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 fullcontrol.xyz, 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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RotBot Adds An Extra Dimension To 3D Printing, With A Twist

It always seemed to us that the Z-axis on a 3D printer, or pretty much any CNC machine for that matter, is criminally underused. To have the X- and Y-axes working together to make smooth planar motions while the Z-axis just sits there waiting for its big moment, which ends up just moving the print head and the bed another fraction of a millimeter from each other just doesn’t seem fair. Can’t the Z-axis have a little more fun?

Of course it can, and while non-planar 3D printing is nothing new, [Stefan] over at CNC Kitchen shows us a literal twist on the concept with this four-axis non-planar printer. For obvious reasons, it’s called the “RotBot,” and it comes via the Zurich University of Applied Sciences, where [Michael Wüthrich] and colleagues have been experimenting with different slicing strategies to make overhang printing more manageable. The hardware side of things is actually pretty intuitive, especially if you’ve ever seen an industrial waterjet cutter in action. They modified a Prusa printer by adding a rotating extension to the print head, putting the nozzle at a 45° angle to the print bed. A slip ring connects the heater and fan and allows the head to rotate 360°, with the extruder living above the swiveling head.

On the software side, the Zurich team came up with some clever workarounds to make conical slicing work using off-the-shelf slicers. As [Stefan] explains, the team used a “pre-deformation” step to warp the model and trick the slicer into generating the conical G-code. The G-code is then back-transformed in exactly the opposite process as pre-deformation before being fed to the printer. The transformation steps are done with a bit of Python code, and the results are pretty neat. Watching the four axes all work together simultaneously is quite satisfying, as are the huge overhangs with no visible means of support.

The academic paper on this is probably worth a read, and thankfully, the code for everything is all open-sourced. We’re interested to see if this catches on with the community.

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Go Big Or Go Home: 0.6 Mm Nozzles Are The Future

Most desktop fused deposition modeling (FDM) 3D printers these days use a 0.4 mm nozzle. While many people have tried smaller nozzles to get finer detail and much larger nozzles to get faster printing speed, most people stick with the stock value as a good trade-off between the two. That’s the conventional wisdom, anyway. However, [Thomas Sanladerer] asserts that with modern slicers, the 0.4 mm nozzle isn’t the best choice and recommends you move up to 0.6 mm.

If you know [Thomas], you know he wouldn’t make a claim like that without doing his homework. He backs it up with testing, and you can see his thoughts on the subject and the test results in the video below. The entire thing hinges on the Ultimaker-developed Arachne perimeter generator that’s currently available in the alpha version of PrusaSlicer.

We’ve experimented with nozzles as small as 0.1 mm and, honestly, it still looks like an FDM 3D print and printing takes forever at that size. But these days, if we really care about the detail we are probably going to print with resin, anyway.

There are a few slicer settings to consider and you can see the whole setup in the video. The part where an SLA test part is printed with both nozzles is particularly telling. This is something that probably shouldn’t print well with an FDM at all. Both nozzles had problems but in different areas.

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SuperSlicer Reviewed: Another 3DP Slicer?

When you think of slicers for FDM 3D printing — especially free slicers — you probably think of Cura, Slic3r, or PrusaSlicer. There are fans of MatterControl and many people pay for Simplify3D. However, there are quite a few other slicers out there including the one [TeachingTech] has switched to: SuperSlicer. You can see his video review, below.

Of course, just as PrusaSlicer is a fork of Slic3r, SuperSlicer is a fork of the Prusa software. According to the project’s home page, the slicer does everything Prusa does but adds custom calibration tests, ironing, better thin wall support, and several other features related to infill and top surfaces. The software runs on Windows, Linux, or Mac.

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Open Source CAM Software In The Browser

3D printers, desktop CNC mills/routers, and laser cutters have made a massive difference in the level of projects the average hacker can tackle. Of course, these machines would never have seen this level of adoption if you had to manually write G-code, so CAM software had a big part to play. Recently we found out about an open-source browser-based CAM pack created by [Stewert Allen] named Kiri:Moto, which can generate G-code for all your desktop CNC platforms.

To get it out of the way, Kiri:Moto does not run in the cloud. Everything happens client-side, in your browser. There are performance trade-offs with this approach, but it does have the inherent advantages of being cross-platform and not requiring any installation. You can click the link above and start generating tool paths within seconds, which is great for trying it out. In the machine setup section you can choose CNC mill, laser cutter, FDM printer, or SLA printer. The features for CNC should be perfect for 90% of your desktop CNC needs. The interface is intuitive, even if you don’t have any previous CAM experience. See the video after the break for a complete breakdown of the features, complete with timestamp for the different sections.

All the required features for laser cutting are present, and it supports a drag knife. If you want to build an assembly from layers of laser-cut parts, Kiri:Moto can automatically slice the 3D model and nest the 2D parts on the platform. The slicer for 3D printing is functional, but probably won’t be replacing our regular slicer soon. It places heavy emphasis on manually adding supports, and belt printers like the Ender CR30 are already supported.

Kiri:Moto is being actively improved, and it looks as though [Stewart] is very responsive to community inputs. The complete source code is available on GitHub, and you can run an instance on your local machine if you prefer to do so. Continue reading “Open Source CAM Software In The Browser”

Rarely Adjusted Slicer Setting Makes A Difference

When you 3D print something, you probably adjust the layer height based on your desired print quality. Speed is another parameter that many people adjust. But what about extrusion width? The parameter is there, but most people leave it at the defaults. [Stephan] wondered about it, and after running some tests, made a video you can see below trying to determine if it affected strength and print quality.

The tests were pretty straightforward. Some Benchys and other test pieces at each setting were observed and — in some cases — destroyed. He ranged the width from 90% to 250% of a 0.4mm nozzle. Important to note, his results are from a nozzle that has a flat lip around the aperture. If yours doesn’t look like that, you will see different results.

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There’s More To The 3D Print Than The Eye Can See

If you thought CADing designs for 3D printing was hard enough, wait until you hear about this .stl trick.

[Angus] of Maker’s Muse recently demoed a method for creating hidden geometries in .stl files that are only revealed during the slicing process before a 3D print. (Video, embedded below.) The process involves creating geometries with a thickness smaller than the size of the 3D printer’s nozzle that still appear to be solid in a .stl editor, but will not be rendered by a FDM slicer.

Most 3D printers have 0.4 mm thickness nozzle, so creating geometries with a wall thinner than this value will result in the effect that you’re looking for. Some possible uses for this trick are to create easter eggs or even to mess with other 3D printing enthusiasts. Of course, [Angus] recommends not to use this “deception for criminal or malicious intent” and I’d have to agree.

There’s a few other tricks that he reveals as well, including a way to create a body that’s actually a thin shell but appears to be solid: great for making unprintable letters that reveal hidden messages.

Nevertheless, it’s a cool trick and maybe one of those “features not bugs” in the slicer software.

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