My vertical forge build

T

Tenebr0s

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Jun 3, 2012
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I thought I would make a thread as I slowly build my vertical forge. Maybe this will also help me from making too many major mistakes.

Right now I am still gathering materials. https://imgur.com/gallery/DjnYWyF

The body of the forge is an old air tank I got from the scrapyard (12” diameter). Inside that is going an 8” stovepipe wrapped in two inches of insulwool. Inside the stovepipe I have a 6” high density foam roller which will be a hollow form for the forge chamber. I’ll be pouring kasto-o-lite to from a 1” liner inside the stove pipe. All this of course after I’ve cut out and inserted the square tubing for the doors and the burner tube.

I am wondering about burner placement (it’s a blown burner). I have seen that it’s placed about 3” from the bottom at a 90 degree angle to the forge doors. To help form a cyclone, I think it’s supposed to be at a tangent/not sticking dead center into the tube? How far off center is it supposed to be?
 
I angle them up at around 20 degrees and sideways at about 45 degrees. Tuus makes an upward cyclone of fire.

Place the burner port so it is at least 2" above where the floor will be. If the floor is 3" of kitty litter, put the port so the bottom of it is 5" .
 
Ok, thanks Stacy. So you actually have the hole/burner port dead center, just angled? I was thinking it should come in off-center like this:

https://www.iforgeiron.com/uploads/...5349.jpg.981b22625d0e477a7a877e54a543a7c5.jpg

Stacy E. Apelt - Bladesmith said:
I angle them up at around 20 degrees and sideways at about 45 degrees. Tuus makes an upward cyclone of fire.

Place the burner port so it is at least 2" above where the floor will be. If the floor is 3" of kitty litter, put the port so the bottom of it is 5" .
Click to expand...
 
Off-center on a circle is imppossible.The link is what I was saying. Angle it so it is at a tangent and tilt it slightly upward.
 
While I'm waiting for the refractory materials to arrive, I thought I would get started on the forge body.

I cut off the top
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Then I cut out the bottom with a 6" hole saw
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I then raised the edges of the cut off top on the anvil to form the body of the lid.
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The foam roller fits inside the bottom hole and an 8" stovepipe will go around it.
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I liked the idea of leaving metal on the bottom to support the weight of the cast liner, but I'm wondering if it will end up causing the body to over heat...
 
Cut a doughnut circle of insboard and put it in the bottom when pouring. Add another on the top when done. This will help insulate the ends.

A vertical forge generally gets pretty hot on the ends anyway.
 
I am wondering about how far in my burner tube should go. I had initially planned to cast the forge liner with the tube in place, which would mean the burner tube terminates right at the wall of the forge chamber... But I’m concerned that this would cause the tube to overheat.
 
One solution is to weld in the burner port tube with it ending against the liner. Curve the end to fit flush if you want.. Carefully bore a hole through the refractory (not as hard as it sounds) and use some satanite to make a smooth bell shape transition into the chamber.

On your 1" thick liner, position the burner end about an inch back from the chamber wall. Play with the burner in/out position to fine tune the flame.
 
Ok, thanks, Stacy. I’m thinking I could make a cardboard tube extension for the steel burner tube. So, have the burner tube terminate at the 8” stove pipe and have the carboard for the last inch of liner, which I can then remove or burn out.
 
That would probably work. I would pack the cardboard tube with wadded newspaper to keep it rigid when it gets wet. Might be a good idea to wax the tube or even spray paint it.
 
Now I’m thinking the cut-off top of a seltzer bottle might be the perfect shape for casting the nozzle... (the one I have is more conical than the typical rounded soda bottle). Should the nozzle increase to about double the blower tube diameter?
 
I think you are trying to overcomplicate this liner. The more things you add to the pour the more places something can slip or mess up. Make a plain cylinder.
Just pour it and make the holes where you want them. Use a flame burr, a masonry bit, and old drill bit, or a spoon. It isn't like you are drilling granite.
Ream them with any hand too to get a little flare. These aren't rocket nozzels after all.
 
I've been making some progress on the forge. All this would have been a lot easier with a MIG gun, but here we are.

After cutting a hole in the forge body, I made a bracket for the burner tube out of some angle iron. I have since replaced the set screws with shorter ones.

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With the bracket in place, I can have the tube in the right position.
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I haven't cast the liner yet. My plan is to grease the tube and cast it in place.

