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I Forge Iron

Forge hood

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Forge hoods are notoriously inefficient as the the smoke opening is so far away from the fire and any movement at all of air will blow the smoke all over the place.

A side draft exhaust down close to the fire is the most efficient and will also draw a good portion of the heat out too. With a properly made side draft exhaust the fire will actually be pulled into the opening along with the majority of the smoke.

the opening should be about 10 inches wide and 11 or 12 inches tall. If you don't use a big enough pipe it will still draw some but not very efficiently, 10 inch minumum preferrabley larger.

this is one Honest Bob had for sale at Possum's hammer in.

these show the draft or suction of a simple 8 inch pipe opened at the bottom for a small forge.

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These pictures are great in that they tell most of the story. I have this style in my home forge and I go horizontally through the wall and into a T's stem. The stack is supported from one branch of the T by pipe down to the ground where it rests on some bricks. Make the rest of the stack tall to draw well. No stack cap is needed cuz the rain goes to the ground. IMHO, the big diameter shown in the photographs is good and worth the money and any bs that is required to get some. I first saw the scheme at ABANA Alfred at each of the forging tents courtesy of Missouri smiths.

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My permanent coal forge with hood:


This is a material hopper, turned upside down, with a lid welded on the former opening, then the feed end was cut to accept a 12" round pipe. The cutout has a short (3") lip above it that helps when the fire is just starting but is short enough to not be in the way. The light colored items are firebricks that I put in just before the picture was taken as an experiment to see if they would hold heat and let the forge stay warm longer, thereby pulling smoke better while the forge was idle. They do seem to work on long runs once the bricks heat up.

This hood pulls well. I have a window off to the right that sometimes makes for little wind eddies but that is the only thing that disrupts the chimney. Sometimes with a big fire, I can hear a roar from the air cyclone moving in the round duct and every couple of months, I sweep an inch or so of very fine coal dust out of the back of the box, where a lot of it seems to cool and fall out of the air column.

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