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I Forge Iron

Electric blower bypass


HammerDance

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I’ve got cheap/free access to small electric blowers from time to time that I think would be (close to) ideal for use as a forge blower. However, these will all have a little bit too much oomph (scientific term), so I’ll have to dump some of the air with some sort of bypass so that the high static pressure doesn’t burn out my motor. Simple enough. 
 

My question is, is there something useful that I can do with that excess airflow, besides just dumping it back out into the open air? Would it serve any sort of purpose in inducing draft in the flue? Or should I just use it to keep the stink away from my boots? 
 

I’ll be able to ramp these down quite a bit, but there will still be extra air to get rid of.

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That was my first thought, but then I came across a thread (somewhere in here, I believe) about gasses finding their way into idle bellows/blowers, and then igniting and creating a bit of a blowout. Didn’t want to aim that at my face, but a simple backflow/check would prevent that, I guess. Scared myself out of that option at first, but now air conditioning doesn’t sound half bad. 

Cool! As a chronic over-engineer-of-everything, JABOD is still my favorite concept. It keeps me from trying to reinvent the wheel (in most cases).

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A blowback valve would definitely be over-engineering: if the blower is running, no gasses will back up. If the blower is off, shut the gate valve, and no gasses will back up. Since there is no direct connection from the tuyere to the waste air vent, there is no possibility of a blowback coming at you anyway.

Gasses backing up are only a problem with blowers or bellows that are used intermittently (i.e., standing idle between heats). If you're running an electric blower with a gate valve, all you have to do is keep the blower running all the time and adjust the valve as needed, depending on whether you are heating or hammering.

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I guess I see an idle blower and an idle bellows as the same empty chamber when not in use. BUT leaving the electric blower on at a whisper makes sense anyway, so I suppose my concern was moot anyway. Thanks for the input, I was overthinking it. AC it is

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Why fuss with the electric blower speed controls all the time?  Set them for the way the blower runs best, direct what air the forge needs to the forge and direct the remainder toward the blacksmith.  Not directly toward or on the blacksmith, but provide a stream of air not aimed at the anvil (would cool the metal) but so the blacksmith can take a half step back and be in the air stream.

Summer was the operative word in my comment as it will be 31*F Saturday with a low of 10*f Saturday night.  

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The smoke from smoldering solid fuel, coal most notably is flammable. If it builds up in a pocket it MIGHT ignite when a fresh blast of air hits it and bring it into a flammable mixture. 

The easiest way to avoid this is to mount your bellows or blower above the fire IF you're using a bottom blast forge. If it's a side blast the unburned gasses don't seem to flow into the bellows or blower. I don't know why not but I don't hear about side blast forges popping.

Mine only produces little hardly noticeable pops and loud pops rarely. I THINK that's because the ash trap section of my tuyere is deep compared to the vertical section between the horizontal supply and the air grate. Any burning coals or HOT clinker falls well below the air supply so any unburned gasses don't have an ignition source when fresh air hits the system. Fresh air goes UP, not DOWN to the out of flammable range gasses and HOT debris below it. 

Mine is similar to Bob Patrick's but is made from exhaust pipe and has a clamp on exhaust flap cap for the ash dump.

The couple times it's popped loudly it just opened the ash dump and cleared the ash into the water bucket underneath. A little puff of flame came up through the fire but nothing disruptive, the audience didn't notice a thing.

That however is just how I do it, your mileage may vary.

Frosty The Lucky.

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