Is this the next revolution in 3D printing
nozzles? Bondtechs CHT nozzles have a totally unique design where your filament gets split
up into three individual strands to significantly improve melting performance. Does this render
volcano hotends obsolete? I’ve taken a closer look at this new design and tested its performance,
print quality, and even cut one up to take a look on the inside. Let’s find out more!
Guten Tag everybody, I’m Stefan, and welcome to CNC Kitchen.
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if you use code CNCKITCHEN at checkout. Regular 3D printing nozzles look all pretty
much the same on the inside. There is one drilled hole that’s slightly bigger than
your filament diameter that goes almost all the way to the tip at which point the small
orifice bore starts that defines your nozzle diameter. There is some slight variation with
the cheapest ones just drilled with a standard 118° drill tip. E3D tried to improve on that
many years ago with a stepped bore probably to improve internal flow but now uses as many
other higher-quality manufacturers a special drill bit with a pointier tip for better flow
characteristics. Ultimaker still uses a special stepped geometry in their AA-print cores maybe
for less oozing during retracts. Though these are all just slight variations of a simple
design. This right here is Bondtechs new CHT nozzle
that features a special core that splits up your filament into three separate channels.
CHT means Core Heating Technology which means that the material is not only melted from
the outside in, but also from the inside out promising higher melt rates. Bondtech is actually
not the one who came up with this idea. Maybe you have already seen the Matchless nozzles
from 3DSolex that have been around for a while, though never been particularly popular. Bondtech
has now licensed the core heating technology and made their own version of it. They licensed
it because it’s unfortunately patented by 3DSolex but I’ll get to that later.
The CHT nozzles are a drop-in replacement for your standard E3D and RepRap nozzles with
an M6 thread though you can even use them on an Ender-3 and its derivatives. It’s
a high-flow nozzle and therefore currently only comes in sizes starting from 0.6mm up
to 1.8mm, though I would like to see a 0.4mm variant as well. The Bondtech CHT is made
from brass with a nickel coating that protects against corrosion and makes the surface less
sticky to plastic but is not as wear-resistant as hardened steel for example and is therefore
not suitable for your carbon fiber materials. I was happy to see that it’s at least, in
my opinion, very reasonably priced at 20 bucks so won’t break the bank. Before we cut one
open and try to figure out how looks on the inside and gets manufactured let’s see how
it performs and benchmark it against a standard V6 nozzle and I think ways more interestingly
an E3D Volcano! For our first performance test, I’ve compared
the 0.6 mm variants. To make the tests as comparable as possible, I’ve done them all
on the same E3D Hemera using the same heater cartridge, thermistor, and for both standard
V6 as well as the Volcano used silicone socks for insulation.
The extrusion test is really simple and I basically just tell the extruder to feed 200
mm of filament and weigh the extruded spiral of material. I then gradually increase the
extrusion speed. At some point, the hotend won’t be able to properly melt the material
anymore which results in more back-pressure and more and more slip in the extruder gears.
At that point less material gets extruded, which I can measure with my scale. Just to
give you an idea of what normal and high melt rates are take a look at these examples. With
normal prints using a standard 0.4 mm nozzle at 0.15 mm layers we’re mostly printing
at around 5 mm³/s or less. Using a 0.6 mm nozzle with thicker 0.35 mm layer we max out
at around 15 mm³/s because this is often the limit of normal extrusion systems so profiles
are tuned for that. If you want to effectively use even bigger nozzles or go faster, high
flow extrusion systems are necessary. So let’s get to the test. I first benchmarked
the reference, a 0.6 mm V6 nozzle. As just said, with this standard setup we can usually
go up to 15 mm³/s extrusion rate which I again confirmed by this test. At that point,
we already under extrude by 5%, anything more and the extruder will start severely stripping
and skipping. At 20 mm³/s the results are unusable anymore with 25% of under extrusion.
Let’s compare that to the standard high-flow setup from E3D, the volcano, which significantly
increases the length of the meltzone. Using this setup we can basically double the extrusion
rate and under extrude around 5% at 30 mm³/s after which point things get really bad and
unusable. Let’s now change back to a standard length heater block and install the Bondtech
CHT nozzle. 15 and even 20 mm³/s didn’t seem to be a problem and we still get perfect
flow. At 30 mm³/s, which was the limit for the volcano setup, we can see the curve is
slightly getting worse but we’re still only under extruding by 2%. At 40 mm³/s we’re
just reaching the 5% under extrusion limit and are this way 33% better than the Volcano
and almost 200% better than our standard V6 nozzle which is unbelievable. If we go even
higher we can clearly see that we reached the limit of the CHT, but man, better performance
than a volcano hotend at the size of a V6 nozzle. The thing that was interesting to
observe was the change of melt behavior. I also did the same test with a 1 mm nozzle
which restricts the flow less and allows the volcano to be usable up to 45 mm³/s though
the CHT 1 mm performed like a champ up to 60 mm³/s and only started skipping at 90
mm³/s which is probably more than you will ever need!