I made some flanges to go below the door tubes, and also bolted some corner brackets to the sides. The tubes are drilled and tapped and will be bolted to both the brackets and flanges.
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I cut out a hole in the front door and inserted a piece of smaller rectangular tube in it, which freely slides up and down. The idea is that this will both serve as a heat shield for me and also be heavy enough to weigh down smaller pieces and keep them from falling into the forge. I'll attach an eye bolt to it so I can lift it with tongs. I may also fill it with an insulating fire brick.

I drilled 4 holes both in the body and the internal stove pipe. Bolts go through the holes with nuts on the inside of the stove pipe. This should hold it in place when casting. The picture only shows two of the bolts in place.
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I wanted the forge to have a hearth, so I've been planning it around that idea. The forge will be suspended from the doors on a tool stand with a cut out steel plate as the hearth.
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With the forge supported by the doors, the floor will be removable when necessary. The body of the floor is a brake drum, which I bolted to a cheap jack stand. I am planning to make a kind of bundt cake pan shape, with a 6" circle of insulboard in the center, over which I will pour kast-o-lite and then fill with kitty litter.

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So, that's it for now!

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Cut the threaded part off the burner tube. I assume it is for the photo only, but just wanted to make sure.
 
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I had a little more time to work on the forge today. I lined the forge with insulwool and bolted everything together. Tomorrow, finally, I will cast the liner. My friend, commenting on the unintentional steampunk look of the forge, joked that it needs a periscope. I laughed... then I started thinking. Visibility is pretty poor with this setup, and I don’t really want to stoop down and look into the forge every time I want to check if the steel is up to temp. The back port is cut at an angle, because I’ll be putting a swinging door on it. It might not actually be such a bad idea to set up a simple angled mirror so I can stand to the side, open the door with tongs, and take a peak at what’s going inside.

Edit: it probably goes without saying, but I ground down all the bolts that go into the ports so they’re flush
 
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You are starting to over-build it.

First, you don't want to close off either port. At most, you can throttle the back port a tad with a fire brick. The air and gas coming into the forge creates a pressure. The burning gas greatly increases that volume. If you close off the ports.... where are the exhaust gasses going to go. For a blown forge your size, you want about 15 to 20 sq.in. of exhaust port opening. That is roughly a 3X4 front port and a 2X3 back port. Block them off and the burner will back flame. You really don 't want that to happen. You absolutely have to havce at least one open port.

Your drop door is a bad idea and should not close. The steel gate is not only unnecessary, it may be a problem when it gets heated red hot. If you keep the drop gate, replace it with a plain old firebrick. The back port has to be of sufficient size to handle the exhaust if the front is blocked. Personally, I would get rid of the gate entirely. If you want to throttle the port a bit, just set some firebrick around it to make the port smaller.

Your heath is fine. Actually, a good idea.

The insboard floor covered with 2" of kitty litter is fine. You don't need a cast floor in the arrangement.
 
Thank you! I had not thought about the exhaust... I will at the very least have to keep that back port open. The main reason I wanted the drop door in front is because it’s very effective at weighing pieces down (at least, to the extent that I’ve been experimenting with it so far). I would really like to keep it, if possible. But I’ll definitely modify it so there’s no steel facing the inside of the forge. If the back port ends up not being sufficient for exhaust, would it make sense to have a hole in the top of the lid?
 
No, just build it like a vertical forge should be built. Two ports across from each other.

If the desire is to have something hold the bar or billet handle down, use a block of steel or a firebrick on the hearth. You could easily make a simple catch bar by welding an 3"X1""L" shape piece of round or square stock on the hearth lip. Weld the short leg to the hearth, slide the bar or handle under the other leg to keep it in place.
 
I really appreciate you walking me through this build. Not thinking about the exhaust is exactly the kind of stupidly obvious mistake I thought I would make. You most likely just saved me from a significantly dangerous situation.

I hope you won't find this question argumentative –– I am really just curious. Other than the fact that it makes the build less complicated, is there a reason I want exhaust coming out at both ports, rather than putting adequate ventilation towards the rear (or top)? For example, it would be pretty simple to cut two slots (one in the lid and one in the upper rim of the forge body) at the back of the forge, which would give me plenty of exhaust. As long as there was refractory in place, it would keep the metal from overheating. On the other hand, propane melting furnaces have a hole directly in the center of the lid; I'm wondering if this improves the cyclone effect in the forge and/or allows more of the fuel to be completely combusted since it has to travel a greater distance inside the furnace.
 
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