This is ColorFabbs VariShore TPU, a material
that varies its softness by printing it at different temperatures because it foams up.
I tested its properties with a pair of Durometers, and we'll also take a look at the hardenss
of other 3D printing materials and even how you can vary the softness of your parts without
this special filament. Let's find out more! Guten Tag everybody, I'm Stefan an welcome
to CNC Kitchen! A part of this video is sponsored by Audible.
Support the channel and start listening with Audible's holiday offer by visiting Audible
dot com slash cncnkitchen. Previously, we've already been taking a look
at another of Colorfabbs foaming filaments, and that was Light Weight PLA. By printing
that material at temperatures of up to 250°C, you can lower its density by almost 60%, giving
it a really nice texture and, more importantly, making it well suitable for things like RC
airplanes, as, for example, Eclipson perfectly demonstrates.
Colorfabb uses a similar approach and adds a foaming agent, which is in the most simple
case baking soda, to TPU. This foaming agent that is finely distributed all over the material
is activated at elevated temperatures and releases a gas, for example, CO2, and makes
the material foam up in it's molten state. The higher the temperature, the more gas is
released; hence you can use the temperature to adjust the material's density. With Light
Weight PLA this is used to make the material itself lighter while still preserving some
mechanical properties. VarioShore TPU specifically uses the degeneration of mechanical properties
when you lower the density. This results in very soft parts on printers that would otherwise
not be able to handle flexible filaments, or even printing flexibles faster, because
you generate more material volume in the nozzle, and therefore, the extruder doesn't need to
work as hard. Colorfabb sells Varioshore TPU on 700g spools,
which usually cost around 50 bucks. Currently, the material only comes in natural and black.
It doesn't look significantly different than any other TPUs with maybe the minor difference
of a slightly rough and matte surface. This appearance is probably from the foaming agent
or due to the lower temperatures they use during filament extrusion to not activate
the additive while making the filament. I have the feeling that the slightly textured
surface makes it less sticky and I didn't even have issues printing it on an Ender-3,
for example. Usually, I'd definitely recommend a direct drive extruder for most flexibles,
but the Varioshore TPU seems to be usable on Bowden style printers as well, of course,
at low speeds. First, I had to tune the material, and in
this case, I had to find the correlation between extrusion temperature and the flow I needed.
To investigate that, I printed simple single wall parts. In the first iteration, the material
flow for all temperatures was set to 100% in the slicer, which of course lead to thicker
walls at temperatures where we have foaming than the set 0.44mm in the slicer. With those
measurements, I started a second tuning iteration in which I already lowered the flow for each
temperature according to the last wall thickness with the goal to get all walls to the same
dimension. Since the expansion coefficient depends not only on temperature but also on
the extrusion rate, the second values were still not spot-on. I again calculated new
flow values with which I ran a 3rd test interation after which the walls of each temperature
were pretty close to 0.44mm. The final extrusion multipliers were 113% for 190°C where no
foaming occurs, and 57% for 220°C, where we have the maximum expansion.
Interestingly, at even higher temperatures, the expansion seems to be smaller. I don't
have a definitive answer for that, but I assume that at elevated temperatures, the bubbles
in the material get too big and partly collapse. Still, at the ideal temperature, this results
in an expansion of 100%, so half the weight or double the volume as the base material,
which is significant! Printing quality for normal models is mostly
okay, but due to the foaming nature, stringing or material oozing during travel moves is
inevitable, which can be a pain to clean up. Bridges also don't look great with my un-tuned
profile. Everything else looks really great, though—smooth and matte surfaces with no
layer lines and good overhangs. So if you design your part with this filament in mind
and keep travel moves to a minimum, you might be able to produce some really nice looking
parts! We've seen that we can foam up the material
to twice the volume but does this also mean that the material becomes twice as soft? To
test the Shore Hardness variability of Varioshore TPU I reached out to my friends at Mitutoyo
and asked them if I could borrow two of their hardness testers, to which they kindly agreed.
