In this video I’m going to show you how to build a fire breathing “Gas Blaster”
torch from simple, and common materials. This homemade jet torch shoots a steady, and adjustable
flame, that gets hot enough to melt metal. Which means, now you can dodge the challenges
of charcoal, by powering your foundry, on propane.
To start this project, simply stop in to see any local propane supplier, and pick up an 8’ length of propane hose.
You’ll need 1/4” hose with two 3/8” flare fittings crimped to the ends, which
they’ll probably make for you right there at the shop.
And while you’re at it, see if they have a 1/4” brass plug, and a 3/8” flare x 1/4” 45º fitting they can sell you as well.
The other parts are a 1/4” ball valve. A 1/4” pipe nipple, and a 1/4” galvanized
coupling. All available, at your local hardware store.
Alright let’s get started wrapping each of the threaded ends with teflon tape, so
they’ll make a better seal when we screw them together in just a minute.
This is pretty much the order the pieces are going together, so let’s kick off the assembly
by attaching the flared end of the brass 45º, to the end of the 8’ hose.
Screw the fittings together finger tight, then use a pair of pliers to sinch them together,
so they make an air-tight seal.
Add the ball valve next, screwing it tightly together the same way, then screw the pipe nipple onto the end.
It’s important that the valve handle opens toward you, and shuts off in the down position.
So double-check you put it on the right way, then move on to making the intake nozzle next.
Now rather than screwing the 1/4” coupling to the pipe nipple right now, it’s going
to be really helpful to use a sanding belt, or a metal file, to flatten down each of the four sides first.
The flattened sides will make it easier for 4 set screws to bite into place later on,
and hold the coupling securely in place.
Alright, let’s move on to assembling the propane nozzle, and for that we’ll need
the brass plug from earlier, a 6mm tap, and a “wire feed” welding tip.
Now you could save money, simply by drilling a 0.6mm hole directly into the brass plug
itself, but I’m using “wire feed” contact tips because they’re replaceable, they look
cool, and the hole's exactly the right size for this torch.
Go ahead and drill a 3/16” hole directly through the center of the brass plug.
It’s important to get the hole as straight as you can, so I’m using a drill press I
found at a garage sale for $20.
But if you’ve got steady hands, you can make it work just fine with a cordless-drill as well.
The next step is to cut inner threads in the hole, so the welding tip will screw into place.
And an M6 x 1.0 tool, works great for tapping that.
I added thread tape to the welding tip just for good measure, and with a few flicks of
the fingers, you can see we’ve got a good looking propane nozzle, ready to join the system.
Go ahead and screw the nozzle securely to the steel coupling, then just set it to the
side for a second, because we’re actually going to move over, to working on the jet tube for a bit.
The components we’ll need to finish the torch, are four socket cap screws (M5 - 0.8 x 25mm),
a 1” steel reducer coupling (1” x 3/4”), a 1-1/2” steel reducer coupling (1-1/2” x 3/4”), and a 6” steel pipe (3/4” x 6”).
Now to secure the jet assembly, to the nozzle we first have to drill holes for the set screws.
So file down the four sides of the larger coupling to make them nice and flat, then
clamp it in a vice to hold it securely. Because it’s important these holes are drilled as straight as possible.
Another cool trick is to screw the pipe on and adjust it horizontally, to help ensure
the coupling is about as perpendicular as you can get it.
Now the position of the holes you drill, is really important.
You need two 1/8” holes drilled through the rim of the large end, opposite from each other.
Then two more 1/8” holes perpendicular to the first two, and right on the edge, where
the adaptor begins sloping down.
We need to tap these holes as well, but they’re a slightly different size, so let’s use
an M5 x 0.8 tap this time, because that’s the one that matches the threads on our cap screws.
Ok, now that we’ve got the intake port machined and completed, the hardest part is over, and
we can bring back the nozzle we made earlier, and secure the two pieces together with set screws.
Twist the cap screws into the holes, and you should find they easily go all the way in, by hand.
And if you drilled and tapped your holes correctly, the four tips of the screws will meet together, and form a cross at the center.
Let’s combine these two parts together, simply by setting the adaptor overtop of the
nozzle, and checking to make sure the tip is centered inside the hole at the top.
Let’s secure it in position by hand-tightening the screws until we feel them touch the
coupling inside, then simply fine-tune the adjustments, keeping the nozzle as centered as possible.
Now when the screws are in "finger tight", we can make the assembly a little stronger, by
adding a some tension, with a screw driver.
The screws should only need about 1/4 twist each, to lock the nozzle on tight. But feel
free to go around a second time, if you want to be extra sure.
