In this video I'm going to see how far we can push flexible filament on bowden printers,
and I've got a couple of different filaments to show you.
Let's go.
Before we begin I want to just catch up with where we are at with TPU after my first two
videos on the subject.
In video 1, I explained that you can print standard 95A TPU on a bowden printer like
the ender 3 series with very little issue if you do some initial calibration tests first.
In video 2, I went a bit further by testing if you can improve the quality without increasing
the failure rate, and we ended there with a few key premises that I think are really
important to lay out again briefly especially if you haven't seen it or it was a while back,
the video is now about 7 months old so a recap won't hurt.
Firstly, we need to think of TPU in terms of pressure, rather than print speed or whatever,
we are pushing an elastic material down a tube and so we lose the one to one ratio of
movement at one end of the tube to movement at the other, pushing at one end increases
the pressure at the other and this causes the molten material to be extruded out of
the nozzle.
Secondly we discovered by accident that there's an optimal speed, presumably having thought
about it since then it's probably an optimum flow rate, that we should print at for the
best finish and this is higher than we might be led to expect.
And finally related to point one, well, this one goes against the grain but it continues
to be true in practice, when you have constant extrusion over a long period with an elastic
filament you build up the pressure, and most failure modes with this filament involve the
pressure becoming too high, in plain terms either the wheels will slip or worse the filament
ejects from its proper path and the print fails.
You should use retraction.
Just use retraction.
🕷 Does this show up as a spider?
Just wondering.
🕷🕸🕷🕸🕷. Anyway.
So now we're up to speed let's move on to some new exciting stuff.
In this episode I want to explore the limits of bowden as much as I can, for which I need
a fair few types of filament.
Turns out, flexible filaments that aren't so called 95A TPU are pretty hard to get hold
of here in the UK, so this is why I worked with Wedge 3D for this video, if you remember
I mentioned them in my PEI video, they reached out to discuss how they could help with this
video and they managed to source a new type of filament that I'll show you in a bit, but
also they provided me with a tonne of samples to test in order to get the results I needed
for this video.
So the video is marked as sponsored.
Let's talk shore hardness.
When you buy your 95A tpu, the 95A is referring to a specific metric, a metric that describes
the hardness of a material.
It was invented officially by some guy called Shore, aha that's why it's called shore hardness....shorely
that's obvious?
So the method of testing is actually pretty simple, you use something proddy to poke at
a specified size lump of a material and see how far it moves when you apply a specified
force to it.
It's not that simple though, I mean of course it's not, why would it be?
What you see here is a sample of fiberlogy fiberflex 40D..I struggle to remember the
names because they're all fiber fila flexi flex and it drives me insane.
This is not 40A, if it was, you wouldn't be able to feed it into an extruder easily, let
alone actually print it.
It's 40D.
So there's different shore hardness scales.
Lots.
Of different.
Shore hardness scales.
I'll show you a diagram comparing A with D, I get the impression it's kind of rough, and
why is probably because of the way A is measured.
If we look at the tip of a D meter, it's a pokey thing all the way to the tip, but the
A is a sawn off pokey thing.
So that's why D is on a different scale to A, oh and the force you apply to a D is higher
too (hah, you were going to correct me and say "no it's force"!).
I feel like for a lot of A rated materials if you used the D probe...behave...you'd probably
poke a hole all the way through the test piece.
With your D probe.
So I guess we can rank some flexible filament, I have here your standard 95A and yes I'm
doing air quotes, but it's probably close enough to the nearest 5 or so, then I have
40D which is about equivalent to about 87A, so a fair bit softer than 95A, and we have
also 30D which is about maybe 78A give or take, but what's evident is that they don't
match perfectly because if I bring in this recreus filaflex that I blagged off a mate,
this is 70A and it is way softer than this 30D.
This stuff feels like pants elastic, I'm serious.
That's Underpants btw, to the USA fans.
We don't have elastic trousers here, well...maybe we do, who knows.
So which ones can we print?
Well all of them of course...do you even know who I am?
DO YOU?
I AM THE TPU EXPERT!
Ahem.
So...we can print all of them on a decent, well even basic direct drive setup.
But...bowden is another matter.
Where's the line?
How far can we go?
You might be wondering why I have a tray full of printed blocks of these samples, well I'm
waiting for something to arrive...
hang on...
This is a shore durometer, a type A. It's pretty cheap, just like my joke, but it seems
to work just fine.
Let's test.
