads from my last video as a negative volume, and … last-minute change complete.
You can, of course, save this whole project as a 3mf, and if you then make other changes to the original stl, but still need the added screw holes, you can open up your slicer project again, click “reload from disk”, and all your changes and settings are now applied to the updated stl.
I hope this was helpful, thanks for watching, and keep on making. Bye!
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