Building a Coal forge - input appreciated.

Hello all-
As payment for one of the knives I made, I've got the services of a very talented welder to help me make a new forge from the ground up.
While it can be a simple job, I think I want it to be able to forge the length of a sword blade- I don't have any particular plans regarding smithing a sword, but I may want to do it some day, and I like to plan ahead.
So, the question I have been asking myself if whether it would be a better idea to make a coal forge with a standard round firepot, or to design a air channel and manifold that would allow me to blow air along the length of a longer pile of coal/coke all at once.
Per some previous posts on this topic, I think I am going to be making the forge table from 7 ga 1008 hot-rolled steel, rather than going with stainless steel, with the firepot or manifold mounted under the table and a grate for the coal to sit on- but I am not set on that design.
So, if you were able to make a "dream forge," what features and design would be the best to include? Complexity is no barrier in designing it, I am just trying to make sure that I make the best one I can- if that includes a lot of extra parts or design time, I am fine with that. I've got the use of the laser cutter, brake presses, and whatever else might be necessary, so it can be fancy if there is any reason for it to be- even including things like making multiple air channels that direct the air so that it blows in from the side rather than the bottom, or using tuyeres rather than a firepot. The main thing here is useful design, not ease of construction, so go nuts with the suggestions- I am just not experienced enough with a coal forge to believe that I know everything that could be involved.
Any suggestions?
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IMHO Adaptability is one thing I'd do again when building a forge. Go ahead and make the fire pot as long as you want and then buy or fashion firebrick to fill in any section you may not want at the time. Most of the time a small fire is all you will want.
I sure did say "want" a lot didn't I? Of course that is what this thread is about.
I have seen two variations of forges with the air blast coming in from the side that would work well with piling firebrick in the unused section. One was just a pipe with holes drilled in it, the other added a small angle iron "tent" above the pipe to protect it from plugging.
A complex design is OK as long as it is easy maintenance. Parts that will need replacement from the fire pot on up should be plug in.
Mike Graf
Prometheus wrote:

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The reason the most firepots have air coming from the bottom is so the air has to go a long distance before it hits the workpiece. So, since you put the work on the top, the bottom is farthest away. Also, gravity is going to make the ash and clinker go DOWN, so DOWN is where you have to get rid of it FROM and that's why most firepots have cleanouts in the BOTTOM. It is fortunate then, that one can install a clinker breaker in the center of the tuyere to keep all the coal from falling through, while still using that same opening to drop ash and clinker through to the outside world. I am sure that you know that most firepots use a "T" under the tuyere, with the air coming in from the side and a closure at that bottom for ash, etc to drop out.
Don't mimimize the need to intermittently clean the clinker out. It is a constant process with a coal forge. With the design I mention above, it is a simple matter to do the cleaning without loosing the fire. With other designs, you can loose the fire while cleaning and then have to start all over again. I always clean the fire before forge welding, and then again every 15 minutes or so when I am welding continuously.
I have a large old forge with an adjustable length firepot that I have been trying to get rid of for years. It has a moveable casting in the bottom of the firepot that would allow one to have a short fire with a short tuyere at one time and a long fire at others. I don't know how they held the coal up when the fire is "long" but they must have had a way. I'd like someone to to take this away. You could use it as a thought provoker.
Personally, I like rectangular firepots better than round ones. "Deeper" (at least 2 or 3 or more inches)is always better. I hope you don't plan to make the firepot itself from the 1008. It won't last very long. Cast iron is the way to go. I'd save my money and buy a ready made firepot if I couldn't make it from mild steel that's at least 3/8" thick. Even then, it won't last too many years if you use much coke.
The 1008 will be fine for the forge table.
I'm sure you have already googled "coal forge" and "blacksmith firepot" and read some books on the subject.
We have used at least a dozen of these firepots in the past several years to refurbish worn out forges:
http://www.centaurforge.com/prodinfo.asp?number ΞNTVULCANDP
Pete Stanaitis ---------------------
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Pete, if you have a picture of your adjustable forge,I'd be interested in seeing it.
I tend to build shaped fires with my pile of fire brick if I have something to heat up that doesn't work with my round firepot.
Mike Graf
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I'll go out there and see if I can get enough snow and ice off of it to get a good picture tomorrow, if that's alright.
Pete Stanaitis -----------------
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I can wait until spring if need be. Satisfying my curiosity isn't worth having to dig in the snow.
Mike Graf
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I took three pictures and they will be at: www.spaco.org/AdjForge.JPG www.spaco.org/AdjForgePot.JPG and www.spaco.org/AdjForgeBox.JPG for a few days. I don't have any idea how all these part go together, but I assume that the "box" part must have been hung under the firepot in such a way the it can be moved back and forth to change the amount of opening. As you can see, this "box" has fallen down inside the forge, still connected to the forge by 2 adjusting rods of some sort. So there must have been some sort of baffle that would keep the coal/coals from falling through as you made the fire smaller. You can see the inlet tube in the near side of the box. Must have been attached to a flexible pipe.
Hope this helps, Pete Stanaitis
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I made a sword forge.
It's about 1.2 metres long, and it's used to heat up long pieces of metal for heat treating only. There is no point to heating up that much metal to beat on, as bu the time you've go a couple of good whacks in the metal is cooling off. Also it's a pain in the ass to manipulate a piece of hot metal the length of a sword.
Anyway I digress. I use charcoal in mine, but could just as easily use any other solid fuel.
The details :- It's made from 1/2 a 6" diameter steel pipe, with a 1/4" wall thickness. I cut this along the length of the pipe, put on some legs. The tru-iron (excuse the spelling), is a length of 1" pipe with an end cap, drilled with 1/4" holes along it's length.
This heats up metal sufficiently, however it does require a fix. The forge isn't deep enough, so I will be adding some metal sides to increase the depth.
Regards Charles
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Forgot to mention, it can stand up on its end in a corner so it's out of the way.
Regards Charles
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<snip> Never done it but a knowledgeable Canadian Blacksmith told me about using a 4" thickwall pipe and drilling a length of hole patterns along its top. These holes accept short lengths (1"?) of 1/4" or 3/8" inside dia. pipe, which are welded to the 4". Rivets can be loosely placed in those short pipes (nozzles) to form the firepit size. An end cap on the non-blower end, can be removed to pull the ash out of the 4" pipe with a long handled oval scraper. From the TV show about the Japanese swords, one needs a long firepit to heat the entire blade at one time prior to the quench.
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2nd send <snip> Never done it but a knowledgeable Canadian Blacksmith told me about using a 4" thickwall pipe and drilling a length of hole patterns along its top. These holes accept short lengths (1"?) of 1/4" or 3/8" inside dia. pipe, which are welded to the 4". Rivets can be loosely placed in those short pipes (nozzles) to form the firepit size. An end cap on the non-blower end, can be removed to pull the ash out of the 4" pipe with a long handled oval scraper. From the TV show about the Japanese swords, one needs a long firepit to heat the entire blade at one time prior to the quench. A long quench tank too.
--
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Hi theChas,
A 4" wall thickness, how the hell did he lift it? A crane I hope.
I does sound like a good setup though.
I was thinking of making a small tempering device/forge. Basically a section of the 1/4" wall thickness pipe I have spare, welding the bottom up, putting in a side blast tru iron (I just like them 'cause you don't have to clean them), and a lid.
The lid, would be a section of the same pipe, that section cut in half so I'd have half a cylinder, then heat and beat to get a the section a little more severe, rounding the edges of course so I limit scratching the metal.
Heat up the forge, stroke the back of a single edged knife across the top of the cylinder.
For double edged knives, I could rotate the lid (or just move myself 90%, and stroke the middle of the knife.
The idea is that the heat is applied where I want it.
Regards Charles
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. . . . . I guess I wasn't very clear about that...4" pipe with 1/4" wall thickness..... The idea of using loose rivets to plug the air hole so one could adjust to air as to have a large range of 'fire sizes' is what I liked about his idea. He also told me about an English type forge where there is a water tank and at the height of the blower tuyree, a 4" Stainless horizontal water pipe has a 2" SS horizontal air pipe inside of it. projecting from the water tank. The end of the 2" is coned somewhat to make a nozzle. This air pipe goes all the way through the water reservour. So the tuyree, the 2 incher, is then water cooled....a horizontal air blow. Should be next to spotless to clean the inside. This could be clearer I know.
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When Chilla put fingers to keys it was 1/30/08 8:08 PM...

