Hey, guys, Wally Renne here.
And I want to go over
a few things regarding
this 3D-printed mask
file that I have.
I have 400, seemingly,
different files on Thingiverse.
But they're all
essentially revolving
around a single concept.
And that is to be able to
3D-print something that
will provide a little bit
better protection than, say,
a t-shirt or a bandanna.
But in order for you to be
able to print successfully,
we have to go over some things.
One is the type of
printer you're using.
Most people, I
assume, are printing
with Fuse Deposition Modeling
Printers, FDM printers.
These are the cheapest, most
readily available printers
found at most high
schools, libraries,
and things like that.
Fuse deposition modeling
is a fantastic technology
that enables very
inexpensive prints.
So a mask like this will
print for probably like $3.
Now, if you're using
fuse deposition modeling,
we need to talk
about some things.
One of them is what type
of plastic are you using.
There is many, many
different types
of plastic for FDM printing.
The most expensive and
super-cool material
is something called TPU.
TPU is plastic polyurethane.
It is a flexible material.
I have a few TPU prints with
this mask and it's so awesome.
The downside to TPU is
that it's expensive.
And it's also difficult for
a lot of printers to print.
And it is extremely slow.
So a mass like this will take 18
to 24 hours to print at a TPU.
So most people are not
going to print at a TPU.
The other type of
materials are PETG, which
is polyethylene terephthalate.
PETG is found in
most water bottles.
And it is a very
bio-compatible type plastic.
You could print PETG
on most FDM printers.
It does require a higher
temperature and a higher
print bed temperature, as
well as extrusion temperature.
So you're going to
be at more like 240,
250, 260 Celsius
for the extruder.
And the bed's going
to be more like 80.
That's a really good
material to print from.
And it is super-durable.
And it's more resistant to
chemical sterilization agents
such as isopropyl alcohol,
and hydrogen peroxide,
and things like that.
PLA is what most people
are printing out of.
PLA is polylactic acid
derived from plants.
It's super inexpensive.
And it's probably the most
commonly printed material
on FDM printers.
Now, with that said, regardless
of what material printing,
there's some settings
that we need to go over.
And we'll talk about
that in a minute.
But with PLA, one
advantage of PLA
is that you could actually
use a blow dryer, because it
has such a low
melting temperature,
you could use a blow
dryer or a hot water bath
and basically dip the--
of course, without the
elastic and the gasket--
dip this in the water bath.
And then what you're going to
do is conform it to your face
because it'll be flexible.
It's a thermal plastic.
Now, with that said, regardless
of whether you're printing out
of TPU, PLA, or PETG,
you need to understand
something about layer height,
and infill ratio, and extrusion
rate.
So infill is the
setting that determines
how solid the print is.
The layers between shell one
and shell two, infill ratio
is how much of that's
actually filled in.
Now, typically when
we print with EPM,
we're doing a infill
of 15% to 30%.
But for this type of print,
where we want to be airtight,
we need to do infill of 100%.
100% infill, that's
super important.
There's been
numerous publications
in peer-reviewed
journals that talk
about how to print
with FDM printers
and have it be gas-tight, which
if your mask isn't gas-tight,
then there's really no
point in having a mask,
so infill of 100%.
The other thing that determines
whether your mask is printed
gas-tight is if
there's any micro-gaps
between the individual layers.
Typically, FDM printers work
by 100 to 200 micron layers
and it slowly builds up.
And the plastic is being
melted in layer-by-layer.
If there's gaps
between the layers,
then you're not
going to have a seal.
Well, there's been
some studies that
have shown that if you
have a flow rate of 98
or with an infill
rate of 100%, then
you're going to be gas-tight.
What is flow rate and
how do you change it?
Well, most printers, you
could change flow rate
on your slicer settings,
just like you can for infill.
Flow rate is basically
how much plastic
is laid down on each layer.
Now, typically, if you look
at, say, the Prusa Mark Three,
flow rate is going to kind of
default for PLA at about 95.
Studies show that you
need to be at least 98
in order to get a gas seal.
And what it's doing at 98 is
it's depositing extra plastic
for each layer to make sure
that the individual layers are
fused together in a more,
kind of, controlled fashion.
It won't be as pretty of a print
if you print with a higher flow
rate because you'll actually
see a little ripples in it.
But it's going to be
a more sealed print.
The other way that
you could change
the amount of
plastic laid down is
by your extrusion multiplier.
The extrusion multiplier is
very similar to flow rate.
And then you can set that to
1.5, 1.2, anything above one
and you're going to get a seal.
So that's kind of
going over that.
Now, a lot of people
said, hey, did
you know that your print
has a hole in it right here?
I'm like, yeah, of course I do.
And what that hole is,
it's for a rubber valve,
a exhalation gasket
to be glued in place.
The way that it
works is when you
place your filter in place,
the resistance of air coming in
is such that, especially if you
get a seal around your face,
there's suction pressure that
pushes this valve down airtight
so that all the air is
coming in through here.
When you exhale, it's going
to follow the path of least
resistance, which is this valve
that's just going to flap open
and air is going to release.
Now, you might say,
well, what if you're sick
and you're breathing through
here it;s exhaling out here,
is that going to protect people?
No, it's not.
So some people are actually
putting a vacuum bag,
HEPA filter, right here
in that exhalation port,
which is one extra
step that you could do.
Now, let's talk
about the filter.
This mask was designed,
it's written right here,
for the 700 filter.
Now, if you get third-party,
inexpensive ones,
I can't guarantee
that they're HEPA.
