Several years ago somebody sent
me pictures of a forge that they built using a portable air
tank for the forge body. I thought that this was a
great idea at the time, but when I got to shopping around
for a new air tank back then the prices were around $60.00
which seemed high. I came across a 5 Gallon Air Tank
at Tractor Supply the other day for $24.99. So now
that the price of them has come down, I decided that I would
do a tutorial for building one. The item number of the
air tank at Tractor Supply is
SKU #122581799. The some nice things about this tank
are it already has a leg welded on it and it is light
weight. I have looked at stores and online and Tractor
Supply is the cheapest price on the air tank that I have
found. This forge was built using two inches of 1"
thick Superwool HT lining which will give you a forge that
is 5 inches in diameter and 12 inches long inside.
This gives you 236 cubic inches of forge interior.
I know that there are 7, 10, and 11 gallon air tanks out
there for sale as well. You could use the same build
methods for these size tanks with two or three
burners. Just make sure that you use the following
rules in the build. No more than 350 cubic inches of
interior space for each 3/4 inch burner and you need to have
your burners 3.5" to 4" center to center so you will not
have uneven heating of your metal.
The air tank out of the box
I got the air fittings removed from the tank I used
some WD-40 and a scraper to remove all of the
decals. Let the WD-40 soak in a little bit and
the decals will come right off with the scraper.
used a 4 1/2" right angle grinder with a 1/16" cut-off
wheel to cut the front of the air tank off.
You will need to make a hole in the
forge body for the burner holder by using a 2" hole saw in a
cordless drill. Be careful when drilling the hole,
because you are not drilling a flat surface and the hole saw
will want to grab when it starts to come through the steel.
time I am using a Cast Iron pipe bushing for a port
opening in the rear of the forge. You can use
either a 2" x 2 1/2" Cast Iron Pipe bushing and
(1) 2 1/2" conduit lock ring or 2 1/2" x 3" cast iron
pipe bushing and (1) 3" conduit lock ring.
For this build I am going with the 2" x 2 1/2" Cast
Iron Pipe bushing and (1) 2 1/2" conduit lock ring
this will give you a 2" opening in the back of the
forge. I used a 3" hole saw to drill the opening
in the air tank. If you decide to go with the 2
1/2" x 3" cast iron pipe bushing and (1) 3" conduit
lock ring this will give you a 2 1/2" opening in the
back. You can always put a piece a scrap
Superwool in the port when not in use. I am not
sure of the longevity of the cast iron fittings but
there are several commercially built forges on the
market that use them so I figured that I would give
them a try.
The pictures above show the Superwool cut
for the back end of the forge and the forge lined with two
layers of 1" Superwool installed.
The firebricks were cut to a size of
3.5" x 6" using a 4.5" angle grinder with a cut off
wheel. This is a picture of the forge with the
firebricks installed and the Superwool coated with Plistix
900F coating. I let the forge sit for 24 hours after
coating it with the Plistix 900F and then I slowly cured it
using a Propane torch.
I used scrap Superwool to close up
the opening around the burner tube and the burner
holder. This will help protect the burner and stops
all of the heat from escaping around it.
Here is the forge burning at 8 PSI
and using two bricks for the front of the forge.
The pictures above show a couple of
different options that you can use for the front of the
forge opening using the 2 1/2" x 9" x 4 1/2"
soft firebricks in different configurations.
Build Note: I had
to weld a 1/16 inch shim to the bottom of the backside of
the forge so the front of the forge would be level and
square with the firebricks that I am using to help close off
the front. I am not sure if all air tanks are like
this or not.
Forge Parts List:
gallon air tank (Tractor Supply SKU #122581799
1/4-20 x 3/4" NC hex head caps screws ( 3 for the
burner holder ) (3) 1/4"
lock nuts (1) 1
1/2" x 4" schedule 40 black pipe nipple (2) 1
1/2" conduit lock rings ( 4
running feet) 1" 8# density 2372°F Superwool HT 24"
wide (1) 3/4"
Side arm burner or (1) Z Burner (2) 9" x
4 1/2" x 1/2" 3000°F
heavy duty fire bricks ( for the forge floor ) Cut to 6" x
3.5" size (5) 2 1/2" x 9"
x 4 1/2" 2300°F insulated firebricks( to make the front of the forge) (2
Pounds) Plistix 900F (1) 2" x
2 1/2" Cast Iron Pipe bushing and (1) 2 1/2" conduit lock
ring or 2 1/2" x 3" cast iron pipe bushing and (1) 3"
conduit lock ring. (to make the rear port opening )
a list of parts
that you will need to get from the propane tank to the
burner gas inlet. (Note: all of the following parts listed
below are contained in the single burner connection kit. )
MPT x full flow Hard Nose POL 7/8 hex (1) 1/4"
X 1/4" FPT 3-35 lb Propane Regulator (1) 0 -
30 PSI Gauge bottom connect with 1/4" mpt (1)
propane hose with 1/4" male pipe threads on both ends (1) 1/4"
N.P.T. ball valve (1) 1/4"
x 1/8" threaded black iron pipe bushing
Disclaimer Notice: Zoeller
Forge specifically disclaim any responsibility or liability
for damages or injuries as a result of any construction,
design, use or application of information contained on this