Arc Overhangs Make “Impossible” 3D Prints

An accidental discovery by [3DQue] allows overhangs on FDM printers that seem impossible at first glance. The key is to build the overhang area with concentric arcs. It also helps to print at a cool temperature with plenty of fan and a slow print speed. In addition to the video from [3DQue], there’s also a video from [CNC Kitchen] below that covers the technique.

If you want a quick overview, you might want to start with the [CNC Kitchen] video first. The basic idea is that you build surfaces “in the air” by making small arcs that overlap and get further and further away from the main body of the part. Because the arcs overlap, they support the next arc. The results are spectacular. There’s a third video below that shows some recent updates to the tool.

We’ve seen a similar technique handcrafted with, but this is a Python script that semi-automatically generates the necessary arcs that overlap. We admit the surface looks a little odd but depending on why you need to print overhangs, this might be just the ticket. There can also be a bit of warping if features are on top of the overhang.

You don’t need any special hardware other than good cooling. Like [CNC Kitchen], we hope this gets picked up by mainstream slicers. It probably will never be a default setting, but it would be a nice option for parts that can benefit from the technique. Since the code is on GitHub, maybe people familiar with the mainstream slicers will jump in and help make the algorithm more widely available and automatic.

What will you build with this tool? If you don’t like arcs, check out conical slicing or non-planar slicing instead.

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3D Print In The Air With A Little Software Support

We all love 3D printing, but printing anything that has an overhang requires support, right? Maybe not. [Create Inc] has a video showing some 3D prints that seem to hang impossibly in the air — not bridges, but loops just floating in the air. You can see the effect in the video below.

The first part of the post covers gcode basics. Around the 5:30 mark, [Create] talks about his inspiration: FullControl Gcode Designer. You can do a lot with this tool and it inspired [Create’s] similar web-based version.

The point of these tools is to make it easier to create gcode directly instead of using a slicer. You can think of it as assembly language for 3D printing — you can do almost everything in the high-level language — 3D models — but if you want ultimate control you use assembly language, or, in this case, gcode.

The original tool uses Excel which didn’t visualize the output directly and could not provide proper error checking. The new tool solves those problems and is much easier to use.

If you know gcode, you can do a lot of interesting things. You can even put a spring in your step.

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Supportless Overhangs: Just Reorient Gravity By 90 Degrees

The 3D print by [critsrandom] in the image above may not look like much at first glance, until one realizes that the 90 degree overhang has no supports whatsoever. Never mind the messy bottom surface, and never mind that the part shown might avoid the problem entirely with some simple supports or a different print orientation; the fact that it printed at all is incredible.

[critsrandom] shared the method in a post on Reddit, and it consists simply of laying the 3D printer on its side. When the print head reaches the overhang, the fact that it is printing sideways is what allows that spot to make the leap from “impossible” to merely “messy”. Necessary? Probably not, but a neat trick nevertheless.

Tilted 3D printers is something that we’ve seen in the past, but for different reasons. When combined with a belt-driven build platform, a tilted printer has a theoretically infinite build volume (in one axis, anyway.)