Thread: Mini Forge - Single Burner Forced Air.

Originally Posted by kevint

I'll wanna look into that Chris. Thanks.

what do you think of this: forge

I like it. I have to be careful though; it wouldn't take much for me to go off the deep end and start collecting and building different kinds of forges just for the fun of it!

I travel to Duluth, MN fairly often and I'm always drawn to the mountain sized pile of taconite they have at one of the loading docks you can see right from the freeway. The taconite comes straight from the Mesabi Iron Range. I think it would be cool to build a small furnace, fenagle a trailer load of taconite from the company that ships it, and make a batch of steel.

When I was a kid growing up there, you could pick up buckets of taconite if you just walked along the railroad tracks in east Duluth. It was perfect size and shape for slingshot ammo. They don't use that particular stretch of rail for that purpose any longer so no more free taconite there.

Chris L

Originally Posted by kevint

Honestly i'd probably be more like this: Mini Forge

Kevin that is a helpful set of pictures that really show the tangential design for a tubular horizontal forge. It's easier to see the burner offset so the flame swirls around the inside of the tube heating everything more evenly.

The MAPP gas burners are good for very short run kinds of forging. In the long run that is very expensive fuel compared to a venturi burner running off a 20-100 lb propane bottle.

The 3 links you have been given are some of the best. There is another by Ron Reil here....
Site Map

I think you will find this site very informative.

Originally Posted by ChrisL

I like it. I have to be careful though; it wouldn't take much for me to go off the deep end and start collecting and building different kinds of forges just for the fun of it!

I travel to Duluth, MN fairly often and I'm always drawn to the mountain sized pile of taconite they have at one of the loading docks you can see right from the freeway. The taconite comes straight from the Mesabi Iron Range. I think it would be cool to build a small furnace, fenagle a trailer load of taconite from the company that ships it, and make a batch of steel.

When I was a kid growing up there, you could pick up buckets of taconite if you just walked along the railroad tracks in east Duluth. It was perfect size and shape for slingshot ammo. They don't use that particular stretch of rail for that purpose any longer so no more free taconite there.

Chris L

I worked in Mountain Iron, MN on the Mesabi range for American Bridge Co on steel erection at their US Steel taconite pellet processing plant back in the '70s. Lived in Chisholm next to Hibbing the bigger town where Bob Dylan was from. Where they had what was then the largest open pit mine in the US if not the world. Something to see that hole in the ground. Nice people out that way.

Originally Posted by JimmyHAD

I worked in Mountain Iron, MN on the Mesabi range for American Bridge Co on steel erection at their US Steel taconite pellet processing plant back in the '70s. Lived in Chisholm next to Hibbing the bigger town where Bob Dylan was from. Where they had what was then the largest open pit mine in the US if not the world. Something to see that hole in the ground. Nice people out that way.

I know that area fairly well. The range has seemed to be one of those places that were boomtowns in days gone by and largely seem to give off a feeling or depressed vibe. IMO the U.P. of Michigan has the same vibe. Too bad since both are beautiful places.

Chris L

Would love it if you could email me a copy of the plans

Thanks

TinMan

<DELETED PUBLIC EMAIL>
I deleted the email address since it would be harvested by spam bots.
Tinman, Scott indicated that you could PM him your email address.
Sincerely,
Bruno.
<DELETED PUBLIC EMAIL>

Tin man,
I would edit putting that in the open...spam bots will get your email adx. I doubt you want a bunch of junk. Send a PM.
Scott

Back on the forges. I too have been looking at making one, but I get conflicting stories & they actually make since to my pea brain. The pipe or round forge is the latest and greatest because it swirls the flame/heat, right? I question this theory. My question is this: What happens when you place your object into the forge for heat treatment? You have a total disruption of your "swirl" do you not? This is why I have been considering a dual burner from the top...what really is the "best"?

Thank you.

I'll try to explain this as well as I can. In an ideal GAS (this does not apply to most common coal or charcoal arrangements) forge all the heat would warm up the liner equally. It's not the flame that is heating the steel/object in the forge, it's really radiation or conduction of heat from the hot walls that's doing the job. The preference would be for even heating of the walls of the forge.

If you setup the burner to push the flame into the forge parallel to the diameter or radius of the tube, you will have a hot spot on the far wall opposite the flame entry. Hence uneven heating. In addition, the flame front has only a short distance to complete the burn cycle and this leaves an air/gas mixture that is incompletely burned that blasts directly on to the work piece. This will cause oxidation/scale formation at a much higher rate. More decarb, less steel when done forging.

If you setup the burner to push the flame into the forge parallel to the tangent of the diameter/radius, the swirling action around the longer distance involved allows for more complete burning. This equals neutral atmosphere, even a reducing atmosphere with attendant reduction in scale and decarb in the workpiece. The flame front does not directly hit the workpiece with a greater ratio of oxygen.

These rules apply to a horizontal tube configuration. If you add in the swirl to a vertical type (Don Fogg style) you also add the vertical distance for the flame to complete burning and improve the reducing atmosphere and scale formation.

For the most part, if the atmosphere is adjusted correctly, either forge style will work equally well. Once the walls of the fire are hot, you won't see much swirling anyhow until the flame front exits the forge and that is after it's done it's job. Then all you have to worry about is the hair on your arms, or beard, or eyebrows. If you put a heavy billet into one of these fires, you will notice one side heating more quickly than the other. Turning or rolling the billet evens that heat distribution (think like a baker or pizza maker) and eventually the whole thing will warm up evenly. Light billets or blade shapes don't disturb the flame flow that much.

Horizontal forges have the advantage of laying the billet down inside. This allows for a stub tang and the use of tongs to manipulate the billet. Vertical forges require a suspensory arrangement, generally accomplished with a welded on long bar that is used to manipulate the billet. But when that rod gets hot, and it's a heavy billet it can get droopy and difficult to hang on to. Horizontal forges will accumulate flux and melted refractory in the bottom and the billet might have some of that adhere and dirty up the work. A wire brush is handy then. In a vertical forge all that slops off well down in the bottom of the forge and doesn't get in the way. Those are the basic advantages and disadvantages. Hey, some folks like Chevys and some folks like Cadillacs.

Coal fire folks can get close but you need to build a big pile of coal and have an external source of coke to get the same sort of performance that an open LP fire will give you. PM me if you want that described.