I know some of you really like my music so I'll shut up and let you listen to it.
(A montage of poking bits of squishy plastic follows to the tune of Gymnopedie No. 3.)
I thought that was pretty cool - I guess they are pretty accurate with their ratings after
all, I didn't expect that especially for the various 95A filaments, they dont even all
feel the same or print the same.
Weird.
This 70A stuff though, either it's not 70A but 60A, but I double checked and it is apparently
70A.
I believe I may be just unable to extrude it.
I will
try it on the artillery's titan extruder during edit, I guess.
So anyway I made this thing a while back, it's a basic but useful model for testing
out flexible filament, it uses nearly no filament up which is good because this stuff is expensive,
but it also combines quite a few failure modes in one model while also generally printing
at least most of the way before fails happen.
I'm going to use the neptune 2S and Steve for the bowden tests, and Janet for the direct
drive tests, we have a pretty basic direct drive here with ...ah let's just get on with
it.
95A is not a problem.
But I did observe in the neptune 2s review that the neptune is better than the steve
at this TPU thing, but if you didn't watch that then I concluded it's either the extruder
or the capricorn, hehe, I have an answer for you I think later.
40D is also not a problem for the neptune or steve.
Interesting.
Steve is a bit stringy but this is actually pretty normal.
Given that the 40D comes in around 85-90A that's quite a big deal, so it's worth pausing
on that for a moment.
We've gone from a platform of "you need a direct drive to print flexibles" to being
able to print softer than normal flexibles without a problem.
If you're yelling "prove it by printing more" then hold on a second.
30D time.
Neptune...no problem!
Steve....generally fine too!
Okay then.
So, do we need a direct drive at all for flexibles?
Yes.
Yes we do.
This is the 70A and it does not play at all with the dual gear bowden extruder on the
neptune 2.
It's quite funny, at least so long as it's not jamming the hotend.
It's tricky to get the direct drive to print this stuff too actually, but here's a handy
tip if you're ever stuck with TPU, go look at the manufacturer's website, they might
actually have a tonne of useful information including printing parameters.
They didn't work for me, but they got close, I basically halved the speed and it printed
perfectly, or close enough, to make this mat here to hold things.
Like phones, or whatever.
This stuff is SO soft it feels like that weird stuff eggs have under the shell.
Oh and it's not TPU.
It's TPE.
So...I learned that.
Measuring it is hard too because even at 100% infill, with 126% flow rate I think it is,
it still lets the needle sink in.
So where are we?
Well, I tried changing the tube on steve, to capricorn.
This is genuine capricorn, and it ought to print tpu better or with less stringing or
at least something?
But nope not really, about the same.
It may have benefits, but I couldn't reproduce anything in this specific test.
Of course, let's not forget it can print at a higher temperature than standard PTFE so
it's worth having anyway.
So...I would conclude that it's the dual gear extruder that's doing the work here when it
comes to improving the TPU print quality.
Interesting.
I think I have one last thing to cover.
Oh wait no, two.
This is mattflex.
It's flexible, and matt.
The sample didn't look that exciting until it was printed, and I noticed it looks so
cool, and prints so impeccably even on a bowden, that I got straight on to wedge3d and asked
for them to find me a reel of it, which I had to wait for as it's super new, and needed
to be obtained from fiberlogy themselves, they have it in stock now and that's probably
my fault.
I printed some really cool stuff with this though, this is for my bike handlebars, and
this is for no reason at all.
I will be doing all sorts of grips with this stuff as soon as I have time to design them.
So.
One last thing on this episode.
Why does 40D and 30D print so well on bowden?
Well I have no idea, maybe it always does, but I noticed something, I'm going to get
the microscope out again.
Look.
Ridges.
The D has ridges.
Am I going to...nope...absolutely not.
Not going there.
Okay so in terms of profiles, I will share the ones I've used
in this video, link below, but one thing I do want to try to convey in this and future
episodes, is that it's actually super easy to make your own TPU profiles.
I'm not some kind of TPU genius, I'm just familiar with the settings that matter.
And those are usually these ones.
There's another TPU video on the horizon, because there's more I wanted to cover but
couldn't in this one, so look out for it, but I've got a pretty solid schedule, so it
might be a few weeks away.
I've got steppers number 2 to do next, but there's a couple of product reviews that can't
wait between them so I'll try to increase my schedule a bit to get things moving, no
pressure.
Some good stuff though, so make sure you're subscribed!
Anyway that's it, I will see you next time, thank you for watching!