Blown Burner

[brs]

any one using Jymm Hoffman style blown burner? I have been looking and studying all types of burners and this one looks the best for what I want to do. Want to build a Mankel type forge for odd shapes and use firebricks to close the sides when not needed

[Dave Hammer]

Jymm Hoffman's style of blown burner forges are outstanding. I have seen them in action. I like to make my own forges, or I would probably have bought one of his.

If you are still considering different types of burners or configurations... You might consider this...

I have made several types of propane forges, and have settled on the design shown below. This one has a heavy body (large oxygen tank), but could be made from lighter material. Although this particular forge has legs, I now weld a piece of "C" channel on the bottom so the forge could sit on a platform. Before I weld the channel on the bottom, I cut a circle out of the center of the channel on the bottom large enough to be able to weld half of a 1" pipe coupler on the bottom of the forge so I can put the forge on a pipe stand (shown). I weld "C" channel on each end to hold the soft brick I use for enclosing it. I cut out a slot on one side and weld on a shelf wide enough to hold a soft brick to close in the front when I don't want it open.

This particular forge has a single atmospheric burner (others I have use multiple burners). Jymm's style of a blown burner could be used if you wanted to. I have forge welded and made damascus billets in this type of forge with an atmospheric burner. I use Plastek 85 (ANH industries, I think) for the floor (impervious to flux).

I use a quick_connect for my propane hose attachment. If you choose to do this, be sure to get a quick_connect with an O-ring that will stand up to propane gas (nurile?). I buy my quick_connects at a shop that makes hydraulic hoses.

I use a 60 PSI regulator cranked all the way up, with an ALCON needle_valve to control the volume of propane (as opposed to limiting pressure). A partial turn controls the flow down or up.

This forge has an eight inch diameter body, with one inch of kaowool put all the way around (I use hi-temp wire to hold the kaowool up above the opening), then put in the floor, then put in another inch of koawool from floor around to opening.

The soft brick must be considered a consumable and will occasionally need to be replaced. Soft brick can be cut easily with a regular handsaw. I put the channel on the forge for the firebrick because I like putting my forges on simple pipe pedestals I can roll around in my shop.

Edited December 1, 2009 by djhammerd

[brs]

Thanks for the ideas I was thinking of a square type 18in X 10in X 4in out of castable or brick with a ceramic coating for the top and back wall and with bricks like yours for the sides and front The plastech 85 would be good on the floor What about burner placement I say Mr Hoffman's come in from the side

[Dave Hammer]

An eighteen inch forge will need at least two burners. Three small ones might even be better. You might have to experiment with burner size. Too much burner is not a good idea. With that short height, I would just put them in from the top (a little toward the back) straight down. Be sure the burner tips are up from the ceiling 3/4 to one inch or so (or they will burn up quickly). If you use brick, use soft firebrick. Hard brick will work, but it will take a long time to heat enough to do anything.

[Jymm Hoffman]

To get a more even heated chamber, I recommend one of my burner tips every 6 inches. It depends on which side of the chamber the burner tips enter and the size of the blower, etc will also affect the evenness. My first blown system was much larger with 2 burner tips coming in on the narrow side. It worked fine but was also much larger than needed for most of my work, and much more costly to operate in comparison to my smaller systems. It used at least 1 1/2 gallons of propane an hour. My smaller systems use about 1/2 gallon per hour for the 2 burners with a 12 inch long shell and about 3/4 gallon with an 18 inch shell. While it is not necessary, I prefer a curved top to help with a circular flow of the flame. I believe it helps get a more thorough burn of the fuel and a more even heat.

These are the only forges I use in my shop, the ones I build. Off to build another one for my Saturday class.

[brs]

Thanks for the info and the pics It give me a closer look at the burner that I had seen in your post on coal vs gas. I see your burner comes in on the side . Is this better than in from the top?

[Jymm Hoffman]

I don't know if the burn out rate is any better or worse in regards to burner placement. The definite advantage is flexibility in changing the system or repairs. With it in the bottom half, you can take the top half off to repair or even enlarge. With my first (much less efficient) system the top was one solid piece of castable over blanket. If I needed a larger forge, I just lifted the top off an piled up brick. This was the system that used about 1 1/2 gallons of propane per hour and took about 45 minutes to get up to welding temperature. With the smaller clam shell systems, welding temps are achieved in about 15 minutes.

I have also switched sources and no longer us the Rampack 85. I am now buying form Dixie Refractory Sales and Service. The salesmen puts in an order for me with another large batch and saves me huge amounts. With UPS shipping costs, it is still less than 1/2 what I have to pay for Rampack 85 locally. I am now coating the entire system with Thermogen 60, making a hard shell interior. Much less damage do to me banging up against the walls and working very nicely. If you send me a pm I will give you the email contact information.

I will also try to remember to take some photos prior to closing up the recent forge.

[Mills]

Jymm I would be interested in knowing more of this source. Could you email me as well?
 

[brs]

Thanks Jymm the pictures help alot and pm sent

[bikecopXXX]

I was going down the road of building an atmospheric burner, but Jymm has talked (typed) me into trying a blown burner first.  As a first iteration i will use a hair dryer.  which raises the question:  is there any significant advantage to using the heat+blower vs blower alone?    seems like a no brainer that heat+blower would be better, but it might be insignificant.  I plan to try it both ways. 

 

thx

Mike

[Frosty]

NO, using a heated blower makes no significant difference except your electric bill. If you want a recuperative forge it needs to be designed from the start to exchange exhaust heat to intake air.

 

I've thought about shaping the flame by making the burner nozzles flare like yours Jymm or making a ribbon burner but it won't work with a naturally aspirated burner, gotta be a gun.

 

Do you have any pics of it burning?

 

Frosty The Lucky.

[bikecopXXX]

well i built it, but it is too ugly for photos.   It is similar to Jymm's photos above, but with one burner instead of 2, with the end mashed down to a square oval shape.  It uses a hair dryer blower, 1.5" pipe, a regulator from a turkey fryer, and it blows into a brick-stack forge ala zoeller.  

 

Performance:  from cold forge to yellow heat on a 1/2" square bar in 3.5 minutes.  better than i expected.  I will try to get it up to welding heat next. 

[Dodge]

What fuel? IIRC, (Jymm, please confirm or deny) Jymm says they will run on household low pressure natural gas. This is what I want to try :)

[bikecopXXX]

mine is propane.  so far have made a bodkin arrow point for my neighbor and a garyhuston-style cross for my wife.   slowly learning...

Hey Dodge, i used to live in Bellevue as a kid.  my dad was in the AF at Offutt.

[Dodge]

Small world, eh?

One of my future projects is to run gas out to the shop for an even future-er heater. I would be interested in trying Jymm's burner out on NG :)

[bikecopXXX]

i like the blown forge so far.  it's pretty simple, no mig tips, flared ends or any of that.  just pipe, pipe bushings, cheap regulator/hose, free hair dryer from the goodwill bag....  screw it all together and light it.   my regulator can go from lean (near blowout) to super rich (big yellow flames coming out both ends of the brick stack) , but i have only had my blower set on low so far.  I have the zoot-capri 3-speed pink blower so i need to push it up to 2 or 3 and crank up the gas and see what it will do.

 

I'm a little concerned that it will be a gas hog, but i'm still on my first 20 lb tank, so we'll see.   

 

if you can plumb in NG that would be very convenient.