Introduction: Foundry: How to Build a Burner (Natural Gas)

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I'm fairly new to the whole casting bit, just got my foundry up and running a month ago. It took me about six months to figure out how to build a natural gas burner, do to the lack of instruction on the web, so I figured I'd throw in my two cents and show how I made mine.

What I'm posting is what I've learned through trial and error. If anyone has more information or ideas I'd appreciate it if you would let me know.

That being said, I'm not responsible for the actions or ideas of anyone that reads this. There is always a risk when working on "diy" projects, especially those that involve fire. Please practice safety when engaging in any type of casting or metal work.

Step 1: Background

Just a bit of background to explain why I made the burner the way I did.

First off I'm a college student, (i.e. broke) I had to use what was readily available to me, so propane was out of the question.

The natural gas line that I had access to was only 5 psi @ 3/4", so I needed a forced air system.

I had bought the foundry (minus the burner) from a blacksmith shop I go to on the weekends, so the inlet diameter on mine was preset at 1.5" with a 1" hole going into the brick work. It's inside diameter is 10" with a 12" depth. The crucible I have is an A10 (7 5/16" inside height, 5 11/16" inside top, and 3 3/4" inside bottom; holds about 1.5 L)

Step 2: Materials

Materials:

Blower:
50-150 cfm (i used a Dayton 11TDR3 squirrel cage)

Pipes:
3/4" ball valve (for natural gas line-in)
3/4" nipple (flared/not flared, depends on your ball valve)
3/4"-1/2" reducer
1/2"x6" nipple (variable)
1/2" end cap
2"-1" bushing
1"-3/4" bushing
2' T-pipe
2"x10" nipple
2"x6" nipple (variable)
2" floor mount
2"-1 1/2" reducer
1 1/2"- 3/4' bushing
3/4"-18" pipe (I had to go back and add a coupling and 3/4"x4" nipple so go with 24")
1 1/2" -1" reducer
1 1/2"x5" nipple
plumbers tape or pipe dope (for sealing the pipes)

You will also need a drill, 1/8' drill bit, vice, welder, and an angle grinder; not to mention the skills and equipment to use them properly.

Step 3: Assembly: Gas Inlet

This is based off what I had to work with. Obviously, if you have a 1/2" natural gas outlet you don't need the 3/4" nipple or the reducer.

Pipes:
3/4" ball valve (for natural gas line-in)
3/4" nipple (flared/not flared, depends on your ball valve)
3/4"-1/2" reducer
1/2"x6" nipple (variable)
1/2" end cap
2"-1" bushing
1"-3/4" bushing

Assembly:
Measure the distance (on the inside) of the 2" T-pipe from one end to the opposing side of the "T" in the pipe. The goal is to get the 1/2" pipe with the end cap, have a final placement centered at that distance in the long portion of the T-pipe when the bushing and everything is screwed in.

Mark on the 1/2" pipe the distance needed. (I used a 6" pipe, but you could go longer if you want.)

If you can find a 2"-3/4" bushing use that, if you can't, do what I did and find its equivalent.

Clean and weld the 1/2" pipe (at the mark) to the 3/4" bushing that your going to use. Make sure its centered. use tact welds and a vice as needed.

Drill a 1/8" hole in the center of the 1/2" end cap and secure tightly on the end that is going into the T-pipe. use plumbers tape or dope

Use plumbers tape or dope on the other end of the 1/2" pipe and screw into the reducer, or 1/2" ball valve.

If using the reducer like I did attach to 3/4" nipple, then attach that to the ball valve. use plumbers tape or dope.

Secure the assembled part to the 2" T-pipe. use plumbers tape or dope.

Step 4: Assemble: Outlet Nozzle

Pipes:
3/4"-18" pipe (I had to go back and add a coupling and 3/4"x4" nipple so go with 24")
1 1/2" -1" reducer
1 1/2"x5" nipple

Use a vice to hold the 1 1/2"-1" reducer (wide side down) in place. Then use the angle grinder to make four equally spaced cuts (as close as you can is fine) about 1"-1 1/2" from the top (1" side). These vent holes provide extra air and helps to control the flame.

Dry fit the 1 1/2"x5" nipple on to the reducer, slide the 3/4" pipe in till its about 1/2"-3/4" (on the inside) from the end of the 5" nipple. Then mark the 3/4" pipe where it lines up with the 1" side of the reducer. This directs the flame further into the foundry keeping the nozzle cooler and it also helps prevent back pressure in the nozzle.

Clean and weld the 3/4" pipe (at the mark) to the 1" side of the reducer. Make sure it's centered. Use tact welds and a vice as needed.

I originally made mine a little too short and back pressure (from the reduction into the brick work) was heating up the nozzle, so I had to add a coupling and a nipple to compensate.

Step 5: Assembly: Fan Mount

This is for attaching the fan to the burner.

Pipes:
2"x6" nipple (variable)
2" floor mount

The blower I had didn't have any ducting to reduce it down to the 2" pipe so I improvised. I got some (specifically 4) 4"x6" roof flashing, cut a 2" hole in the center and bolted them to a 2" floor mount.

I attached a 2"x6" nipple on to the floor mount, then screwed that in to the middle spot on the T-pipe. This right angle to rest of the burner assembly provides air turbulence inside the mixing chamber, creating a better fuel-to-air mixture.

Use plumbers tape or dope on all the pipe fittings for this part.

Step 6: Assembly: Mixing Chamber and Completion

Parts:
Gas Inlet
Nozzle Outlet
Fan Mount
2' T-pipe
2"x10" nipple
2"-1 1/2" reducer
1 1/2"- 3/4' bushing

Mixing Chamber
Screw the 2"-1 1/2" reducer and the 1 1/2'-3/4" bushing together, make sure to use plumbers tape or dope. If you can find one use a 2"-3/4" reducer instead.

Attach the 2" end of the reducer to the 2"x10" nipple. Use plumbers tape or dope.

This will create the mixing chamber when attached to the 2" T-pipe.

Assembly
Attach the Gas Inlet to one side of the T-pipe and the Mixing Chamber to the opposite-- if not already done so. Make sure to use plumbers tape or dope for these connections.

Attach the Fan mount so that it is perpendicular to both the Mixing Chamber and the Gas Inlet-- if not already done so. Make sure to use plumbers tape or dope for these connections.

Screw the 3/4" end of the Nozzle Outlet into the 3/4' end of the Mixing Chamber. Make sure to use plumbers tape or dope for these connections.

Test all the connections for air leaks with soapy water before hooking up to a any kind of gas line. Always practice safety when ever using the burner.


Happy melting =)

Step 7: Meltings and Additional Info.

It takes about 1-1.5 hrs to warm up the foundry to the point where it will start melting aluminum and for the crucible to get red hot.




...also great for marshmallow roasting =D