So the iTopie i3 is almost done, and what
typically takes the longest is wiring everything
up properly. Now, i know that part is not
fun, it’s not rewarding, at least not for
me, and it’s like this huge threshold between
having a machine that looks finished, you
know, with all the parts mounted and ready
to go; and a machine that actually works.
But at the wiring stage, you are actually
setting the foundation for a machine that
works reliably and is open for future modifications
without it ending up as a total hackjob. So
today i want to give you a rundown of what
wiring to use, how to manage it properly and
how to connect everything up.
And i need to start out with a disclaimer,
basically, as always, use some common sense.
I can give you the basics of “good practices”,
but ultimately, you’ll be responsible for
how you set everything up. Cables can overheat
and potentially catch fire if they are sized
improperly or wear out due to improper strain
relief. This guide can help you avoid the
most common mistakes, but please don’t sue
me if you make one that i didn’t cover.
Alright? Let’s go.
Let’s start out with what cables to use,
first of what wire gauge to use for the various
functions in your 3D printer. So there’s
basically three tiers of components you’ll
see. There’s sensors, fans and motors, which
use practically no current, then hotend heaters,
with a 12V heater drawing close to 4A, and
a heated bed, typically around 12A. So what
i like to use for, let’s call it tier 1,
is ethernet cable, for a few reasons. First
off, it’s cheap. Unshielded Cat5 cable is
all you typically need and it’s like 20ct
per meter. And that gives you 8 wires, twisted
in pairs, which is great for what we’re
doing because not only are they nicely bundled
up, having them twisted keeps any electromagnetic
interference in check. The one thing you should
keep in mind, though, is that you want to
get the flexible version and not the one with
solid wires, more on that in a second. Even
the cheaper 26-gauge wires, or 0.13mm², are
rated for around two amps, which is plenty
for a fan or sensor, and just barely enough
for a stepper motor. The way you should use
the twisted pairs is to have one wire carrying
the current to the component and the other
taking it back. So in case of a fan, that’s
positive and negative, for a motor, that would
be the two connections from each coil, which
are the black and green as well as the red
and blue wires. For an endstop, signal and
ground, and for a thermistor, obviously the
leads of that. What’s also nice about ethernet
cable is that, because it has those two layers
of insulation, it tends to keep its wires
in a larger radius compared to individual
wires, which is good for keeping them from
wearing out due to the repetitive bending
motion you’ll see when printing. There are
two factors that decide how well a cable is
suited to being repetitively bent, one is
the insulation, in this case plain PVC, not
ideal, but usually good enough, silicone would
be better, but is much more expensive. And
the other factor is the makeup of the copper
conductor. You can obviously get solid-core
and stranded wire, and when you bend them
both in the same radius, the surface of the
solid wire is going to stretch and compress
much more than each individual surface of
each strand. Solid wire is perfect for bending
it into shape and then leaving it, but stretching
and compressing cooper too many times will
break it. So the finer the strands, the more
suitable a wire is for being moved around.
Now, again, the Ethernet cable i’m using
is reasonably fine-stranded, but an even better
choice would be specifically-made cables that
have extra fine strands, especially when you
need them to repeatedly bend around tight
radii, which i’ll show you later on how
to avoid.
Ok, so second tier components, heaters. Now
i also use Ethernet cable here, but a single
conductor is not enough for a 12V, 40W heater,
so i usually use two wires and a total of
two pairs here. Now, you don’t just want
to use one pair for positive and the other
for negative, you actually want to the plain
wires together for one phase and the striped
ones for the other, that way you have the
forward current twisted to the return current.
If you want to use a single wire instead,
you’ll need something around a 22-gauge
or 0.75mm² wire. Since the heater typically
isn’t on for extended periods at a time,
but instead pulsed, you do have some leeway
there.
Now, for tier three, the heated bed, you’ll
need something a bit more massive than that.
And for a typical PCB heater, I’d actually
recommend using a thicker wire than needed
to minimize losses in the wire itself, as
that will take away much more of the available
heating power from the bed than you’d expect.
As such, at least something around 12-gauge
or 2.5 to 4mm² is what i’d recommend using.
What usually fits that bill is speaker wire
because wannabe “audiophiles” will completely
oversize their wiring several order of magnitude
to get that last bit of “crispness” out
of their speakers. But just make sure the
wire is, again, fine enough, and actually
copper, as the cheaper copper-clad-aluminum
wires will break way more easily under stress
and fail over time in most connectors. Another
good alternative is silicone wire, as used
in electric RC cars, it’s a good bit more
expensive, but is actually a perfect match
for the job.
Now, next up, how do you route those cables
to your components? What i actually see people
doing is checking at which spot the cables
need to be the longest and then just cutting
them to that length. Which isn’t really
ideal, what you’ll get is this caterpillar
effect and the cable might end up going anywhere.
