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I Forge Iron

Forge problems


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I finally got my new forge running and I was rather disappointed in it. Before I go back to the drawing board, I was hoping that you fine folks might offer some simple tweaks that might improve performance.

In an effort to avoid confrontation with my local home owner's association (hopefully, I can start making presents for them soon, but first things first), I decided to use charcoal. This is available to me year round and is not too expensive for the amount of forging that I do. I constructed a small forge out of a discarded lawnmower body and am using an adobe-filled bucket with a one inch pipe passing through it for a fire pot. The pipe has two 1/8" holes drilled in it. I constructed a small, double-chambered bellows (about 18" in diameter) which has a 1/2" pipe nipple protruding from it. This is attached to the tuyere pipe via a piece of 3/4" flexible water heater conduit.

I have never really used charcoal before (I have always used coal) and am unfamiliar with its nuances. When lighting the fire, I put a lit piece of newspaper over the tuyere and got it going like the flame coming out of a blow torch (in terms of sound), but It took a long time and a LOT of pumping to get the fire hot. I put a piece of 3/8" rebar in to the fire and it seemed to take a long time to get hot. Additionally, I couldn't get the steel above orange heat (although it was hard to judge in the light). I was using natural lump charcoal, not briquettes, by the way.

Does anyone see any obvious tweaks here?

I would also like to add that the shop has no power (or I would have used a hair dryer) and I have limited tooling (my arc welder is in storage and I have nothing to plug it in to).


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Yes, larger and more holes in your air grate and a full sized bellows or at least twice as large as you made. The air output of a bellows is exponential compared to it's size, one twice as large puts out 4x the air so shrinking them means you get to the "why bother" point quickly.


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Hi Rob
i'm sure i've seen antique commercially manufactured 'portable' forges with 18 inch diameter bellows. I think they had a 1 inch air outlet all the way, even try a couple of sizes bigger. Old catalogues such as linked recently on the forum often have specifications eg;

good luck, i had the same problem matching tuyere size to a large blower i had to use.


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The key to a forge fire is volume of air, not air velocity, smaller holes will restrict volume (and increase velocity) which is not a good thing. Also the bellows do sound small. Over the last 3 weeks I built a pair of great bellows myself, and just the air chamber (without measuring the front 'cone' part is 48 inches long by 32 inches wide (overall length around 5 foot 3 inches long)


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I feed my tuyere through a 3 inch flex hose. I have an electric blower with plenty of capacity and had to use a speed control on the motor, plus I have a shutoff damper. Into the bottom of the fire box I cut two slots about 3/8" wide and 2 1/2" long. That allows all the air I need until the clinkers build up.

Jmercier, that is a great looking bellows. What size is your pipe at the end of the cone?

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I would change the nipple out of your bellows to at least 1.5" and get some more holes in the tuyere. Mine is actually a grate made form 3/8 rebar welded so it has a 3/8 space between the bars.

Air is the answer and it sounds like you are short on it.

Good luck.

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