Forced Air Burner Forge Build

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Nov 15, 2005
Messages
1,194
I'm starting this tread to document my forced air forge build. Maybe someone can learn something from my build and maybe yall can tell me if I'm screwing something up!!

Thanks for any insight along the way.

Tonight I test fired the burner. I still need to get a gauge and a needle valve... but what do yall think?...

Sorry it's ugly... had to piece together fittings from Lowe's and Home Depot to make it work.



Video:









Cheers,
James
 
Looks good so far.

I would add a Quick Connect propane fitting where the hose attaches. It is no a good thing to have the hose running across the floor when not needed. They are cheap from High Temp Tools and Refractory. You buy the female and male parts separately for $14 and 3.50, respectively. Put them on all you gas hoses and devices. I have them on both ends of the hose so I can snap the hose on at the tank and at the forge, and roll it up when not in use. A rubber cap is available for $2.50 to seal the QC when not connected. A rubber cap from the auto parts store will cover the male fittings when not in use if you have wasps and spiders who like to go up inside anything with a hole. http://hightemptools.com/valves.html


Funny story about mud wasps. I live with them, as they don't cause any harm. When they put a nest on a wall or place I don't want it, I knock it off. I have a retractable power cord hanging outside the grinding shop to pull power out in the smithy as needed. It has a triple outlet on the end. I grabbed it a couple days ago to plug in an angle grinder and all the holes were plugged with dried mud. I unplugged the other end and cleaned it all out, but that was a first for me. They do love to get up in the forge burners when I am not using it enough. That usually gets resolved pretty quickly when I light the burner, but I have had to take one down and remove a large dauber nest when I had an extended non-forging period.
 
The flame looks too rich in the video. The needle valve should remedy that since you can fine tune the fuel.
 
Update:

Got the shell constructed. This forge is going to be made from an old air tank. It's OD is 10''. The plan is to wrap the ID with 2'' Kaowool, Satinite, and ITC-100. I'll lay hard firebrick for the floor. I plan on using hard firebricks as sliding doors on the angle iron tracks in the front and back. The front will have about a 6'' diameter opening not including the brick floor. The back opening is ~ 4''. I'll cut out a 10'' circle of kaowool with a 4'' circle in it for the back, then line the ID of the shell.

The overall length is ~ 15.5'' with a working space of 6'' x 13.5''

The burner is slightly above the center line of the forge, point down and back. The hope is that this will create a nice spiral once the insulation is installed.

I plan on plugging the little 3/4'' port on the top, but leaving it for the future. It's the perfect size for a ceramic sheath.

Next thing I need to do is build a stand... I'm thinking 4x4s with some casters on each foot so it's mobile. I'll add some shelves and set up a spot on the back for the propane tank (like a welding cart).

I made an order from "high temperature tools & refractory" today with the necessary supplies... Didn't get an email receipt.. hope they're still in business! (http://hightemptools.com/supplies.html)

Cheers,
JK




 
Probably too late now, but the burner should be pointed on the tangent to the chamber so the flame curls around the walls. As you have it, it will go straight at the other side making a hot spot. I recommend the burner coming in at the tangent and angling between 15° and 25° ( depending on forge length).

All this is in the drawings and plans in the Stickys.

I suggest placing the needle valve in the pipe nipple where the propane hose attaches.
 
Probably too late now, but the burner should be pointed on the tangent to the chamber so the flame curls around the walls. As you have it, it will go straight at the other side making a hot spot. I recommend the burner coming in at the tangent and angling between 15° and 25° ( depending on forge length).

All this is in the drawings and plans in the Stickys.

Damn... you're right. Looks like I wing'ed (eyed) it too much.

The yellow line below shows the current trajectory and the red circle is where the kao-wool should be after install. As it is, it will be hitting the edge of my brick floor it seems.

Is the Blue Line the ideal angle of the burner?

 
Well, the new iteration isn't perfect... but hopefully it's better. It'll have to do. After looking at it on the computer it could do to point up some more, but too late. I should be able to get a degree or 2 more by tweaking the holding bolts.

 
Here is the wooden rolling cart I made for the forge with forge and burner in there clamped in. Took a while to arrange it so that I could see in the forge and manipulate the air and gas valves. The set up needed to be mobile since I don't have a dedicated smithy. I had some old wheels lying around from a welding cart that I got to utilize.

I plan on putting a steel plate down ~2'x1' under the forge, then welding the forge to it, then affixing the plate to the cart.

Then maybe wiring up an outlet with a switch for the blower and ESD solenoid.



Cheers,
JK
 
I actually prefer a burner angle like the one you ended up with. It's kind of a pain to get the wool right when the angle is more extreme....
The only issue I see here is that you may well have too much burner for that forge. That burner would work well for a forge with a 10" round inside diameter after 2" of wool...
I have a 14" OD vertical forge, with 10" inside chamber, 14" tall inside, similar burner, and it's crazy hot with very low fuel consumption.
 
I actually prefer a burner angle like the one you ended up with. It's kind of a pain to get the wool right when the angle is more extreme....
The only issue I see here is that you may well have too much burner for that forge. That burner would work well for a forge with a 10" round inside diameter after 2" of wool...
I have a 14" OD vertical forge, with 10" inside chamber, 14" tall inside, similar burner, and it's crazy hot with very low fuel consumption.

Thanks for the info about the angle. Good to know. That's slightly concerning about the burner sizing, but hopefully I can tune it low enough to accommodate my shell. We'll find out for sure!
 
Hey James, where are you at in TX? If your enclosure ends up bring too small, I’ve got some heavy walled 12” id pipe that I would be glad to give ya, if you are relatively close.
 
Hey James, where are you at in TX? If your enclosure ends up bring too small, I’ve got some heavy walled 12” id pipe that I would be glad to give ya, if you are relatively close.

Thanks for the offer Mr. McPherson. I'm in Midland,TX. Hopefully my current setup will work, but we'll see! If not I'll have to take you up on it! Or redesign my burner.
 
Hey, you’re actually pretty close in TX terms! I live up in between El Paso and Carlsbad. Let me know and I’ll cut you off a chunk of this beast!
 
That is a big blown burner. On my verticle forge I used a 1” burner tube and that forge is 12”OD and had 1”-1.5” lining and it got way hot. Personally if it was me I would reduce the burner pipe to a 1” burner. Blown forges need a certain amount of velocity to keep the flame inside of the forge and out of the burner. When you drop the air speed down to low the flame will actualy pop and jump into the burner tube. What’s happening is your air needs to be faster then the flame speed. That’s why lots of burners use flares. A flare drops the air fuel velocity as it exits the burner. This is why thy take such nice pictures out side of the forge. The flame sticks to the edge of the flare so you can crank it up higher when it’s in a vise. But in a forge a flare really does nothing. The forge acts like your flare and once it’s hot it will run smooth. So your problem could be bigger then you think. When you run to large of a burner 2 problems unfold. First you can’t adjust it down low anough because of flash backs and 2 you can get your forge hot enough. I know that this might sound weird but it’s true. Bigger burner = more heat your thinking. Yes that’s true but bigger burners need more distance from burner to the refractory. You can tell a burner is to big when you look in the forge and you don’t have a hot spot. You will actualy get the opposite thing happen. You will get a cold spot that is about twice the size as your burner. The Problem is the flame does not have enough room to burn and it’s the cold gas hitting the wall of the forge. Then what happens is most of your air and fuel burns on its way out of the forge openings. So like I said I would drop that burner tube down to at least 1”
 
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