A better way to handle it would be to create
an anchor point somewhere in the middle of
the axis and routing the cables there in a
half-loop, so that you’ll never get the
cables completely stretched straight at any
point. Of course, how you can route them is
going to depend on your exact printer, but
in any case, having them in any sort of loop
or half-loop is always going to be easier
on the wires and easier to manage. Now, you
still want to make sure the wires don’t
end up kinking or flexing in the same spot
over and over, so you still need to take care
that the point where the cable is fixed to
the moving and standing parts has some sort
of support - this can be a bit of filament
or simply the wire’s insulation itself.
You just want to keep it supported at the
most critical spots.
Now, to really get it not only looking a bit
more nicely, but also out of the way and bundled
together more tightly, there are two more
options: Nylon mesh sleeving and drag chains.
Drag chains are great, but they can be a bit
tricky to use right, so let’s start out
with Nylon sleeving: You can get it in all
sorts of sizes, and it keeps your wires out
of sight, bundled together and somewhat supports
them at the same time. By the way, it’s
the same stuff as used by computer enthusiasts
and power supply manufacturers.
Your other option are drag chains, and on
the iTopie we actually used both. So a drag
chain is made to used like this, not like
this. Its job is basically to keep the wire
in a precisely defined position and to keep
the bending radius constant. Though the problem
is, if you want to use a drag chain, you have
to plan for it, because typically you aren’t
going to have the proper surfaces to mount
it to to get that rolling motion. They come
in two version, one opens up to let you just
drop in your wiring, the other stays closed
and you’ll need to push the wires through
by hand, which might be a tight fit if you
have any sort of connector on their end.
What’s also important to keep in mind with
them is to only use a zip tie for the wires
on one end, not both, or you might end up
stretching, compressing and breaking the wires
as the drag chain moves, so always leave a
bit of slack on one end before anchoring it
down again.
Now what i like to use for keeping the wires
exactly where i want them are these little
stick-on anchors, again, they’re really
inexpensive, links in the video description,
by the way, and they give you spots to zip-tie
any wires to without having to drill holes
or zip-tie around any larger components. You
can also get them with a reusable twisty thing
already attached, but those don’t hold the
wires down as tightly, which can be ok for
a lot of places.
Now, connectors are easy to overlook. If you’ve
got cables that already have all the connectors
on them, you’re good to go, but it’s not
too hard to add your own, either. And i’m
not going to go into full detail on how to
use these tools, i think there are plenty
of videos on Youtube already, but i can show
you what to use. I’ve personally settled
on two types of connectors, as they are compatible
to what is typically used on controller boards
and are easy to crimp yourself. The first
type are what are called Dupont connectors,
they are 1/10th of an inch pitch crimp connectors,
they don’t have any keying and they will
pretty much universally fit any other 1/10
inch connector, whether it’s these white
types, as used for computer fans or the more
complex, locking types as seen on some boards.
Oh, and you can use male or female pins with
them, so you can really easily craft extensions
or disconnect points. All of these use the
same crimping tool to get the contacts attached
to the wire, and are all rated for about 2
to 3 amps, which is perfect for all those
tier one consumers including motors. Now,
for tier two, heaters, simply using two pins
in a connector is valid, but you’re not
going to find any board that has that sort
of a connection. So what i like to use for
hotend and bed heaters instead are these larger
crimp connectors, again they’re a family
of connectors that span anything from male
and female blade connectors, wire end crimps
or spade terminals for attaching to a power
supply. These will carry as much current as
the wire you crimp them to.
Now, both of these crimping tools are great
to have and they make properly wiring a 3D
printer or anything else just so much easier.
I paid about 20 buck for each one, with a
big set of connectors, and that was totally
worth it.
So one last tip i want to give: Make wiring
plans and label your cables. It’s super
easy to do, just write down which wires in
which cables you’re using for what functionality,
and since they are color coded, you know exactly
where to look. And even the simplest plans
can help you out a ton should you ever want
to modify anything or have to look for an
issue down the road.
This video is sponsored by Aleph Objects,
Inc., a Free Software, Libre Innovation, and
Open Source Hardware company headquartered
in Loveland, Colorado, USA and makers of LulzBot
desktop 3D printers.
Watch my reviews of both LulzBot 3D printers
here and check the links in video description
for more info on the machines straight from
Aleph Objects.
So if you enjoyed this video, leave me a thumbs,
if you didn’t down, and you want to support
the general thing i’m doing here, consider
subscribing, using the Amazon affiliate links
from the video description or directly throwing
me a dollar or two over on Patreon. And that’s
it for today, thanks for watching, and i’ll
see you in the next one.
