These are some impressions of what could be
possible with the next generation of 3D printing slicers. Completely overhanging surfaces without the
need for any supports printed on a standard machine! I’ll tell you why current slicer are dump,
how you can try out the next generation of slicing and even how you can contribute that
they become a reality soon. Let’s find out more. Guten Tag everybody, I’m Stefan and welcome
to CNC Kitchen. This video is sponsored by Squarespace. Easily create the website you’ve always
wanted or replace your old one you’ve always hated. Save 10% by visiting squarespace.com/cnckitchen. Current 3D printing slicers are dumb. What I mean by this is that even though they
are slicers for 3D printing they simply stack 2-dimensional layers on top of each other
to form your final part. There are basically no movements within the
GCode instructions where all 3 axes move simultaneously. That’s why current 3D printing slicers are
rather 2.5D slicers. But why are they using this approach? Well, simply because it’s mathematically
easy and honestly because this approach works remarkably well. Yet we are leaving a ton of potential on the
table because 3D printers are easily capable of complex 3 dimensional moves, yet we don’t
have any software to take advantage of it. Over the last few years 3D printer slicers
didn’t really change a lot besides being way easier to use and much quicker. Yet the general slicing approach always stayed
the same. Cut a 3D part into a 2-dimensional slice,
draw perimeters around the circumference and fill the rest with one of many infill patterns. The only real evolution we’ve seen this
year is the Arachne Perimeter generator first seen in CURA that dynamically adjusts the
width of the extrusions for more details and fewer gaps. Still, everything is on a two-dimensional
plane, which causes the typical stairstepping pattern on sloped surfaces and of course,
requires supports on overhanging structures. Over the years we have seen a couple of approaches
of non-planar slicing, often to improve top surfaces, yet none of them ever really made
it into a mainstream slicer. Though quite recently we have seen a couple
of really impressive ways of 3D printing parts that have previously been deemed impossible
by using really clever slicing approaches. One of them is non-planar, conical slicing. A bunch of weeks ago I’ve shown this technique
in my RotBot video, where I visited the University of Applied Science in Winterthur, Switzerland,
where they built a 4-axis Prusa printer that can manufacture complete overhangs without
the need for support structure. Yet the best thing is, that we can use the
same slicing approach on regular 3-axis printers to achieve very similar results. And this isn’t just an idea published in
a paper, but you can download the Python scripts necessary and try this out on your own parts
and prints. I also uploaded a bunch of sample G-Codes
on Printables for the not-so-programming-savvy! If you print them or even slice your own,
please share the results and spread awareness around this method and maybe consider subscribing
to the channel for more like this in the future! So let’s quickly talk about the idea behind
this approach. Common FDM 3D printers are able to print quite
steep angles, yet at some point, particularly below 10 or 15 degrees, the plastic will just
be extruded into free air, drooping down and ruining your print quality. This novel slicing approach tilts the layers
a tiny bit so that even when printing horizontal overhangs, only maybe the outermost perimeter
is printed in mid-air, yet still sticks and is supported by the perimeter next to it. This way you can print even these extreme
geometries without the need for supports. The conical slicing approach, which stems
from the RotBot project, even improves this concept and tilts the printing layers around
a central axis and therefore forms a cone. Since we’ll be printing our parts on a regular
printer instead of one with a tilted printhead there is one essential thing that needs to
be taken care of, and one of them is nozzle clearance. Conventional 2.5D printing only needs to make
sure that the nozzle is the lowest part of the printhead, because we're only printing
on a plane and nothing besides warped plastic should stick up. When we’re printing with non-planar GCode
there are sections of the print that will be on a higher level than the current print
move. This is why before we start the first non-planar
code we need to figure out, what the maximum slope angle of our print can be. Unfortunately many current printers only allow
tiny slope angles because of their cooling systems that reach down almost to the print
plate. The only printer I had that worked acceptably
out of the box was my Prusa Mini, which has quite a high part cooling shroud and if you
print small parts allows up to around 20° slicing angle. Bigger parts will still crash into the bed
leveling probe, and I often just pushed it up after the leveling process. For other machines like all the Ender-3 derivatives,
a really simple solution is just using a longer nozzle, like one of these airbrush nozzles
to which I put a link down in the description, or simply a regular volcano nozzle. That looks a bit wired but works better than
one might expect. Just remember to move your endstop! Unfortunately, cooling is not the best this
way even though it’s quite essential for printing these extreme overhangs. The airbrush nozzle is a bit better here because
it’s only a little longer than a standard nozzle and therefore still closer to the initial
cooling location. So if you want to try this out make sure you
have enough clearance and optimize cooling as much as you can! But which slicer can you use to create this
tilted GCode? This is the cool thing about this method because
you can basically use your own, favorite slicer for this. The thing is that there is no simple check
box for conical slicing at the moment and you need to trick your slicer into generating
conical GCode with a clever trick! We simply use two Python scripts for this,
and I’ll go over how you can easily do this yourself in a second. The first code is pre-deforming the stl in
a reverse cone shape, by simply moving the points of the mesh upwards, depending on their
distance to the center axis. Then you slice this slightly wired-looking
part in CURA, PrusaSlicer, Simplify3D or almost any other tool and use a second script to
back-transform the movement commands within the GCode file to end up with the conical
