Centaur fire-pot

[Don A]

I need some hint on how to mount a Centaur fire-pot. I was hoping to drop it into a simple steel table style forge. I was thinking of building the forge small enough to be portable, with maybe a ¼” plate for the top. I originally thought I could simply cut a hole and drop it in, but the fire-pot has the off-set rim and I’m not sure how to go about mounting it. I’d like to have the high edge flush with the table and still take advantage of the “gulley” down the center.

I know that a lot of folks use these, and maybe I am over-thinking the whole process, so let me know the best way to handle this.

[Strine]

Don, for portability ie less strain on the back muscles. might I suggest a much thinner plate than 1/4", and use a light frame to support the actual pot.

[Mills]

Don I would suggest for portability forget the cast firepot and make one from the 1/4". an oval about 1'x2' with a central inverted pyramid that is about 8" on the base, truncated to the size of a tee for air supply and ash dump, is a pretty light weight set up. Make the legs removable and you have yourself a nifty package if you can find a small blower to go with that.

I got called away before the original question was answered.
You will have to form a valley to match the offset, its the only way I can think of. I have used channel for this but you may not have a piece of that paricular size. With friends in the sheet metal business it may be possible to have one bent. You may have to cut and paste some plate or sheet to get the job done OR build a bender if your scrap pile allows. One last thought that is the easiest would be to have the bottom flange rest on a frame that you can can then buid up with fire brick, castable refractory, or a portland/vermiculite mix. That would then give you a fairly thick non portable hearth.

Enjoy!

[Don A]

Sorry gents... let me redefine portable:

I might need to move it as much as 15 feet, one way or the other. I don't care to go fairly bulky with it, just didn't want to go the masonry route and have it tied to the ground.

As for portable, I am working on a charcoal & bellows rig for demos and such. The coal forge will stay close to home.

... and I sure wouldn't turn down a good deal on a blower!

[Mills]

Well now that is indeed a horse of a different color! What I posted above is still suitable as the legs can be pipe with some nice casters or wheels, perhaps a frame that you could hook a two wheeler under. Jim C has a nice design that is well thought out, check in the blueprints for it I don't think you'd go wrong with it.

[HWooldridge]

A typical rectangular pot sits on the lower lips - the higher ones are used when the hearth is bricked. You can cut a hole as described, drop the pot into place, then put a layer of fireclay in place.

I wrote the following for "the place across the street" a while back - there is also some other info buried within that might be useful to someone...


By Hollis Wooldridge
2/11/05
Lining a Forge:

I lined a Buffalo forge that has the lips an inch or so above the iron hearth and it turned out well. The process is based on something I learned years ago when I used to help my grandpa build houses. In addition to carpentry, he did some rock work and one thing we would do occasionally is reline fireplaces. On horizontal areas, he would make up a mix, apply it dry and level, then spray water on top. This would rock up in a day or so without cracking. The mix I used (based on his recipe) was 3 parts mortar, 3 parts clean sand, 1 part fireclay and 1 part dry lime. I mixed it, poured in the hearth to a depth that was flush to the top of the firepot and raked it smooth, then sprayed only enough water on it until the surface was wet. I let sit two days before making a fire and it had hardened nicely with no visible cracks anywhere. I think the minimal amount of water helps eliminate the cracking.

Coal Forges:

I have seen more badly constructed coal forges than good ones in my life. A lot of folks make their own (which is perfectly fine) without a basic knowledge of not only how but why it works.

All solid fuels need some amount of air pressure to burn properly. You can have too much velocity with insufficient pressure or too much pressure without enough air movement. The two extremes can be illustrated by a couple of examples. A light wind blowing on a campfire will make it hotter but only the outside of the fuel pile burns because the breeze can't make it to the interior. Conversely, hooking an air compressor to a firepot will make a fire but any amount of pressure much over a few pounds will blow the fuel out of the pot. The reason why bellows and centrifugal fans work so well on a forge is that they generate the right combination of both air supply and pressure. Too big a blower (like a large, electric squirrel cage) will lead to excess fuel consumption, more clinker and an oxidizing fire. In addition, a squirrel cage can be "stalled" because they are designed to move large amounts of air - not push it thru a mass of burning fuel. Conversely, too little air will never allow the fire to reach its proper potential for heating.

