Propane Burner for Foundry Furnace

Project:
This goes with the main blog about my foundry furnace (http://chris-eigenheer.blogspot.com/2012/02/home-foundry.html). I had to build a propane burner from scratch to make it work with the furnace and for it to put out enough BTUs. 

Process:
After taking my 4 year old boy out to McDonalds for some breakfast, I decided I was gonna take him out in the shop and teach him some metal working skills and how to play with fire. Ok, I was just told by my wife that I wasn't supposed to have him out there when I blow up stuff, I mean build propane burners!

The propane burner I bought at Harbor Freight was a piece of crap and suitable just about only to burn weeds so I needed something a little more sophisticated. After some research I found out that a venturi effect would be perfected with a 30 degree intake nozzle angle and a 5 degree exit nozzle angle, but since I don't have a metal lathe (yet!) I ended up taking a 12" piece of 1" black water pipe that I got for free at a local sprinkler business, screwed on a 1-1/2" to 1" reducer at one end and a 2" to 1" reducer at the intake (those cost me $10 bucks cash at the same sprinkler place).

For the propane intake, I found some 3/16" brake line pipe from one of my previous car fixing adventure, a male bubble-flare adapter and a female to female adapter to hook it up to the propane torch from Harbor Freight (without the propane torch burner).

I had to make a bubble-flare on the brake line first, then turn it into a double flare and connect the brake line to the f-to-f fitting with the male adapter. Then I drilled a hole through the 1" black pipe, drilled a 1/16" hole into the brake line and stuck the brake line through the 1" water pipe at a right angle.

Once it was stuck through, I flattened the open end and soldered it shut with some regular solder. Works like a charm

Connecting the brake line to the propane torch needed a bit of grinding and re-tapping the threads to make them fit the f-to-f adapter but after some time that worked. The video below was taken before I welded the set screws to stabilize the brake line.

Once I connected the propane tank I realized that the brake line turned inside the water pipe and created a less than ideal burn ratio so I had to weld a nipple to the 1" pipe, weld 3 nuts to the nipple and use 3 screws to fasten the brake line solid. After welding a mounting bracket to the furnace and grinding off the hot end of the burner (it was just about 1/8" too large) I was able to stick it through the side of the furnace, fasten it in place with the set screw and light 'er up.

Then, at 8:30PM I decided to give the whole melting metal a whirl. Fired it up and within 10 minutes the crucible was red hot. I threw some pieces of a smashed up tranny case in there and within notime i had 10 lbs of molten aluminum. I made a quick sand mold out of some yoghurt cans, scooped off the dross at the top of the aluminum and poured it into the mod. Le voila! It works. Now I can build me a wood model of some ingots and start melting/refining the aluminum. Good times! 

Pictures:

 

The burner in action

 

The first aluminum melt

Original burner used to dry out refractory cement wasn't powerful enough

The double flaring tool used to first create a bubble flare on the 3/16" brake line

Then the same tool was used to create a double flare

Here's the finished brake line with the double flare, the male adapter and the f-to-f adapter

The double flaring tool. $20 bucks at Princess Auto

The burner in action. Note the shadows that the heat waves cast on the door...spectacular

View from the rear to the front while the burner was burning

The nipple with the 3 set screws to hold the position of the brake line in the perfect place

The real burner in the furnace

Close-up of the bracket I welded to the furnace to hold the burner in place and to make for easy removal of the burner

The red-hot glowing crucible with the molten aluminum

The yellow at the top is the front nozzle of the propane burner a "little" warm

The top of the sand mold once the aluminum solidified

The bottom of the sand mold where the molten aluminum contacted the second mold frame

It looks like there was a metal bold on one of the aluminum pieces I melted up. It just sank to the bottom and I could scoop it up once it all cooled down

From top, counter-clockwise: 10lb ingots, dross, left-over stuff from the bottom of the crucible

Tools:
Angle grinder, bench grinder, drill press, mig welder, double flaring tool, pipe thread cutter 

Materials:
12" of 1" diameter schedule 40 black water pipe, one 1-1/2" to 1" reducer, one 2" to 1" reducer, 6" of 3/16" brake line, one male double flare adapter, one female-to-female double flare adapter, propane torch, set screws, 4" of 1"x1/4" flat iron, some gas-rated teflon tape, 2" of 3/4" water pipe, some nuts for the set screws 

Cost:
$10 for the reducers, $10 for the propane torch, the rest was left-over pieces of stuff I had in the shop. 

Time:
About 7 hours including hunting for parts at Princess Auto and Tri-Province 

Conclusion:
She's roaring alright! Gonna make me some molten aluminum now!