With such a durometer, you measure the indentation depth in a material created by a standardized
indenter at a given force. The hardness of a material is then measured in Shore hardness
on a given scale that corresponds to a specific indenter and force. 100 Shore means no penetration
of the indenter, 0 Shore means that the whole range of the tip indented the material. The
most common harness scales we're usually confronted with in Shore Hardness A and D. D is for plastics
and harder rubbers and features quite a sharp tip, whereas Type A is for medium and soft
rubbers where a blunt tip is used. There is a range in which both scales overlap, and
theoretically, both methods should work. In order to test the hardness range of Varioshore
TPU I printed a bunch of these small plates that are 3mm thick. The ISO standard for harness
testing asks for a minimum material thickness of 6 mm, so I always stacked two on top which
is specifically allowed. Let's start with Shore D, so the scale for
the harder materials. You press the durometer on the material, ideally with a specified
force, and usually read the measurement after 15s. To get a feeling for that scale, let's
start with standard 3D printing materials. PLA was the hardest with 78, then came ASA
and Prusas PC-Blend with 73 and PETG was even a bit softer at 70 Shore D. My cutting matte
is around 60 Shore D. Than we made quite a big jump with 46 Shore D for Extrudrs medium
hardness TPU. Next, we finally get to Colorfabbs Varioshore TPU. Parts printed at 190°C, when
no foaming happens, measured in at 35 Shore D. The samples printed at 200°C already were
significantly softer at 25 Shore D and we further decrease the hardness at 210°C with
20 Shore D. You can also definitely feel that with your hand when you bend the material.
The 190°C sample is still quite firm, whereas the 200°C sample that's already a bit foamed
up is way more compliant. Now it gets interesting because at 220°C we've seen the highest degree
of foaming. Will this also be the softest sample? I measured 16 Shore D and as expected,
the sample printed at 230°C was already a bit harder at 19 Shore D and on a similar
level as the 240°C and 250°C samples. The only material I had that was even slightly
softer was Diabase X60 TPU, which measured in at around 14 Shore D, which is already
interesting. X60 is soft like Spaghetti, and not the one cooked al-dente, and I wasn't
able to print it on my Prusa, not even to speak of a Bowden-style printer like the Ender-3.
This material requires a special extruder for flexibles like the OmniaDrop of which
I have one on my E3D Toolchanger. Though, if we print the Varioshore TPU at the ideal
220°C we get almost the same level of softness but it's way easier to handle! Think about
that! I repeated the same tests on the Shore A range,
where the measurements are usually taken instantaneously using the drag indicator. I didn't even bother
testing the standard materials because they are all outside the range. Extruder Medium
Soft TPU was the hardest and measured 95 Shore A. Then came all of the VarioShore results.
They were starting at 92 Shore A for the samples printed at 190°C. The softest piece again
was the 220°C one with 65 Shore A. The parts that were printed even hotter measure in at
around 70 Shore A. The black spaghetti, Diabase X60, tested, just as advertised at 59 Shore
A so again just slightly softer than our 220°C Varioshore TPU. Pretty cool or what are your
thoughts? So, we were able to double the volume of Varioshore
TPU by foaming it up, but does that mean our hardness halved? Let's take a look at the
Shore A scale which is the one we should use for this material. We've previously learned
that the shore harness values correlate with how far the indentor went into the material.
