wanted a small
portable gas forge that I could use for small forging jobs that did not
require the use of a large forge. When I first started building
I wanted to make it run using a hand held propane torch, but I could
get a good heat using the propane. So I tried using Mapp gas, and
I was able to heat the test piece to 1950 degrees. I used Tempil sticks
to verify the temperature of the test piece.
I tried several
outfits and settled on using a Bernz O Matic model # JTH7. It
produce the best heat and has the added flexibility of the separate
wand. This picture is of the torch wand removed from the forge. I
got the torch outfit at Home Depot for less than $30.00.
The forge body is a
6" schedule 10 pipe 8" long. I welded a plate on the backside of the
to close it off. The pipe in the side of the forge body that
the torch wand is 3/4" pipe that has a hole tapped in the top for a
screw. The forge liner is 1" 8# Fiberfrax ceramic blanket.
Update: April 12, 2005Doug
Marx recently sent me a picture of his new mini forge along with a
description of how he built it. He built the forge using the basic mini
forge design from this web page, he used a 6" weld cap, 6" x 4" weld
pipe reducer, and a short piece of six inch pipe. This is a great
looking little forge.
November 15, 2008: Bernz O Matic is
phasing out the model # JTH7 torch set and replacing it with the BZ
8250 Trigger-Start Hose Torch. This torch outfit features a 5ft.
hose, instant on/off trigger ignite and a Stainless Steel burner
tube. The Stainless steel burner tube is a great improvement over
the old burner tube made out of brass because I melted one while I was
not paying attention to the mini forge that was running out of
gas. I bought one of the torch sets today and the price was $
64.00 for the set, that is a lot more than I paid for the JTH7 set but
that it is well worth it for the updated features. Bernzomatic is
also discontinuing the Mapp gas bottles and replacing it with Propylene
gas bottles. The Mapp gas open air flame was 3750º F and the Propylene
open air flame is 3730º
there is not
much difference in temperature output. The old 14.1 ounce tall
bottles are also being replaced with a shorter and fatter bottle that
holds 16.92 ounces per bottle; these bottles are called Fat Boys.
November 28, 2008: Today I
installed the BZ 8250 torch outfit with Propylene
gas in a coffee can forge and the forge
temperature after 15 minutes was 2050 º F .
The picture above is of the BZ
Update: January 28, 2013:
Sometime in 2008 Mapp gas was discontinued and was replaced with Mapp
Pro gas, the advertised open air flame
temperature of Mapp gas was 3750 degrees Fahrenheit and the advertised
open air flame temperature of Mapp Pro is 3730 degrees
Fahrenheit. The open air flame
temperature for Propane gas is 3600 degrees Fahrenheit so is the extra
130 degrees that the Mapp Pro puts out worth the extra money you have
to pay for the Mapp Pro gas. While doing research on this subject
there seams to be a lot of different open air flame temperatures listed
of the gases that I have talked about, the ones that I used here seam
be the most consistent that I found.