For this project I’m going to show you how to make a Hot Wire Styro-Slicer that cuts
styrofoam shapes with precision and control. It’ll produce professional looking 3Ds props
for cosplay or metal casting, as well as make foam fighter jets, that actually fly across
the room. The Styro-Slicer has adjustable power settings, cuts at any angle you need,
and the best part is, the whole system fits together ergonomically, for easy and clutter-free storage.
Let’s start this project with a simple experiment, using a 6 volt lantern battery and a thin piece of hanger wire.
If we wrap the ends of the wire around the battery terminals, you can see it gets incredibly hot, in just an instant.
If fact it’s so hot, that if we try touching it to a small piece of styrofoam, it slices
right through, like a hot knife, on butter.
That’s the basic concept of how our hot wire foam cutter is going to work, so let’s
get started building the foam factory with some 3/4” PVC tubing and a few connectors.
These pieces will create the frame for our multi-functional wire saw, and you should
be able to find all of them easily, at any home improvement store, in the sprinkler isle.
Cut two pieces of tubing 11” long, and one other piece 12”.
And the only fittings you’re going to need are two 90º elbows, and two slip caps.
Now if you’re planning to customize the colors on your Styro-Slicer, go ahead and
paint the elbows and the slip caps now, because it will save you a step later on.
The next things we’ll be needing, are some #8 flat washers, and two #8 eye bolts, around 1-5/8” long.
Place one of the washers on the bolt, then screw them both firmly into the center of the cap.
I pre-drilled my hole, using a 5/32” drill bit, and it really couldn’t have worked better.
Now continue screwing the eye-bolt into the cap, until it’s tight against the outside
washer, then do the exact same thing with the other one.
The next step is to make a hole in the center of the12” pipe, so mark the tubing 6”
from the end, and begin drilling.
We only want a hole in one side though, so when the drill bit punches through the top, it’s time to stop.
I drilled my hole 3/8” wide, but you can really make yours any size you want, as long
as you can get an electric cord to fit through it.
And speaking of cords, we’re going to need one of those, next.
All we’re really after here is the cord itself, so go ahead and chop off whatever’s
on the ends, then separate the two wires by carefully pulling them apart.
I split my cord into strands about 2 feet long, which is actually a bit more than we
need, but it gives us a little wiggle room for when we attach it in just a second.
Next we’ll need to expose the bare copper wire inside, so use wire strippers to remove
about an inch of the plastic coating from the ends.
Then twist the strands tightly together, and bend it over, so you can twist it together
at the bottom, and form a little metal loop.
Carefully push the split wires through the hole in the tubing, and continue working them
in, until the wires snake around the corners, and pop out the other ends.
Now if you can figure out how to tie a knot on the inside, the cable won’t be able to
pull back out accidentally, and it’ll prevent the wires from splitting down any further.
So tie it off if you can figure out how to do it. Otherwise, don’t worry too much about it.
All that’s left to do now, is push the individual wires through the two remaining tubes, and
secure them to the end caps.
Add a washer to the bolt inside the cap, then slip the wire loop over the end of the bolt
and push it down to the bottom.
Add one more washer and a hex nut, then use something like a pair of needle nose pliers
to help tighten the whole assembly together.
Now simply push the end caps on the tubes as tightly as you can, and just like that,
the frame for your wire saw is finished.
You could use it just like this, but if you want to kick it up a notch, trying using a
bit of Duck Tape to add a splash of color.
The only thing our hot wire foam cutter needs now, is the hot wire. And for that I’ll
be using a 1-1/2” extension spring, and some stainless steel hanger wire, which you’ll
find, in the hardware isle.
I got a 9 ft roll for a little under $4, which is way more than I’ll ever need, and should last forever.
Measure the wire so it’s a couple inches longer than the frame, then go ahead and snip
it to size, and now here’s the cool part.
If you look closely, you’ll notice the hanger wire is made of 7 smaller wires twisted together.
So if we unravel them, we end up with 7, super thin, stainless steel cutting wires. And plenty
more where they came from.
At this point, go ahead and get the 1-1/2” extension spring ready, by connecting it to
one of the eye-bolts. The easiest way to connect it is by pulling the hook open with a pair
of pliers, then looping it inside the bolt and letting go.
