My burners, starting from the business end, are a 1"x 1 1/2" female reducer
on the end of a 12" piece of 1 1/2" galvanized pipe. Then a Tee, 6" more
inches of pipe and a floor flange that the blower mounts to. The reducer
on the front end has four 1/8" holes drilled around the shoulder for a
little gas/air mix to leak out and make small stabilizing flames around the
main opening. A piece of 2" conduit slips over it to shield the little
flames. The side port of the Tee is bushed down to 1/4" with the threads
drilled out so a 1/4" nipple can be pushed through until the inside end is
just shy of the middle of the main pipe. It needs to be a pretty tight fit
so put a pipe cap on the end to protect the threads and hammer it in. The
gas hose fits to the other end.
I drove a couple of pipes into the ground at the drain end of the tub and
mounted the burners on them with a block of wood and U-bolts.
I already had the blowers salvaged from the solar wood kiln. They came
from Grainger
http://www.grainger.com/Grainger/wwg...mId=1611663777
They put out 60CFM but I ran them with the intake about half covered. You
have to adjust the propane regulator and the blower intake so the flame is a
loud steady roar. If the flame pulses or blows out you have to much air.
If it turns yellow you have to much gas for the air. Start with a clean
blue flame and gradually increase the gas until the flame gets a yellow edge
then open the air a little and slowly increase the gas until you see the
yellow again. Keep doing that until the flame starts pulsing and then turn
everything down a notch until it stabilizes.
Now start slowly closing up the vents on the other end of the tub until you
feel hot air coming back out around the burners and then open them up
slightly. Check the flame again and adjust so there is no yellow. Now you
have the burners working at their maximum output and only enough air needed
for combustion entering he firebox.
You might get by with a single burner but I melted 4,000 pounds in a little
over 90 minutes using two. I also had a couple of sheets of mineral fiber
cloth salvaged from a closed neon sign shop that I covered the tub with to
try and keep the heat in. It seems to have helped a little. You can also
use it to cover any openings in the sides to help control air flow. You
might be able to bum some used cloth from a neon shop. They use it to
sketch out tube designs and form the tubes on it. Once it gets to scorched
up they throw it out.
One more trick. Cut a fresh straight green stick about 1" thick off of a
nearby bush. Crape Myrtle is ideal. Strip the branches and leaves but
leave the bark. When the melt is about ready, stir it with the stick and
the stick will start to "sing". As the moisture in the wood boils out in
little microburst it sets up ultrasonic vibrations in the molten lead and
the dross will magically rise to the top so you can skim it off.
Needless to say the mold must be ABSOLUTELY DRY and ALWAYS remember, pilot
fire first, then blower and finally gas.
--
Glenn Ashmore
I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at:
http://www.rutuonline.com
Shameless Commercial Division:
http://www.spade-anchor-us.com
"Hess cutter 56" wrote in message
ups.com...
I like the Idea of using Propane Burners! There are some good examples
on The Backyard meatelcastimg web site. Glenn how much air { CFM]
do you think you where moving through the Burners? And what size
orifice ? Can you give me a more detailed deception of the Burner set
up? Thank You CW