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I Forge Iron

Need some advice on gas forge build


Nathan Stanford

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I started smithing with a small coffee can forge (plaster and sand refractory) using a swirl tip blow torch tip.  I have decided to build a forge out of a helium tank and Kaowool.  My question is should I build my own burner or will my blow torch work.  I use it connected to a grill size propane tank.  Here is a picture of it so far.  Will be putting a door on the front.  Also should I line with refractory of some sort?

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No the volume of my first forge was about 2" diameter by about 5 in deep. Lol.  I wanted to make sure that I was going to actually take it up. (I did not forsee the level of 'obsession' as my wife calls it. Lol). I have been looking at burner builds for it.  I am seriously considering building the burner that Frosty has posted.  Seems to be a relatively simple burner to build.  I'm just not that good with the tap set and I am also not good at doing all that math to figure out what I need.  I'm sure I can manage the fabrication though.  What is the reason one would bring the burner in at an angle or straight down from the top?  I plan on making this my forge going forward so I want to make sure that I have all of the logistics figured out before going any further.  This is the best place that I have found to get advice so I hope I am not annoying anyone with questions that are possibly elementary.  Any assistance on the build is greatly appreciated.  Forge will just be used for small to medium sized knives and possibly some decorative projects.  I would really like to be able to forge weld and make damascus in the future with it as well.  Here are pictures of my first set up

First Forge

First forge.jpg

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The reason one would place the burner straight down from the top is that they wish to possibly increase the carbon monoxide content of the exhaust as hot gasses go up and so can get rerun through the burner spiking the CO production.  Placing it on the side allows it to swirl around the forge increasing the dwell time and helping with heat distribution. And hopefully offsetting the intake and exhaust enough to not re-run exhaust through the burner. Ventilation is MANDATORY with  a propane forge anyway.   Especially when knifemaking as we tend to run reducing anyway.

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The front of the forge being the ventilation?  And do you think that Frosty's burner would be a good choice for a forge like this one?  My plan is to coat the ceramic insulation with about 1/2" of refractory and then put a hinged door on the front with a hole for viewing/stock.  From what I have read, it seems that about 4"x4" opening would be ideal for this size forge.

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No! Ventilation is the removal of exhaust gasses and the replenishment of breathing air.  In my shop, 20'x30' with 10' walls and a peaked roof,  I have open gables and  generally have two 10'x10' roll up doors open for ventilation.  If you don't have ventilation it's cheaper and less of a problem to just breath your car's exhaust and skip the forge.

Yes I'm making a fuss about this; but the big problem with propane forges is that you can't see the toxic gas.  With a coal forge it's WHOA, I don't want to breathe that nasty stuff!  All forges that work by burning fuel produce carbon monoxide (unless you could get a hydrogen fueled forge...)   I suggest people in cold areas get a carbon monoxide meter AND USE IT as we tend to want to close up the shop and have a nice warm (and deadly!) shop.   Hot weather folks may have a shop that's just a roof and large fans blowing air around...

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Oh gotcha...Yeah when I start running this larger forge I will be more aware of ventilation.  My garage is about the same size as your work area.  I dont have big huge doors like yours just 2 car garage door.  So if i get a CO meter then i just open the door when it gets to a high level?  You are right opening the doors in the dead of winter in Iowa is not real condusive to wanting to work metal. lol  I open the walk in door from time to time but with the small forge I dont have any problem with the ventilation.

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Carbon Monoxide as well as being colourless, odorless and tasteless preferentially bonds to your blood in place of oxygen.  If you wait until the level is "too high" you've already been stockpiling it in your blood.  "In fresh air, it takes four to six hours for a victim of carbon monoxide poisoning to exhale about half of the inhaled carbon monoxide in their blood"

I would increase ventilation when you start the forge and if the CO level climbs increase it even more of LEAVE!  (Make sure it's not entering the house too.)   I know about the small forge---I used to run a 1 soft firebrick forge in my basement during the winter---of course that 100+ year old house had a basement so drafty there wasn't a problem.

 

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The nice thing is that my garage is not attached to my house.  I only spend 3-4 hrs in my garage at a time and I exit it several times during that time.  I was scared there for a minute that I was spending too much time in my poorly ventilated garage.  Looks like my forge will be around 275 cubic inches maybe a little smaller.  I'm just looking to build a cheap, efficient burner to be able to eventually get hot enough to forgeweld and do little projects as well.  Wayne, I love the hinge set up that you use on your forges.  I am going to adopt this design.  From what I have gathered I should be okay making a burner like what Frosty has posted prior and putting it at an angle on the side of the forge.

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No, Thomas; I'm afraid they aren't out of the woods with a straight hydrogen flame either; they only exchange the danger of CO for eye damage from ultra violet light; a little talked of problem with straight hydrogen torches. You see there aren't any carbon atoms to form carbon monoxide, but then they aren't their to filter the UV that high energy combustion creates, either:P Hydrogen flames are the only known hazard for UV production in modern industry short of an electric arc. Ain't science wonderful?

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I didn't say there were not *other* hazards; I said "All forges that work by burning fuel produce carbon monoxide (unless you could get a hydrogen fueled forge...) "   You could have mentioned the old broom trick with respect to hydrogen too; but what I was talking about was CO. 

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Did you search on Hydrogen  and broom? Figured if you knew about the UV you'd know the broom test...one of those oddball ways folks have come up with to deal with stuff low tech.  I'll ask my Pastor or his wife at Bible study tonight if they are taught it anymore as both are on the VFD.

As burning hydrogen is pretty much invisible: "Previously, firefighters responding to a hydrogen fire had to give the suspect area "the broom test" by carefully probing the suspect area with a corn straw broom to determine the presence and location of a fire. "  (from a NASA spinoff page on invisible flame imaging)

"The typical flame detector used in many hydrogen applications is the simple corn broom, where you hold a broom in front of you and if the broom catches fire, you stop moving forward. "  (Spartan Controls)

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I've used a hydrogen torch gas generator. Yes the gas is invisible until it's bubbled through a boric acid methanol to cool the flame and give it a green color.  I never heard of the UV damage associated with hydrogen.  They are great for platinum work.  

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