Gcode that’s ready to print. It’s really simple! If you want to try this out yourself all of
this is Open Source, and was developed by the ZHAW in Switzerland. During making this video and working with
their code I created a fork of their project to make it in its current state easier usable,
fix some bugs and add some features. Nothing really crazy but in my opinion, it
works better. I linked everything in the description! The code that we’ll be using is in the “Scripts
for Variable Angle” folder. So here’s the process and I’m using SuperSlicer
for this demo because it has some additional features over PrusaSlicer and most importantly
has a switch that lets you export GCode with empty layers, which is sometimes really handy
for this method! I load my stl file into the slicer with a
slightly adjusted printer profile where the bed origin is in the center. I move my part so that the global z-axis represents
the axis of the cone that I want to use for slicing and save the part in this new location. In the transformation script, I set my slicing
angle and run it which spits out the pre-deformed stl, that’s ready to be loaded back into
the slicer. Now I make sure that the cone axis of the
slt is again at the origin of the coordinate system and then simply slice my part and save
the GCode. Then I paste the name of this GCode into the
second script, make sure that the right cone angle is set, and hit run to start the back
deformation. And that’s it! Ready to run conical GCode generated in a
minute! I also wrote a comprehensive guide on my website
through which you should go step by step to ensure that you get out nice GCode because
some essential things need to be taken care of! One of the huge pain points of PrusaSlicer
and CURA is, that they don’t position parts in their local STL coordinate system but choose
one by themselves. There is a switch in PrusaSlicer that should
get around this, but it seems to have been broken for a while, so please guys, fix that
because currently, I need to use a ton of trickery to position non-symmetric parts properly. The approach is not perfect, still buggy,
and requires a bit of manual work but demonstrates how this novel slicing technique could be
implemented in a regular slicer. Yet, conical slicing won’t fix all of our
overhang and support problems at the moment. If you have watched carefully, you will have
noticed that most geometries I’ve shown so far only had outward-facing overhangs. Any inward-facing overhangs actually would
need even more supports as with the regular 2.5D slicing approach. The current script also allows slicing parts
with an inward cone, yet if your part has both outward and inward-facing overhangs you
will need to slice the sections separately and stack the GCode manually. If you have both inward and outward-facing
overhangs on the same height, you won’t be able to find a solution at all! And this is one of the main limitations of
conical slicing in its current state. It works great for special geometries, but
will probably not be as impressive for any arbitrary geometry. What we’ll need in the future are algorithms
that automatically section the parts, depending on their geometry, and set individual slicing
angles and orientations. An implementation I could imagine for the
future is identifying geometries by their overhang angle or slope angle and calculating
an ideal slicing angle for supportless overhangs and smooth top surfaces. In-between you can interpolate. This field could then be used to pre-deform
the stl and also used for back-transformation giving us non-planar G-Code even with variable
layer height. I’m not the first to come up with such an
idea, and you can find plenty of papers on approaches and algorithms. Unfortunately, I don’t have the time and
probably the skill to do this myself, but I want to spread awareness of how much potential
there still is in slicing software for FDM printing. So if you’re a skilled enthusiast with too
much spare time or a student looking for a thesis maybe consider if a proper non-planar
slicing integration is the challenge you were always looking for. Anything that we as a community can release
and contribute open-source is something no one else can patent. Yet if you are a software company, also think
about if you’d like to be the first to do proper non-planar slicing with your tools. I was happy 6 years ago to pay for Simplify3D
because it did the best supports at that time and I’d honestly be happy to pay a reasonable
amount for a next-generation FDM slicer! Yet new slicing methods, especially non-planar
will also require adjustments in the hardware of our printers. This is why I think, that we won’t see this
being implement in PrusaSlicer and CURA soon, because their machines, especially their printheads
are not yet optimized for that method. Something you have already seen plenty of
in this video is the clearance around the nozzle so that non-planar moves are even possible
without crashing into the print. Also, how should the tip of the nozzle itself
even look like, because the bigger the flat, the more it will interfere with the extruded
plastic. Yet the smaller it is the less ironing action
we will have and material will squish out to the sides. And then there is the z-axis. When this axis is involved in every print
movement it will need to move way more than in a regular print and probably wear out quicker
with the common leadscrew approach. And of course, cooling also plays a major
role if we want to print supportless and need to cool down the plastic as fast as possible. So there is still a ton of really interesting
research and development necessary until we see non-planar slicing in all of our prints,
but I think we have finally reached a point where proper implementations are really close! I’d love to hear your thoughts on the conical
method and non-planar slicing in general. Do you think the current 2.5D slicing approach
is just good enough or do you also see this huge potential in new algorithms? Please let me know in the comments below! And I highly encourage anyone interested in
this method to check my detailed website article that goes over the steps so you can get this
method working on your setup and potentially contribute to it in the future! It’s sometimes just impossible for me to
squeeze all the detailed information in a video and still keep it entertaining and this
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to Patreon or become a YouTube member. Also, check out the other videos in my library. I hope to see you in the next one. Auf wiedersehen and good bye!