Fasten one end of the steel wire, to the bottom eye-bolt by folding the wire back over itself
and twisting it around a few times.
Now loop the other end through the bottom of the spring. But before you twist it off,
pull the wire firmly, and stretch it out first.
This will “spring-load” the wire with tension, which is really important for keeping
it tight, when it expands and contracts rapidly.
With that final step, the wire cutter’s done. Except you might have noticed, the wire’s still a bit wavy.
Simply take a screw, or the handle of a spoon, and slide it back and forth a few times to
make the ripples disappear.
Now let’s do a quick and simple test to make sure everything got connected properly,
by touching the ends of the wires, to the terminals of the lantern battery.
If you did it right and your connections are solid, the wire will heat up and slice through
styrofoam, without any trouble at all.
Ok now that we’ve got a wire cutting blade, let’s go ahead and build the foam cutting
factory I designed to go with it.
The first thing you’re going to need is 1/2” medium density fiberboard (MDF) cut 18” square.
We’ll also need an 8 foot 2x4”, which you can get for about $2.
I’m using a chop-saw to make quick and clean cuts, but you can use whatever tools work best for you.
But in any case, you’ll need to cut the first piece 18” long. Then a 15” piece
for the side. Another 15” piece for the bottom. Followed by an 11-1/2” piece for the other side.
A 5” block fills the gap above that. Followed by a 3-1/2” block on the bottom left. Then
another 3-1/2” block that’ll go inside, on the bottom right, a little later on.
Now that our 2x4” is cut, mark a 10” line down the center of the MDF square, and use
something like a chop saw to follow the line from the center marking, right out the side.
You’ll see what this groove is for a little later.
Alright, it’s time to secure the blocks together, and for that I’m using eight,
3” wood screws, and an 1/8” drill bit.
Start by lining all the blocks in position, on the bottom of the board, then use the 1/8”
bit to drill pilot holes in the wood. This way, the wood won’t crack when you screw it together.
The blocks go together in 3 different segments, and you should be able to figure out how to
attach them, by studying how I did mine.
Before we go any further, let’s stop, and hack a square hole out of the 15” sidewall,
to accommodate the dimmer switch we’ll be adding in just a minute.
I used a 3/8” bit to drill holes in the corners, then connected the dots with a jig
saw, to cut the sides, and pop the block out.
If you did it right, your hole will be on the left side of the base, when the 18” board is facing forward.
Ok let’s move onto securing the work-surface next.
We’ll need to drill pilot holes through the MDF like we did for the base frame, and
it’s a good idea to invest in a countersink bit, so you can get the heads of the screws to drop below the surface.
I used ten, 1-1/2” wood screws to hold the board to the 2x4’s, and two, 3” wood screws
in the upper right area, to secure the 3-1/2” reinforcing block, to the underside of the table.
These are the measurements I used, and it’s important you take time to measure and fasten
yours the same way, because it’s all part of a master plan, that will come together later on.
Now just for fun, I thought it would be a good idea to use my flush-mount router station
to quickly clean up the edges a bit, by rounding them out.
For just a little extra effort, you can see what an amazing difference it makes. And all
I used was a 1/2” rounding bit.
If you want to see how I made this router station, look for how to build it, in another project video.
Alright, let’s make sure all the wood pieces fit together snugly, on the underside, then
double-check the base support assembly didn’t get screwed on. That’s important.
We still have one thing left to do with the base support, and that’s to drill a 3/8”
hole directly in the center, and 5” from the bottom. That’s it. At this point the workstation is finished.
Now just for looks, I decided to spray-paint mine black, so it would match my wire saw
better, but however you color yours, is completely up to you.
The next step in assembling our foam cutting factory is attaching the arm assembly, to the support base.
Stand the saw upright so it looks like the letter “C”, and center it in the middleof the board.
Now if you push a pen through the hole in the back, and mark the tubing, you can use
your 3/8” drill bit to carefully cut a matching hole right through the tube.
Make sure you don’t cut the wires inside, and put something like a scrap piece of wood
underneath, so you don’t scratch up your table when the drill finally punches through.
