chances are you've thrown these things
in the trash without even knowing it
but if you use them like this they'll
spawn an electric arc hot enough to melt
any metal known to man and even turn
rocks into lava in this project we're
modifying a fire brick and some
flashlight batteries to build an
electrical arc furnace on a budget let's
start this project with a heavy-duty
Lantern battery in this alumina silicate
refractory brick the brick is three
inches tall four and a half inches wide
and nine inches long let's get to work
making the furnace by measuring
lengthwise and marking it three inches
four and a half inches in six inches
this is where it needs to be cut so it's
a good idea to draw perpendicular lines
with something like a combination square
to make it as accurate as possible now
get a mask ready because according to
the safety sheet silica dust is
something you really don't want getting
into your lungs
these refractory bricks are extremely
lightweight and full of air bubbles
which is why they're so great insulating
heat but it also means we won't need any
fancy tools to cut them a simple wood
saw is all you need because the bricks
are so soft
in reality you could probably carve them
out with kitchen utensils if you really
needed to I put a couple of bricks under
the edges to help channel the dust and
prevent the blade from scratching the
table when it cut through okay the three
lines are cut and you can see they
separate the brick into four pieces
I designed it this way so that one fire
brick will make two furnaces effectively
cutting the cost in half as well let's
move on to carving out the reaction
chamber and giving the furnace some
special features I'm using a 3/8 inch
drill bit and a two inch Forstner bit I
got at my local hardware store the
Forstner bit makes it easy to target the
exact center of the brick and doesn't
take much of an effort to begin chewing
away at the refractory material drilling
too fast could rip the brick apart so
let's take it slow and steady until the
holes around two inches deep which
should leave a one-inch base of
insulation at the bottom clean out the
dust you'll see we've got a nice little
chamber for our reactions to take place
now let's turn the brick on its side and
use a 3/8 inch drill bit to burrow down
near the top when it penetrates into the
chamber keep going straight down into
the other side and when it pops out the
bottom
gently push the bit outward to break
through the wall exposing the holes
let's do the same thing with the front
end of the furnace except this time
we're not going to go through the other
side we'll need to modify this hole by
drilling inward at
a 45-degree angle until the tip of the
bit meets the bottom of the chamber if
we carefully work the bit upward until
it breaks loose and clean up the edges a
bit the bottom half of the furnace is
finished and looks awesome the holes on
the sides are for the electrode then
this last one has a dual purpose for
watching the reaction and pouring molten
metals now the two smaller pieces are
the lids for the furnace and should only
need a very small modification to 3/8
inch holes drilled one inch from the
ends and three-quarters of an inch from
the sides to form a place where we can
safely store the electrodes when they're
glowing orange and too hot to put
anywhere else
speaking of electrodes we're gonna need
carbon rods like these to strike the arc
because they're the only things that'll
handle the extreme temperatures I went
to a local Super Center and picked up a
2-pack of six volt Lantern batteries for
under five dollars these ones are the
heavy-duty kind and don't worry if
they're newer you is because completely
dead batteries will work just as well
now we need to crack open the container
and my tool of choice for doing that is
a pair of wire cutters if we break the
lid off the top and cut the two wires
holding it on we've got easy access to
the four battery cells inside go ahead
and snip the wires connecting the cells
together then pinch the caps in the
center and gently pry them upward with a
little bit of effort they should pop
right out of the casing and just like
that you've got a carbon electrode ready
to go but that's not all these batteries
have all kinds of fun things hiding
inside the casings on these cells are
made of zinc and they're packed with
manganese dioxide so use something like
a screwdriver to scrape around the
inside pulling all that crumbly gunk out
the manganese dioxide could be saved for
other experiments but in this project
we're just interested in the carbon rods
and the zinc casings and I'm really
excited because we just scavenged eight
of them now just for fun I wedged the
zinc battery casings in my bench vise
and started cranking to see if it would
make the casings a bit smaller
apparently you can crush them down so
that are really compact and that's great
because we need them small for an
experiment we're gonna try in just a
minute
the last thing we need to make for the
mini arc furnace is a pair of adjustable
stinger grips I made a trip to the
hardware store four to five foot lengths
of eight gauge stranded copper wire to
half-inch copper couplings number twenty
stainless steel hose clamps and two sets
of six inch locking pliers i modified
the pliers by removing the rubber handle
grips to expose the metal then stripped
the end of the cables to expose the
copper so they can be secured directly
to the pliers with the hose clamps
now if you put the copper couplings on
the other ends of the cables and Hammer
them flat or clamp them with a bench
vise they make little copper lugs you
can hook up to an arc welder for power
like this homemade version I put
together with microwave parts you might
remember that project where we Center
tap the two transformers so it could
power the arc furnace on 120 volts ac
however it works much better on 240
volts so let's just leave it as is now
since the electrode grips are adjustable
they can be set to byte perfectly on to
any size carbon rod we need and hold
them firmly in place but there is
something you need to know about these
scavenge rods before you use them the
first time they make electrical contact
are gonna catch on fire there's some
kind of wax in the rods that burst into
flames as soon as they touch and it'll
take anywhere from 20 to 30 seconds to
burn it all out it generates a lot of
heat and a lot of smoke so try to do it
outside and away from anything flammable
at this point our mini arc furnace is
completely ready for operations so let's
test it out with the zinc battery
casings we scavenged earlier with one
casing in the chamber let's go ahead and
set the lid in place then power up the
arc welder so the electrodes are charged
and ready for action
the magic happens when the rods are
pushed through the holes on the sides
and suddenly bump into each other
striking a dangerous and blindingly hot
arc of electricity in less than 10
seconds you can see the rods are already
blazing hot and amazingly the metal is
already liquefied eight casings later
the chamber is full of liquefied zinc so
now that it's runny let's test out the
functionality of our built-in pour spout
this is how easy it is to transfer
molten metal from the mini arc furnace
into makeshift ingot moulds now zinc has
a relatively low melting point but this
furnace is resilient enough to tackle
high temperature metals like copper and
even steel as well so if you're in the
mood to see glowing streams of molten
copper or sparks flying around the room
look for those extreme experiments in
another project video all right are zinc
muffin is hardened so let's knock it out
of the muffin tray with a screwdriver
then dip it into a bowl of water to
quickly cool it the rest of the way the
result is a beautiful chunk of solid
zinc to add to our homemade metal
collection as a word of caution if you
breathe in any of the zinc oxide fumes
when melting zinc there's a small chance
of catching metal fume fever so if
you're recycling zinc yourself be sure
to wear a respirator or do your
experiments outside to reduce the risk
well now you know how to extract carbon
electrodes from old flashlight batteries
and carve insulating fire bricks into
custom arc reaction chambers by the way
if you cut the brick into 3 inch blocks
you'll get 3 furnaces and you can even
modify them to hold graphite crucibles
for smaller experiments well that's it
for now if you like this project perhaps
you'll like some why others check them
out at the king of random calm hey guys
thanks for watching this has been one of
my favorite projects so far and I'd love
to hear whether you liked it as well so
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