Hello there,
This video is about 3D printed breathing masks.
Seeing as how we’re going through some hard
times now battling a weird virus that’s
come around, I’ve started working on designing
and building a breathing mask that could filter
out virus and bacteria as well as other particulate
matter floating in the air.
In the process of doing so I’ve actually
learned a lot about how breathing masks are
supposed to work and the process involved
in filtering out the contaminants that you
do not want to breathe in.
I wanted to make this video teaching you how
I used what I learned to build this mask and
the process I went through to design and build
it, as well as a general warning regarding
some 3D printed mask designs that are out
there.
Since this pandemic began, there have been
a group of people that no doubt have really
good intentions, and have designed breathing
masks that can be 3D printed.
The problem though?
They don’t really work.
Not only that, but they can be dangerous in
a completely different way.
By giving people a false sense of security.
Now to understand why that is the case, we’ve
got to understand how 3D printers work, and
how breathing masks work and protect your
respiratory system from the environment.
FFF or FDM 3D printers, your typical 3D printer,
create objects by placing thin layers of material
on top of one another.
This process is quite imperfect and can leave
gaps within the material that can let air
and other particles through.
It may not look like it to the naked eye,
but the surface of this 3D print is actually
full of tiny holes.
Here are some photos I took with my microscope
to illustrate the point better.
The layers that make out a 3D print can have
gaps between 6 and 8 microns thick.
Viruses like the one going around right now
are 200 times smaller, around 0.08 to 0.03
microns in diameter.
Of course, this issue would be resolved if
you’d have access to a powder-based or resin-based
printer with medical grade materials.
But most people printing these masks don’t
have access to such equipment.
Another problem with the surface left by the
3D printer is that it is rough.
And because it is printed with normal PLA
or ABS, it is a great breeding ground for
bacteria and they’re rather hard to clean
and disinfect.
Now, all of these problems can be overcome
rather easily by changing the actual surface
of the 3D print like I did with this mask.
This process is rather simple, and I’ll
go about explaining the steps I took to do
this when I show you how I built this mask.
But before that, there’s another issue we’ve
got to discuss when talking about breathing
masks, and that is the way they actually work.
Masks like this 3M N95 mask I’ve got here
or this surgical mask work by having a layer
of intertwined fabric that will stop particles
going through it.
Like I mentioned previously, a virus can be
really really tiny, but here’s the thing,
there needs to be a balance between breathability
and filtration.
It is impossible to make a filter that will
catch 100% of particles because it will also
not let enough air through it.
These masks overcome this not by having really
dense filters, but by having multiple layers
of filtration.
So a particle attempting to enter the mask
would be like an arrow being shot through
a forest of trees.
The arrow will travel a couple of meters but
it will eventually hit a tree on the way to
the target.
We can get our filtration material for our
mask from an already existing surgical or
N95 mask.
It is also possible to use a vacuum cleaner
bag or a HEPA filter.
But in this case, I wouldn’t recommend it
unless you know what you’re doing.
HEPA filters usually come with a rating written
on them, depending on the type of filter and
its intended purpose, it might not provide
enough filtration.
You could overcome this by doubling up the
filter.
But I’d say to better be safe than sorry
and stick to filer materials that you already
know will work reasonably well in the environment
you plan to use the mask in.
Another very important thing when discussing
the way breathing masks work, that might actually
be the most important thing about the way
they work, the seal.
There’s a very important difference between
surgical masks and N95 respirators like this
one, and it is the fact the N95 respirator
will actually create a tighter seal around
your face and nose, while the surgical mask
is just loosely fitted.
This is ultimately the thing that makes surgical
masks not suitable in an environment where
viral particles might be floating around the
air.
There’s nothing stopping the air from entering
your lungs through the gaps that the mask
leaves around your face.
In comparison, an N95 mask has a much tighter
seal around your face, it isn’t perfect,
but it’s much better.
Now, this is a category where 3D printed masks
fail spectacularly at.
There are a lot of examples I could cite here,
and there is one in particular I’d like
to discuss about.
But I will leave that for the end of the video.
I would like to show you how I built this
mask first.
The way I got about solving this problem with
this 3D printed mask was by testing multiple
rubber materials that I could put around the
edge of the mask to create an air tight seal.
I ultimately settled on this rubber window
padding tape that’s used to prevent air
from entering through tiny gaps in older windows
that don’t seal well enough.
It works surprisingly well for this purpose,
and might actually work to adapt other 3D
printed masks as well.
Now I feel like I’ve been talking a lot
and this introduction is long enough already,
so let me show you how I built this mask and
continue detailing some of the issues with
3D printed respirator masks later.