Another thing to try: Tempering tongs
I haven't played with them much yet, but I'm liking them so far.
--

Carl West
http://prospecthillforge.com : The Blacksmithing Classroom
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Carl West wrote:

Well this does sound a tad less effort than making a tempering forge, however how would your tongs stack up to a temper, maybe 3-4 feet long?
If it would be ludicrous to attempt with tempering tongs, maybe the tempering forge would be a better option.
It wouldn't need to be powered by charcoal, I could have a small burner under a piece of severely curved 1/4" plate.
Regards Charles
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When Chilla put fingers to keys it was 1/31/08 6:54 AM...

Y'do a bit at a time. That way you can see what you're doing every step of the way. If I were in a hurry to do the tempering and was doing a lot of it I'd make several pairs of tongs and cycle them in and out of the fire as needed until the blade was done.
There's a bit of art to using 'em and like I say, I've just started but they seem to give more control over heat-placement than a propane torch and work faster too. I've just been using some _heavy_ tongs that came as parts of lots with reasonable-sized tongs in them.
--

Carl West
http://prospecthillforge.com : The Blacksmithing Classroom
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Carl West wrote:

Thanks Carl, I'll mock up some tongs and give it a go, if I don't like it I can always try Mr. Hrisoulas's idea later.
Regards Charles
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3rd send <snip> Never done it but a knowledgeable Canadian Blacksmith told me about using a 4" thickwall pipe and drilling a length of hole patterns along its top. These holes accept short lengths (1"?) of 1/4" or 3/8" inside dia. pipe, which are welded to the 4". Rivets can be loosely placed in those short pipes (nozzles) to form the firepit size. An end cap on the non-blower end, can be removed to pull the ash out of the 4" pipe with a long handled oval scraper. From the TV show about the Japanese swords, one needs a long firepit to heat the entire blade at one time prior to the quench. A long quench tank too.
--
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<snip> Never done it but a knowledgeable Canadian Blacksmith told me about using a 4" thickwall pipe and drilling a length of hole patterns along its top. These holes accept short lengths (1"?) of 1/4" or 3/8" inside dia. pipe, which are welded to the 4". Rivets can be loosely placed in those short pipes (nozzles) to form the firepit size. An end cap on the non-blower end, can be removed to pull the ash out of the 4" pipe with a long handled oval scraper. From the TV show about the Japanese swords, one needs a long firepit to heat the entire blade at one time prior to the quench. A long quench tank too.
--
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<snip> Never done it but a knowledgeable Canadian Blacksmith told me about using a 4" thickwall pipe about 3 to 4 feet long, and drilling a length of hole patterns along its top. These holes accept short lengths (1"?) of 1/4" or 3/8" inside dia. pipe, which are welded to the 4". Rivets can be loosely placed in those short pipes (nozzles) to form the firepit size. An end cap on the non-blower end, can be removed to pull the ash out of the 4" pipe with a long handled oval scraper. From the TV show about the Japanese swords, one needs a long firepit to heat the entire blade at one time prior to the quench. And a long quench tank also.
--
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