At this point our modified intake adaptor has two set-screws at the bottom, two perpendicular
screws an inch above those, and a propane nozzle, sitting perfectly centered, in the middle.
Now it’s a really good idea to have an adjustable regulator, to control the air flowing through
the torch. So let’s make one of those next.
All you’ll need is an empty can of tuna, and this air-regulator template I made, which
you can have for free. Just look in the description for a link on where to get it.
Print, and cut out one of the paper templates, then glue it directly to the center of the steel lid.
The steel should be thin enough to slice with a pair of scissors, so carefully cut around
the edges of the template, then gently mold it from the back, into a bowl-shape.
With the center pressed in and the edges raised up a bit, it should look a bit like a small steel shield.
This slit on the side let’s you slip the regulator completely over the intake port,
essentially blocking off any air-flow. And you’ll see why that’s important in a minute.
From this point, the rest of the torch is really easy to assemble.
Simply drop two, 1/2” cut washers over the end of the pipe nipple, then grab the intake
adaptor and screw the inside coupling on as tightly as you can get it by hand.
Now screw the small steel adaptor onto the 6” pipe until it’s hand tight as well,
then loosely screw those pieces, onto the air-intake adaptor.
Just like that, this “Gas Blaster” torch is completely finished, and ready to breathe fire.
Now, you could hook this up to your propane tank and use it right away, but for safety
and protection, you really should add a pressure gauge, and some kind of regulator valve.
You’ll also need a 1/4” Prest-O-Lite (POL) valve, for connecting the regulator to the
propane tank, and a 1/4” x 3/8” flare fitting, for connecting the regulator, to the hose.
Now open the valve on the tank, and spin the regulator up to about 30 PSI, so you can check
for any leaks in the hose, and the connections.
If you hear any hissing, then double-check the connections have thread-tape on them,
and tighten everything up, until the hissing stops.
At this point, our propane torch is 100% finished, so why not take it for a test drive, and see what it can do?
Now firing up the torch, really couldn’t be easier. Simply hold a flame near the nozzle
with one hand, and slowly open the valve on the torch, with the other.
It should light off no problem, and watch this. If we slowly adjust the air-regulator
at the back, we can convert it from a fire belching blow torch, to a metal melting jet-torch in just an instant.
The sound, and the color of the flame, will tell you a lot, about how the fuel, and the air are balanced.
So if you’re planning to melt metal, just play with the flame until you get a nice blue color, and a jet-loud roar.
Blue flames like this are slightly oxidizing, and are the color I use, for my backyard casting.
By regulating the air-intake, you have the option of using any length of pipe you want,
and can slide between an oxidizing flame, (Oxygen > Gas) and a reducing flame, (Gas > Oxygen) as quick as you need.
When you’re ready to shut it off, simply close the valve on the handle, and the flame disappears in an instant.
Perhaps the best part about this jet-torch design, is that it works with the "flower pot
foundry", I showed you how to make in a previous project, without any other modifications required.
The end flare doesn’t actually fit through blower port though, but you can just take it off.
Amazingly, the inside of the foundry acts as an improvised nozzle all by itself, so
just point the tube into the hole, and it’ll work just fine.
That’s really all it takes to convert your backyard foundry, to propane.
Add a little gas and light it off with a bbq igniter, then adjust the air-flow until you
see the flame tighten into a fiery vortex, of metal melting power.
Now this set-up can get really hot in a hurry, so quickly put on the lid, and stand back.
In as little as 5 minutes, the inside of your foundry will be glowing red-hot, and you’ll
be melting all your favorite metals, without any of the challenges you had, with charcoal.
There’s no babysitting, no mess to clean up afterward, and what’s really cool, is
you’ll probably be saving money as well.
The “Gas Blaster” is designed to self regulate, and sustain a healthy flame from
1 PSI, all the way through 55 PSI, without even flinching.
That means you can run your foundry as hot, or as cool as you want, just by regulating
the pressure from the propane tank.
The inside of the foundry gets hot enough to boil brass, and liquefy bullet casings
on contact, but amazingly, the intake end of the torch stays relatively cool the entire time.
By the way, if one jet-torch can do all that, why not exponentialize the power, by adding another?
I added a “T” fitting to my hose so I could split it, and run separate lines to each torch.
Then drilled a second hole through the side of my foundry, so now the flames hit the crucible, from either side.
Try it for yourself, and you’ll be amazed at how fast this flaming duo, can really heat things up.
Well now you know how to use easily accessible, and easy to replace parts, to make a “Gas
Blaster” jet torch, and convert your backyard foundry, to propane.
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