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I Forge Iron

Johnson forge re-hab idea


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There has been some discussion in other threads regarding flame location in a gas forge--with implication that coming up from the bottom would be the ideal location if possible.  That got me thinking about the old Johnson forge that I was going to "fix up".  My Johnson has 4 tuyeres, 3 of which can be shut off.  I need to re-do the refractory as well as the hearth fire bricks.  The gas is blown--being injected prior to hitting the fan impellers.

I was pondering if (to save gas and get better heat) I could convert this to a more conventional bottom-blown gas forge.  Using only a single tuyere, possibly converting the outlet to a ribbon burner--it seems possible.  Sorry the drawing is rough but hopefully it will elaborate on what I am thinking.  On the left is the current set-up where the tuyere basically blows into a "trench" where the flame impinges on the opposite wall.

 The drawing on the right is the modified version.  By blocking off the trench to about a foot long with removable fire brick, inserting a deflector for the gas and partially covering the trench with a kiln shelf (and support for that)--then adding a standard mailbox-shaped enclosure roughly 12-14 inches long --it seems I get the bottom blown more-conventional gas forge.  Far more suitable for normal use.

Drawing is a cross-section in case that's not clear

Thoughts?  Happy to clarify if the drawing is too rough to understand.568ee79683547_Forgeidea.JPG.e1a06f0ebe4c

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are High school welding shop has a Johnson forge just like that & A Pain to work with !!!

you have to use welder glove just to get @ steel - me not as bad, But the Kids not a good forge for a school 

to easy to get arm hairs burnt or worse

an idea I saw on the web was someone cut the front sheet metal piece off & instead of putting steel in from the top

they put it in from the front had better control that way & it looked like a good fix 

I have No Idea why those forges are design like they are ??? don't care for them much

they look like they would be great for plate heating I just never tried that yet ???

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Hay Thomas for doing what kind of industrial use ??? Heat treat ? or what ?

always wanted to know that -- still seams if a school has a forge its a Johnson trench forge

I tried for years to get the weld shop to buy a better forge !!! finely just gave up :(

just didn't want to spend around $700.-- or so woun't let me modify forge witch I can understand that 

so they use as is with short tongs :o You JUST can't fix dumb

BUT THANK GOD !!!!!!!!!!!  we still have shops class here !!!!!!1

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The trench forges were for heating the ends of bars---line up a bunch of them and walk down the line doing whatever your company did with them refreshing them as they get used.  (good process would be to support a continuous cycle)  The "heat treat" Pedestal forges were used in the tool and die room/maintenance.

They got into schools as they were one of the few brands that would support all the safety features mandated.  (and back in the '60s and 70's there were just not a lot of "small" forge makers around like we have today for the hobby crowd.)


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I have a "gas" forge that was used in a tool and die shop for heat treating and the heat source was a White Gas Pump up Torch stuck through a hole in the side.  They never worked on anything big just tools for dies in a stamping company.  This was used up until 10 yrs, ago.  I don't have the torch and not sure what I'm going to do with  it but add to my museum. 

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