The first step is of course printing the model.
The model will come out of the printer rather
rough and with an unequal surface.
It doesn’t really matter how good your 3D
printer is, we’re worried about micron level
gaps in the surface that are impossible to
avoid using FDM 3D printers.
What we’re going to do is change the surface
of the print entirely by sanding it, filling
it in and painting it with an acrylic paint.
There’s a great tutorial on how to do this
by “juresnip”.
I’ll be linking his video in the description.
I will of course also show you my own process.
In order to solve the issue, the print needs
to be sanded.
The best way of doing this is wet sanding
under tap water.
If you sand plastic without water, you risk
melting and deforming the plastic itself.
You start out using rough sand paper and then
moving down to higher grit sand paper.
There isn’t an exact science behind this,
you just need to sand until you feel the surface
is smooth.
The next step is to add filler, Now, I would
usually use spray filler for this, but I was
unable to find any and I am now unable to
exit my home in search for some.
So instead, I decided to use universal filler
paste, usually used for filling wood.
I used a glove to do this, and I slowly rubbed
the paste all over the gaps in the mask, pretty
much covering the entire mask.
It’s ok though, because we will be sanding
this filler down, most of it will be gone
once we finish.
Once the filler has dried, we can start sanding
the surface.
It’s basically the same process as when
we first sanded the print, but this time we
will NOT be using any water.
In this particular case, combining the filler
with water would make it pasty and unusable.
This wouldn’t be an issue if you’d be
using spray filler instead of paste filler.
After sanding, make sure to open up the gaps
on either side of the mask that will allow
us to mount the strap holders later.
After sanding, comes painting, I wasn’t
able to film the painting process but it’s
pretty straight forward.
I applied two even layers of plastic primer,
and then two layers of acrylic white paint
that would dry out to form a hard shell around
the printed part.
Now, for an application like this one, I would
recommend using acrylic lacquer as well, to
add an extra layer to the part that can be
easily cleaned and disinfected using Isopropyl
alcohol, chlorine or hydrogen peroxide.
The next step would be to apply the rubber
seal around the edge of the mask, but in order
to do so, we need to sand the edges first
because filler and paint would have gotten
to them, and we need a clean surface to glue
the rubber seal to, otherwise gaps might form.
We now need to get the rubber window seal
and cut it to length, you don’t need to
be too precise as we will be cutting it to
final length later.
We can now start gluing the rubber seal around
the mask.
I will be using Cyanoacrylate glue for this.
But a non-toxic silicone might be more suitable
for this purpose.
I started at the bottom as I saw this to be
the best position to leave the final gap that
will need to be glued at the end.
You need to go slowly and move around the
edge of the mask, making sure to align the
center of the rubber seal with the edge of
the mask.
Once you get to the nose section things get
a bit tricky, you’ll need to apply pressure
while twisting the seal around and then hold
it in place.
It might take a few tries; you can always
practice without putting any glue in place
first.
Once you get to the end of the run, you can
cut the seal to length, make sure to cut it
straight so that both ends meet against each
other.
You can then apply glue and press them against
each other.
You can apply more glue in the interior of
the seal to make sure the seal is sturdy enough.
In the 3D files there will also be a bunch
of pins and strap holders that you can print.
The first step is to glue the pins in place
in the gaps that are on either side of the
mask, these pins will serve as guides for
the strap holders.
Next, make sure to test out the position the
strap holders will go in, and then apply a
liberal amount of glue and glue them in place.
The holders should be slightly angled upwards
and downwards.
Now we’ve pretty much finished the mask
itself, and we need to move on to assembling
the filter.
There are 5 main parts to the filter assembly:
The main body screw, the cap, the ring, the
filter itself, and a rubber O-Ring.
Before assembling the filter, let me show
you how it works.
In order for the filter to do its job, it
must not allow particles to pass through any
part of the assembly except the filter material.
To achieve this, there is a ring that presses
against the filter material and it doesn’t
allow air to go through.
The ring is pressed in place by screwing in
the cap.
Plenty of space has been designed inside the
main screw to put a filter grid inside like
the ones used in HMEF filters.
(Scene 28)
The first step is to place the filter material
over the main body and then place the ring
on top of it.
We’re going to press the ring tightly against
the filter material.
After we’re sure the seal is tight enough,
we can go ahead and cut all the excess filter
material off the edges.
We then proceed to screw in the cap, making
the ring press against the filter even tighter.
Now, we could screw the filter into the mask,
and if we intended to use glue or silicone
to seal it permanently on, that would be ok.
But the point of the screw in filters is to
make the mask reusable.
After all, you can make more screw-in filters
easily, but making masks isn’t as easy.