HEPA is a standard that
says that it's filtering out
99.7% of particles, 0.03
millimeters and larger.
If you compare that to, say,
the gold standard N95 mask,
N95 is only filtering out
95% percent of particles
in that same size range.
So it's actually,
essentially, an N99.
But like I said, I can't
guarantee the quality of these
if you're buying
nonofficial filters.
The real ones are
actually quite expensive.
The knockoffs are not expensive
at all, they're like $1 apiece.
So this snaps in.
Now, you might say, well,
what about the gap here?
Well, you could use hot
glue or an o-ring gasket.
But it fits really tight.
But it's still probably
not airtight so you
want to use something
that's going
to seal if you put this in.
So a couple of other
things about this mask.
If you're not heating
it and conforming it
to your face, which if you
are, be really careful,
don't burn yourself.
Just be super careful.
What you want to
do is use gaskets.
These are silicone gaskets
found at most hardware stores.
There's also medical-grade
silicone that you could use.
When you have the
proper plastic--
which, by the way,
this is marine elastic,
found at most hardware stores--
it's going to compress this
so much against your face,
you're going to create a seal.
And I have tested this mask
for a seal around my face.
And it does form
an airtight seal.
So that's one thing that
you need to understand.
You guys are probably
not going to be
able to test yourself
and get this fit checked.
But you need to understand that
this is something that needs
to be tight around your face.
And for me, that
required two layers
of gasket material here and only
one at the nose and chin area.
You could use window seal
material, single-sided foam
tape, neoprene.
Some people are using
yoga mat material
with double-sided tape.
And some people are
just heat treating these
and conforming them to their
face, things like that.
It's roughly about 15 inches
of material that you'll need.
OK, so moving on, people
have concerns, well,
this is a relatively
small filter
compared to some of
the ones from 3AM,
some of the respirators.
And so what we
decided is we came up
with a Roomba i7 filter.
Now, if you compare the sizes,
they are drastically different.
In fact, the i7's a
much better filter.
It's bigger all around.
And it actually has
this neoprene gasket
right here built in to
the filter, see that?
And then we designed
another mask.
This one is printed out
of PETG, so cool looking.
It's like a Darth Vader mask.
It's my favorite
mask that we have.
And, of course, you could
print the cover as well.
Actually, I got it on backwards.
Print it out of whatever
material you'll want.
So one thing that we need
to talk about with the I7
is a little feature
that's built in.
You see this flange here?
This neoprene
gasket will snap in
and press against that flange
and seal it all the way around.
So there's no need
to hot glue these in.
It's a super tight fit.
It's a really cool design,
better filter system
all the way.
These are expensive.
If you get the real
ones, the true HEPA ones,
they're roughly, I don't know,
for three, it's like $30.
So it's like $10 apiece.
Now, let's say you're
in a hospital setting,
you could just chuck this
at the end of the day
or you can use
hygiene peroxide vapor
sterilization of the filter.
For the mask,
itself, if it's PETG
you could soak the whole
thing in isopropyl alcohol
for five minutes to literally
just dump the whole thing.
Or you could spray it.
Down you could use hydrogen
peroxide, gas sterilization
of that as well.
Most people are just chucking
this and wiping this down.
It can get expensive with these.
The knock-offs are super cheap.
You get a packet
20 for like $20.
So they become more
like $1 apiece.
But, like I said,
I can't guarantee
the HEPA rating of those.
It's important to get
true HEPA filters.
So let's also talk about another
system because people are like,
well, I like this but
I don't like that it's
integrated with the mask.
So we have another mask.
Now, this one just
happens to be printed out
of medical-grade
autoclave-able resin
on a fancy printer that's
called a SprintRay Pro,
it's a DLP printer.
This whole thing
could be autoclaved
at the end of the day.
And you could snap in
a new system like this
with the valve properly placed.
We have them available for all
the various different filters.
So we have it for the
700 here and the I7.
We also have our
own MUSC design box
that you actually cut
your own HEPA filter out.
Now, there's some
dude online saying
that if you cut a
HEPA filter, you're
going to die from
fiberglass inhalation
or something like that.
Totally not true, most
modern HEPA filters
don't use fiberglass anymore.
And so you could look at
the MSD of your Hepa filter
to determine if it has
fiberglass particles in it.
Some MERV 16 still
have fiberglass.
But you don't need anything,
probably, above a MERV 13
for your filter if you're
buying giant filters
and cutting them yourself.
But, anyway, I hope this
clarifies some things.
There's a lot of misinformation.
Just to reiterate,
misinformation
is if you cut HEPA
filters, you're
going to die from lung
cancer, totally not true.
But like I said, check
the MSDS of your filter.
Misinformation number two
is you can't print airtight.
That's not true.
There is peer reviewed
publications and evidence
in the literature that
you can print airtight.
Misinformation number three is
that the Roomba filters are not
able to filter out particles
better than a wet t-shirt.
That's not true either.
A true Roomba filter
is HEPA rated.
And like I said,
it's basically N99
compared to a N95,
which is the standard
in the medical
profession right now.
So anyway, I hope
this helps, guys.
If you look at my Thingiverse,
there's a lot of files.
They're pretty self-explanatory.
There's easy print masks.
We really designed
these that they
could print flat on
the build platform
like this, that they
don't need any supports.
They are incredibly easy to
print on any printer now.
We basically modified the
design so that it's super easy,
anybody could do it.
The files, now, are
nothing like they
used to be when I first
originally designed this.
They've been re-iterated
at least 30 times.
So this is literally
mask 30 here.
So good luck and let me
know if you any questions.