Let’s fasten the two parts together next, using a 3/8” x 3-1/2” hex bolt. Two 5/16”
cut washers/ A 3/8” wing nut/ And two 5/16” tank bolt washers, which you’ll find in the plumbing section.
The bolt, and one washer, go on the forward side of the tubing, while the two tank go on the back.washers
And after inserting the bolt all the way through the hole in the support stand, add one more
washer and a wing nut, to clamp the system together.
The wing nut simply needs to be screwed on hand-tight, and with that final addition,
you’ve just completed a stand-alone cutting assembly, that looks awesome, and has a of really cool features. lot
The cutting arm is designed to pivot on the bolt, so you can adjust the angle of the blade
anyway you need it, and even 180 degrees the other way.
If that’s not enough, you can release the wing-nut and slide the whole assembly out,
to cut larger blocks free-handed.
Now to bring our Styro-Slicer to life we just need a way to safely electrify it, and control
the power, so let’s finish up, with the electrical system, next.
I went to the hardware store and got a 600 watt dimmer switch, that you can turn on or off just by pushing it.
We’re also going to need a 12 volt power transformer, a 10 amp fuse and another 6’ length of cord.
Now if you have trouble finding a transformer, or simply don’t want to shell out for one,
you’ll probably be able to salvage one for free, by hacking open an old stereo and pulling
one off the power supply. That’s what I did for my first prototype, and it works just as well.
The dimmer switch goes in position from the outside, and gets secured in place, with two 1” wood screws.
You’ll need a cover plate as well to make it look nice, and when that’s screwed on,
replace the knob, then flip the whole workstation over.
I decided to install my transformer about halfway down the side, and used two more 1”
screws to secure it as tightly against the top, as I could get it.
And it helps if you position the side with the 3 wires, facing down.
The 10 amp fuse isn’t really necessary, but it’s good practice to have in place
just in-case of a short, so make sure it’s actually got a fuse inside, then go ahead
and connect everything together, using the small wire nuts that came with the dimmer switch.
Now to save time, I went ahead and just wired everything together. And after you do the
same, it should look something like this.
You can see the main power cord comes in from the outlet and connects to the 10 amp fuse
first, which then connects to the black wire on the dimmer switch next.
The red wire coming out of the dimmer switch connects to the black cord on the primary
side of the transformer, and the other black cord connects to the wire running back to the outlet.
Now on the secondary side of the transformer, you might have noticed two yellow wires and one black one.
The two yellow wires supply 12 volts, and the black wire is center-tapped for half power.
This means that connecting them to a 3 position switch will give us the option to cycle the
system between 0 volts, 6 volts and 12 volts, on demand.
Now it doesn’t really matter which yellow wire you connect to the switch, as long as
it’s soldered to one side, with the black wire soldered to the other.
The remaining yellow wire needs to be connected to the cord running to the hot wire assembly.
And the return wire, connects back to the middle, of the 3 position switch.
It sounds complicated, but it’s really not that bad once you get into it.
Now the two power cords are designed to feed out the back, so they don’t get in the way.
One cord is for the supply power, that gets plugged into any regular power outlet. And
the other cord, runs the regulated power to the cutter assembly.
At this point, the Styro-Slicer is done, and ready to use as soon as you are.
Simply push the cutting arm into place, with the wire in the center of the work surface,
then flip the red switch to the 6 volt setting, which I call “normal power”.
Push the dimmer switch on, then gently crank up the power, and you’re in business.
If everything’s working the way it should, your wire will instantly heat up, and you
can start slicing through styrofoam right away. Making some of the smoothest, and cleanest cuts, you can imagine.
For one final touch, I added a couple 1” screws to the inside of the base, so we can
store the rest of the hanger wire, then secured a latch on the upper side of the support stand,
so the whole system locks together, for quick and easy storage.
By the way, there’s also a backup battery cable in there, that will connect the system
to solar, or battery power, which makes the whole system portable, and off the grid.
Well now you know how to rise up, and become a master styrofoam maker, by building yourself
a homemade Styro-Slicer.
That gives you precision control for cutting custom props like a Mini Master Sword. Or
slicing out something more intricate, like a squadron of 3D fighter jets. Look for how to make these in another video.
Well that’s it for now. If you liked this project, perhaps you’ll like some of my others.
Check them out at www.thekingofrandom.com