Move Aside Planar, I’m Slicing My Cone Way

Fleetwood Mac puns aside, very little has changed about how we “slice” models for printers in the last 30 years. However, [Stefan Hermann] of CNC Kitchen has a demo that tries to change all that by slicing conically.

For the uninitiated in the dark arts of printing in the third dimension, the canonical definition of non-conical slicing has been to bisect the model at layer height intervals and generate the perimeter and the infill, then output that as g-code. This is easy to implement mathematically and works reasonably well, except when you have overhangs of more than about 60 degrees on most printers. The idea of slicing in a cone rather than a plane isn’t entirely novel as we previously covered RotBot, which offers a vertical axis of rotation and a print head at 45 degrees. What is extraordinary is that the technique [Stefan] walks you through is done with a stock printer without a complex 45-degree tilt and is a software modification rather than a hardware tweak.

[Stefan] references earlier work done by [Michael Wüthrich] of ZHAW School of Engineering, who wrote some scripts that apply the transformation. The slicer is SuperSlicer, a fork of the PrusaSlicer, which is itself a fork of slic3r. The modified g-code is exported and can be sent to a printer of your choice. He even has a link to a pre-sliced model to try it out.

Of course, different printers have different clearance levels, but the Prusa Mini he uses has 16 degrees of clearance with the sensor pushed up. The code is on GitHub. It’s fascinating to note how all these techniques and forks interact and build off each other. Whether tilted slices, conical slices, or something else ultimately becomes the de facto standard, we’re looking forward to more options for slicing.

Video after the break.

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3D Printing 90° Overhangs With Non-Planar Slicing

When slicing a model for 3D printing, the part is divided into a stack of flat, 2D layers. But there’s an alternative in the form of non-planar slicing, where the layers can follow 3D curves. [Rene K. Mueller] took this a step further and successfully used non-planar slicing to print 90° overhangs on a normal Cartesian FDM printer.

Non-planar layers have been around for a while, but were generally limited to creating smooth curves without layer lines. The idea of using the technique for overhangs had been floating around in [Rene]’s head for a while, and he was spurred to action after seeing the rotating tilted nozzle printer featured here on Hackaday. The idea is only to have the outer edge of each layer overhang, by making each layer slope downward toward the overhang. [Rene] programmed a conic slicer algorithm for this purpose, which splits the model into dome-shaped layers, like an onion.

He did a lot of testing and documented the results in detail. Conical slices were compared with tilted slices, which are also used for belt 3D printers. Both have some geometric limitations. Tilted slices can only print the overhang in one direction, but conical slices can do this in all directions, allowing it to create a mushroom-like shape without any support. The limitation is that it can only print inward or outward from a central point. More complex geometry must be segmented, and each sub-volume sliced separately. The slicing angle is also limited by the shape of the print head, to avoid it crashing into the print.

We think this technique has a lot of potential for widespread use, especially since it is compatible with most existing FDM printers. It is still a work in progress, but support has already been added for Slic3r and Prusa Slicer. We look forward to seeing how it develops and gets adopted.

Hackaday Prize Entry: Invisible

[Kate Reed] found a quote by a homeless person that said “No one sees us”, which led her to exploring what it actually means to be invisible — and if we actually choose to be invisible by hiding away our emotions, sexual preference, race or income. She realized that too often, we choose to only see what we want to see, rendering all the rest invisible by looking away. Her public art campaign and Hackaday Prize entry “Invisible” aims to increase social awareness and strengthening the community by making hidden thoughts, feelings and needs visible.

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Open Source SLA Printer Software Slices From The Browser

Resin-based SLA printers need a different slicing algorithm from “normal” melted-plastic printers. Following their latest hackathon, [Matt Keeter] and [Martin Galese] from Formlabs have polished off an open source slicer, and this one runs in your browser. It’s Javascript, so you can go test it out on their webpage.

Figuring out whether or not the voxel is inside or outside the model at every layer is harder for SLA printers, which have to take explicit account of the interior “empty” space inside the model. [Matt] and [Martin]’s software calculates this on the fly as the software is slicing. To do this, [Matt] devised a clever algorithm that leverages existing hardware to quickly accumulate the inside-or-out state of voxels during the slicing.

[Matt] is stranger to neither 3D mesh manipulation nor Hackaday. If you’re just getting started in this realm, have a look at Antimony, [Matt’s] otherworldly CAD software with a Python interface to get your feet wet with parametric 3D modeling.