If we calculate the indentation depths from the measured hardnesses, we have 0.21mm of
indentation for the unfoamed material and 0.87mm at the maximum foamed level. This means
that we not only doubled the softness but even more than quadoupled it! Pretty cool
and again confirms the scaling laws for foams that say, that foaming level and mechanical
property are usually not correlating linearly, but at, for example, half the density, you
lose more than half of a mechanical property. More on that in the Light Weight PLA video
and if you find these investigations interesting, then also consider subscribing and clicking
the notification bell! Let's now also quickly take a look at a way
we can vary the softness of materials with simple slicer settings. 3D printing allows
us to print parts with variable amounts of infill, which results in variable hardness
for TPU parts. To quickly investigate that, I printed samples with different degrees of
rectilinear infill in Extrudrs Medium TPU and measured the Shore Hardness. As expected,
Shore Hardness A and D decrease with lower infill values, especially between 30 and 10%
reaching a softness almost comparable to the maximum foamed Varioshore TPU or Diabase X60.
Though this method is not always feasible because wall thickness and orientation will
effect those values quite a bit. This investigation is by no means complete, and different infill
patterns will give you different results, but I think I could show you the general idea.
So what's Colorfabb's Varioshore TPU now good for? For once, I see it as a material that
you can use if you want to print something really soft, but your extruder cannot handle
spaghetti filament. Also, you can basically double your printing speed for flexibles because
at the same feed speed of the extruder, twice the material comes out of the nozzle. Then,
the aesthetic with the nice, matte textured surface finish might be a good base for painting
because the color can grab into the surface and things like markers don't smear out like
on other 3D prints. I can also think of special applications where you could vary printing
temperatures within a model to create some pretty exciting part properties, for example
for shoe soles or bike grips. Then there is the density of the material. In the foamed
up state, it is around 0.5 to 0.6 g/cm³ which make parts printed with this material quite
buoyant. Especially interesting if you need to print something 100% dense, because you
need to make sure that no water can seep into the infill. With its softness and therefore
toughness, low density and closed porosity it might be a great material for parts that
need to float and perform a function. Because many asked after the last video on
foaming materials, I quickly wanted to find out if the parts really don’t absorb water
and not act like a sponge. For that, I weighted parts at different forming levels before and
after I submerged them in water for 14h. Even though the foamed up parts absorbed slightly
more water, in this case, 1% of their weight, they were not like a sponge. I suspect that
the internal gas bubbles are mostly not connected, which makes it a closed-cell foam. Therefore
this material may be a good solution for things that need to float and where you don't have
to be afraid that your model absorbs water or leaks into it.
Speaking of things that should or should not float. I just listened to an audiobook about
submarine warfare in WW2 called "Thunder Below". I was really excited to hear this story because
I also listened to a bunch of Tom Clancy's audiobooks over the last years, especially
noteworthy "Red Storm Rising". Clancy goes into great detail on today's submarine technology.
"Thunder Below" by Eugene Fluckey, with its WW2 setting, was especially interesting in
contrast because I learned where tactics and technology come from. Now here's the deal,
Audible is sponsoring this part of the video and offers you a 30-day free trial in which
you can listen to one of those or really any other audiobook completely for free. You'll
also get access to their plus catalog with more exclusive audiobooks, podcasts, and other
Audible originals. Support the channel and visit Audible dot com slash cncnkitchen or
if you're in the US, text CNCKITCHEN to 500 500. Over the last months, I've been going
on quite a lot of walks outside where Audible's great selection of audiobooks always kept
me entertained and educated. I really enjoyed "Thunder Below", an exciting and interesting
story about how the USS Barb revolutionized Submarine Warfare in World War 2. Support
the channel and get your free Audibook now! Just visit Audible dot com slash CNCKITCHEN
or text CNCKITCHEN to 500 500. No risk involved, and you can keep all of your audiobooks forever
even if you, at some point, decide to cancel the service. Thank you, Audible, for sponsoring
part of this video! Thanks for watching everyone, I hope you're
all doing well! If you found this video helpful than leave a like, share it with the community
and make sure that you're subscribed for more. If you want to support my work, head over
to Patreon, become a YouTube member or use the affiliate links in the description. Go
check out my other videos if you currently have more time than usual and want to educate
yourself. Stay healthy, auf wiedersehen and I hope to see you in the next one!