In order to preserve the capability of screwing
in the filter without sacrificing the air
tight seal.
We need to add an O-ring before we screw in
the filter.
A custom-made rubber O-ring would be perfect,
but In my case I lack the materials to make
it.
So instead, I decided to use a replacement
material that works just as well, Funky foam.
It is a rubberized foam material, so it shares
many of the same properties.
In order to cut the O-ring to the correct
dimension I modeled and printed this stamping
tool.
Now, something important to remember about
O-rings, is that they don’t seal properly
on their own.
They require some kind of lubrication in order
to produce a good seal.
There exists special Vacuum Seal and O-Ring
Grease, but for our DIY purposes standard
silicone grease will also be able to maintain
the seal, it just won’t last as long.
Which isn’t really a problem because the
filters are designed to be changed, and the
mask cleaned and disinfected after a couple
hours of use anyway.
Now with all that, we’re done building the
mask!
Of course, there are a lot of improvements
in the building process I did not show.
Like actually filling, priming and painting
the interior of the mask as well as the filter
caps.
And I also didn’t add lacquer to the exterior
in order to be able to make this video on
time.
The filter area itself seemed good when doing
the math, but once I wore the mask I noticed
it’s quite hard to breathe.
It’s fine if you’re breathing in slowly,
but it can cause trouble if you take deeper
breaths.
I will modify the design to have larger filters.
Version 2 of the mask will hopefully be ready
when I publish this video.
The filtration capabilities of the mask depend
on the filter material of your choice.
I of course recommend using the same filter
material that tested respirator masks are
made out of.
I have tested this mask for pressure leaks
around the edges, and the seal was able to
maintain the pressure while the mask was on
my face.
So I’m confident this mask won’t have
the same issue that many other 3D printed
masks have.
Now, like I mentioned before, 3D printed respirator
masks fail spectacularly when it comes to
the seal around the mask.
I think the most egregious example has to
be the mask made by Copper3D, I mean, look
the gaps between the nose.
This mask has even been marketed in many news
articles, blogs, and forums, if you’re in
the maker community you’ve no doubt seen
it around.
They even claim they used patented technology
and advanced R&D to make the mask with various
partners.
Like we haven’t seen 3D printed masks before
that work in this exact way, for cosplay or
other purposes.
And of course, they claim that in order for
the mask to work you need to buy their special
copper filament.
Now, Copper has been shown to have antiviral
and antibacterial properties, But I haven’t
been able to find any conclusive studies that
the filament they sell has any of the same
properties.
In fact, the claims made by the makers of
this particular mask prompted authorities
from multiple ministries of health to send
out notices warning against the use of 3D
printed masks.
On screen I will put one from Chile’s ministry
of health titled “3D printed masks: High
risk of infection, false sense of security”
They mention that even though people may have
the right intentions trying to help people
by printing these masks, they are putting
people at risk instead.
So be careful.
So, while I was in the process of gathering
the footage and editing the video, I actually
went to the Copper3D website and this is the
announcement that now pops up if you try to
visit the website about the mask.
They actually tell you; you should not use
this mask and they’re pretty much admitting
it isn’t safe.
They even say it isn’t intended to be printed,
sold and used by anyone.
So, they state they do not recommend using
or printing it anymore.
Even though the mask has been marketed and
publicized everywhere as something you can
print to help people out with the title “Hack
the pandemic”.
Yeah, it doesn’t actually work and it’s
actually quite dangerous.
I have designed this mask specifically to
be safe and be able to be used in an environment
where the air might have a viral or bacterial
load.
That’s why I changed the surface of the
3D print, I placed material around the edges
of the mask to create an air-tight seal around
the face, and designed screw in filters with
O-rings that wouldn’t let air into or out
of the mask unless it passes through the filter
fist.
Even though I’m confident this mask will
offer more protection than your standard surgical
mask, It should be used as a last resort if
you do not have access to mass manufactured
protection equipment.
While 3D printing masks may help short term,
it isn’t really sustainable long term, especially
keeping in mind the time-consuming process
of building one that actually works.
Many people are printing these objects not
knowing how to help or what to do with them.
In the past week I designed a respirator mask
meant to be used with this Venturi’s valve
designed by Filip Kober.
I received many messages asking me, after
they’ve already printed them, asking me
how to use them and what they’re for.
I know it’s well intentioned, but you should
contact your local hospitals and ask them
what they need first.
One of the safest and most useful things you
can 3D print and build are face shields.
Even Prusa research designed their own and
made the files available for everyone to print.
I will link them in the description.
Now with all that.
I hope you learned something.
Stay Safe.
Bye
