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forced air burner questions


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#1 j.van

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Posted 10 June 2013 - 12:21 AM

hey guys! Im looking to build my first gas forge and am wordering about a few things so here it goes: As of now, i am leaning toward building a forced air style burner and im not really sure what design to use (i dont own a welder which is why i am having trouble finding a design). Any ideas? Also (stupid question here), does the actual burning take place inside the burner or just outside the burner in the forge? Can i use pvc pipe for air intake or will it get enough heat to melt? and does anyone know where i can get some decent firebrick in the St.Paul/Minneapolis area?



#2 knots

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Posted 10 June 2013 - 08:17 AM

First thing - No Plastic please.  Although it is nice to have a welder it is not necessary to have one to build a gas forge.  

 

I built my first gas forge back ib the early 80's before internet offered  any information on the subject.   My solution was to use castable refractory for the forge body and 2" pipe and fittings  for the burner. The blower was Graingers acquired 4" surirrel cage type which I still use in two of my current forges.    So the answer to your question is Yes you can build  a forge with a blown burner without a welder .  The upside side is that there is a much simplier way to go.   When starting out it is a good idea to keep things as simple as you can.

 

There is a lot of information on gas forge builds in this forum so dig in and read as many of these threads as you can stand and then use the information gained decide how you want to go about building your forge.  In addition to this forum there are local blacksmithing groups that you should connect with .  Once connected to a group you will be able to see first hand what others have done.  

 

So far as fire brick is concerned what you really need is an insulating refractory material which can be had as insulation fire brick, fiber board, or fiber blanket.   So dig in search and read .   I suggest that you start with atmospheric burners.



#3 eseemann

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Posted 10 June 2013 - 09:16 AM

J,

 

The first one I built was welded, badly, and I used black pipe from Home Depot and a hair dryer for the blower. The next one was a one brick that I made from old cookie sheet and bent by hand in to place. I hold the forge together with a steel strap, nut and bolt. I use a Mag-Torch MT245C MAPP/Propane Heavy Duty Pencil Flame Burner Torch Tip and Mr. Heater 75,000 BTU 12-Foot Propane Hose Assembly from Amazon.com. Using the torch for the burner saves on propane and it will get hot enough to forge weld but the flux kills the brick. I have forged 5160 in this one brick rig.

 

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#4 Frosty

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Posted 10 June 2013 - 03:22 PM

Welcome aboard, glad to have you. Please put you're general location in the header, you may be pleasantly surprised at how many IFI guys live within visiting distance.

 

There are a number of considerations to regard in forge design. The most important for the forge itself is what size things are you going to be building. A one or two brick forge is extremely efficient but for limited sizes and shapes, they're used largely be bladesmiths.

 

"Pipe" forges refers to the shape (cylindrical) not the material it's made from. I recommend stainless steel stove pipe for a number of reasons. One of the best is all the tools you need to build one are tin snips or a hole saw, a hand drill is really handy but not a must and a pop rivet gun. You can buy everything but the refractory off the shelf where you find the stove pipe. The wall supports make excellent legs for instance.

 

Gun (blown) burners are easier to make and are easier to get tuned but do tie you to electrical, even if it's a 12v blower you need electric.

 

Finding refractory isn't as hard as it seems at first, a little finger walking in the Yellow pages will put you in contact faster than you'd think. HVAC, especially commercial HVAC outfits that do factories, etc. usually have large amounts of refractories of every type. Even if they don't sell retail they will put you in contact with someone who does.

 

Concrete and masonry suppliers will have fire brick of almost all types and furnace cement, fire clay, sometimes castable refractories, etc. If they don't have them, they'll know who does.

 

My last resort because of expense is a ceramic supplier, sure they have the stuff but it's usually a couple times what you can get it for from the guys who sell to the ceramics supply folk. they will have it or know who does.

 

Remember to bring note paper and a pen or two when walking the yellow pages. Once you've read through the info here, you'll be better able to decide the size and shape forge you want, can locate the materials and safety equipment to build and We'll be here ad happy to help.

 

Frosty The Lucky.


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#5 ThomasPowers

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Posted 10 June 2013 - 07:07 PM

You can make a blown burner without welding; they are dead simple look for an elbow with a much smaller sized opening for a third pipe coming out of it then section of pipe from blower to elbow large opening, Section of pipe elbow large opening to inside of forge and the small opening gets plumbed for gas---often with the inside end mashed down or capped and drilled on the side to make jets.


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#6 j.van

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Posted 15 June 2013 - 11:52 PM

You can make a blown burner without welding; they are dead simple look for an elbow with a much smaller sized opening for a third pipe coming out of it then section of pipe from blower to elbow large opening, Section of pipe elbow large opening to inside of forge and the small opening gets plumbed for gas---often with the inside end mashed down or capped and drilled on the side to make jets.

do i have to use an elbow? or can i use a "t"?



#7 Frosty

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Posted 16 June 2013 - 01:13 AM

Sure you can use a T but you'll want to run the air supply from the stem side and the gas jet in one limb the outlet to the forge out the other limb.

 

there are two very good reasons to run a forced air (Gun) burner around a 90* turn. First is it really aids mixing, propane is weird gas, it doesn't like mixing with air so you need to stir it with turbulence. The second reason is it won't burn back around a corner which only really counts when you shut it down or block the forge. Any gas forge needs enough exhaust venting to make room for the incoming air/fuel mix or it won't burn in the forge, it'll backfire then go out.

 

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#8 Dodge

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Posted 16 June 2013 - 10:26 PM

I threw this forge together from spare parts and a canabalized stand from my first gasser. The burner, essentially, required no welding except the flame holder, but I wasn't trying to build a "no-weld" burner. However, ALL of the parts for it can be purchased at even the poorest stocked hardward, H I center, or big box store

 

Attached File  med_Misc_005.jpg   42.19KB   3 downloads And it does get hot. Attached File  Forge 003.jpg   41.85KB   3 downloads I melted some 2300ยบ rated doors I added after that pic was taken :D


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#9 ThomasPowers

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Posted 17 June 2013 - 08:31 AM

The elbow helps create turbulent flow which mixes the gas and air better making for a more efficient burner


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