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I Forge Iron

Bathroom fan?


GIJosh

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Hi everyone,

I just recently joined the site and I'm a new blacksmith building my first forge. I've read a lot of threads here and elsewhere and of course watched many how-to YouTube videos on forge building.

I've settled on building a brake drum forge inside of a 55 gallon drum to forge inside of my garage. For safety reasons I will only be forging with my 2 car garage door wide open, as well as the side garage door. For a chimney I'm installing a 12" vent tube to the top of the barrel which will take smoke out of the window.

My question is, has anyone tried to setup a bathroom fan or something similar to suck the smoke out in a similar barrel forge configuration? With a 12"chimney is this just overkill?

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The type of blade a typical bathroom fan  uses can`t handle static pressure ie so  they are not designed to be ducted so you would have to keep the duct section short for it to work .A squirrel cage blade fan are designed to be ducted .

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I had thought about using a vent fan when i was initially starting to build my forge, and ended up not needing it. i was also concerned about ash and soot building up on it and killing the motor.

Pictures of what your trying to do would be a great help for others on here to understand what you are trying to do exactly.

 some things to think about are the air draw. once the vent tube warms up the air will be drawn out. 12" is a good size vent pipe. other questions are how big is the opening in the barrel? the bigger the opening the less draw. also think about how your routing the pipe. the more angles and sharper angles will hurt the draw as well as the longer the pipe between the angles since you said your venting out of a window. also the heigth of the pipe outside. it needs to extend at least 4' taller then the peak if the roof IIRC.(You Will want to check codes and such on that one) 

i found some good info when i was building mine on a site google beautifuliron, info under under forge and fire. 

so with pics or more info i think some others could help more. i wanted to vent out a window as well but it didnt work out for me with what i tried and ended up with 10" pipe going thraight up through the roof. it works great and if i had to do over again i think i'd only change to 12" pipe.

 

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16 hours ago, stan said:

The type of blade a typical bathroom fan  uses can`t handle static pressure ie so  they are not designed to be ducted so you would have to keep the duct section short for it to work .A squirrel cage blade fan are designed to be ducted .

Actually typical bathroom exhaust fans are designed to be ducted, just not with a whole lot of static pressure.  Typical bathroom exhaust fans run in the 50-140 CFM range and between 0.1 and 0.25 inches Water Gage of static pressure.  This pressure is fine for the typical backdraft damper and 20' of 6" diameter duct that is run from a toilet.

However, though a good bathroom exhaust fan is rated well for the high humidity bath exhaust it is not at all well suited for the heat, ash and sparks that might arise in a solid fuel forge exhaust stack.  Many bath fans have plastic components, including impellers.  I would never recommend using a bathroom cabinet fan for forge exhaust.  You might be able to use one as a forge air source, but there are many better options available.

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16 hours ago, latticino said:

Actually typical bathroom exhaust fans are designed to be ducted, just not with a whole lot of static pressure.  Typical bathroom exhaust fans run in the 50-140 CFM range and between 0.1 and 0.25 inches Water Gage of static pressure.  This pressure is fine for the typical backdraft damper and 20' of 6" diameter duct that is run from a toilet.

However, though a good bathroom exhaust fan is rated well for the high humidity bath exhaust it is not at all well suited for the heat, ash and sparks that might arise in a solid fuel forge exhaust stack.  Many bath fans have plastic components, including impellers.  I would never recommend using a bathroom cabinet fan for forge exhaust.  You might be able to use one as a forge air source, but there are many better options available.

Yeah I suppose it depends on what is meant by typical, over here would mean the ceiling installed exhaust fan  which are not meant to be ducted of course you can get the better ones that can be ducted.

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Here are some pics of the forge I'm building. Again, that's a 12" hole on the top that I intend to fit with a chimney pipe of some sort. After reading the responses I've decided to skip the exhaust fan and just forge outside until I can get my garage properly setup with a vertical chimney.

The forge isn't complete quite yet. I still want to weld a stand on, and I'm considering adding dual steel accordion shutter doors to the rectangular work entry to better control how much smoke escapes through the front.

 

Let me know what you guys think.

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Looks like a good start to me. I'd try it.  Once you get it set up and you start using it you will find things that work well or things that need tweaking or rethought.  The basics of what you have will work, And we always find ways to make it better.  I don't think you'll need the doors on the front as the smoke will rise and go out the top. As you said your going to try it outside first so I'd hold off on the doors for now.  Get it together, give it a go, and let us know how it worked for ya.  

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