Okay, so where do we continue now? Well, to better understand how the nozzle is manufactured
and how it looks on the inside, I, of course had to sacrifice a brand new one and cut it
open on my CNC router. This nicely shows the yellowish brass base material with the nickel
coating on the outside and we can get an idea of how they probably manufacture the unique
geometry. Instead of one straight bore they drill 3 times at an angle which all terminate
at the same point. The sharp edge of the divider, I think, was done when they pilot-drilled
with a bigger bit. I assume they first pilot drill with a bigger bit to create the sharp
edge and then use a 1.2 mm bits for the material channels. Really clever design and I bet tricky
to manufacture at this size if you’re not careful. The thing that surprised me at first
but gets clearer if we take a look at my reverse engineered CAD model, is that the core, for
which the C in CHT stands is way smaller than one might expect and looks more like a blade
that splits the filament rather than significantly contributing to the heating of the material.
As cruel as might be to some, but I actually drilled out the divider on one nozzle and
tested it. The results showed that it still performed way better than a standard nozzle
but has a significantly worse performance at higher melt rates compared to the unmodified
one and even slightly falls short of the volcano. So the filament splitter significantly contributes
to the performance but the other maybe even more important and smart design of the CHT
is the increase of the heating surface by the cloverleaf shape that the 3 bores generate.
A single circle is just the physically worst choice for heating something because it has
the smallest circumference compared to the area. Any deviation from that is better, though
a circular hole is obviously the easiest to manufacture. Secondly, since plastics are
such a bad conductor of heat the distance from where you heat to the center of the material
is also crucial, which is smaller with the cloverleaf shape compared to a circle. Having
the heating core in at least part of the nozzle makes that even better and due to the sharp
edges, it also shouldn’t constrain the flow too much. And then there is the overall conical
shape of the material channel which I can’t fully judge but might also lower flow resistance
and gradually decrease the distance from the hot walls to the center of the material. Overall
a top-notch design, which also shows in the more than impressive melting performance.
But how does the design with the melt splitter and the undercut at the heatbreak do in a
realistic printing scenario where you have retractions and travel moves?
The retraction and stringing test printed with the 0.6mm nozzle looked very comparable
and even with this high amount of retracts there didn’t seem to be any clogging due
to the CHT shape. Bigger nozzles have the tendency to string more and the amount I’m
seeing seems reasonable. My own Mini-Me and a 200% scaled-up Marvin looked almost indistinguishable
with even a bit better overhangs using the Bondtech nozzle. The other prints that I did
with the 0.6 and 1.4 mm CHT nozzle turned out really well. My 200% Mini-Mi took an hour
to print with extrusion rates up to 40 mm³/s. The print looks great just the amount of cooling
that the Prusa provides is the bottleneck at some point and the layer doesn’t properly
solidify before the next one is printed on top. I first had failures at higher extrusion
rates on the 300% Benchy due to thermal runaway but adding a silicone sock fixed that. Just
by doing the maths, the 40W of the heater is plenty to melt that amount of material.
There were some areas with a bit of underextrusion at 40mm³/s but I’m certain that 30 or even
35mm³/s would have worked well with Prusas extrusion system. Cold pulling a CHT nozzle
for cleaning purposes is possible, yet I only managed to do it once, though I carefully
burnt out one nozzle successfully, but don’t recommend it because I’m not sure if that
might chip the nickel coating. So will this become the new standard of how
every 3D printer nozzle will look? I’m quite sure no. For once, there is additional effort
and precision necessary during manufacturing and not everyone will need the additional
performance. The more striking argument though is the patent behind this technology that
Bondtech in this case licensed from 3DSolex. I linked the patent below if you’re interested
which was granted in 2019. It covers various techniques that can be used to improve the
melting rate of a nozzle by increasing surface area and heating the material from the center.
I’m not a patent expert and I don’t know if there might even have been prior art on
the RepRap forums. On the one hand, I think it’s a legitimate invention that ended up
in an improved product so deserves some kind of protection and credit. On the other hand,
I find it kind of sad, that this now blocks other companies for the next 20 years of implementing
something similar in for example a wear-resistant high flow nozzle. Still, the inventor seems
to at least be kind of open to licensing the technology. Another way is trying to work
around patents that often sparks creativity in engineers. So maybe even you have an idea
to improve on it! In summary, I can only say that I’m hugely
impressed by the performance of Bondtechs CHT nozzle, and the 30% increase in flow rate
that they advertise is seriously the minimum I think you can expect. Even though they sent
me the nozzles free of charge, I didn’t get paid, or were they able to review the
video. The numbers and the print results objectively show that these nozzles are a serious improvement
to what we all used in the past and renders, in my opinion, at least for the moment, many
high flow hotends obsolete because you can get similar performance by just switching
out a nozzle. Additionally, the decrease in length and lower mass are very interesting
for high-speed printing. That said, not everyone currently has a need for this style of nozzle
especially since they are currently only available starting from 0.6 mm upward. Bondtech, I hope
you are listening but I reeeealy want a 0.4 mm variant for fast and detailed printing
and I’m sure I’m not the only one! Since extrusion performance is also depending on
your feeder, don’t expect the same results when changing the nozzle in a standard Ender-3.
Still, for anyone, who’s looking for a simple solution to easily print faster and especially
with bigger nozzles, these 20 bucks will be so well spent! Let me know down in the comments
what you think about these new nozzles and if you ever used one, what your experience
was. Thanks to Squarespace for sponsoring part
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Also thank you for watching! I hope you found this review interesting! If you want to support
my work, consider becoming a Patron or YouTube member and check out the other videos in my
library! I hope to see you in the next one! Auf wiedersehen and goodbye!