The proper size air inlet to the fire is also important. I'm sure a lot of folks have used grates drilled with a bunch of holes but 1-3 larger holes is better. One of the best homemade firepots I ever saw had a 1/2x3" slot cut in the bottom. The pot was entirely made from 1/2 inch steel plate and there was no clinker breaker. This arrangement made a nice hot fire with a center about the size of a grapefruit, which is about like a commercial pot.

I recently exchanged notes with a professional British smith who uses a side blast. It is simply a piece of 1" heavy wall stainless tubing as a tuyere and aimed slightly downward into a molded mortar "duck's nest". The coal is piled up in the hearth and forms it's own bed in the depression. Other fire shapes can be made by employing fire bricks to redirect the blast. This simple arrangement works well and eliminates all the Rube Goldberg creations that get built in back yards. The smith said he can easily weld with this design and some of these forges have lasted over 5 years in daily use.

I use a coal that generates a big clinker in a hurry but it was cheap, gets hot and cokes well so the only disadvantage is the dirt. Therefore, I have learned to build a fire and use it for half hour or so then let the clinker cool for a couple of minutes. At this point, there is enough to usually pick up in one piece while I try not to disturb the coke around the pot. I can usually clean the fire and get back to work without breaking the whole fire down.

If I have one piece of advice about fire tending, it's that less is usually more. I have seen a lot of people that tear the whole fire down on every heat or spend the entire time digging up the coke ball. A fire has to form a natural bed to work properly and it takes a few minutes for this to occur. A good coal smith will replace the piece for the next heat and rake a little coke on top. As the fire burns hollow, the sides are pushed in a bit. This gentle management is done during every heat - you don't work for an hour and then tend the fire all at once.

[rthibeau]

Don H. - I did almost exactly what you're describing, I think. I also got a Centaur fireport and placed in a cut out in 1/4" plate. The flanges left and right are above the plane of the plate, but the front and rear are at the same level as the plate surface. There was a gap front and rear, but I placed angle iron in them and that worked. When working, coal is piled around the sides and rear, so the raised edges of the pot aren't apparent. The side draft chimney is metal 10" stovepipe sitting on the plate inside chimney block, bottom one and some cut out as is the pipe in an arc. The whole affair is sitting on top of four columns made of concrete block piled up - no mortar anywhere. The plate is 4' x 4' with 1" square tube welded all around the bottom as a frame, very heavy, very stable. The whole thing can be taken apart easily and reassembled. It works great, has a large work area, and I can forge weld with it.

[rthibeau]

I take back the easily part - all that block and especially the plate table are very heavy and moving it piece by piece is still a lot of work.
But it is portable in the sense it can be dismantled and reassembled in short order.

[Strine]

Sorry Don I thought you were thinking carry-on luggage portable

[lee]

I used a centaur for my portable forge...cause I had it and like a deep fire pot.I used a plate of iron....I'm thinking without going out and measuring..3' by 4'(second thought says 2' plus by4' cause I had it) .I cut and welded legs and braces to it.I I welded sides on with some two inch iron I had...all around as a lip...with sections cut out were I would insert my iron or have it stick out beyound.I cut a hole out the size of the pot where I wanted it...closer to the working end....maybe 8 inches.I welding lips on the botton of the hole where the pot would set.I connect pipe to the air intake end that could be disconnected and flex hose from that to the blower.Two I welded half inch iron on both sides out enough to hang tools on...sort of rib still for strength too as a carrying handle.

I take it apart by disconnecting the pipe that rest on a large welded horse shoe(cause I had it)as a rest...lift out the pot...turn it on it's side and use a dolly to move it.It's my go to school forge or move around outsider for where ever is convenent to play.

It's not perfect but it's Ok and as effective as my factory buffalo forge I aguired by chance one day...but really enjoy....heavy though with hood and refactory poured on table.Deep pot and good control on a blower to me is a big key.I think It was a little narrower than I said and I decided if done again I would go three foot wide or whatever it takes to use my shovel down both sides without hitting the edge of the pot which is a little thicker than the iron table.But it works an I could make a narrower shovel easier, maybe?Oh the trials of a wannabe.

lee