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I Forge Iron

Intro and Side Draft Chimney question

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This post is my first, so a bit of an introduction to begin with (sorry in advance for rambling). I am in NE Arkansas and developed an obsession with forging just about 3 weeks ago. In that time I built my forge (from scrap materials), acquired an ASO and luckily an actual anvil, a few hammers and have forged every day except 1 for about 23 days now. My forge has been tweaked a number of times since and now works quite well for me. My anvil has gone from mounted on a table to finally a stand, a post vice has been added, as well as a 2 lb cross peen and a 2 lb rounding hammer I “made” by modifying an engineering hammer, its fast becoming a favorite.


I have included some pictures to show the progression of my current shop, a few of the items and tools I have made, and my forge. One of the pictures is of “a knife shaped object” my 13 y/o son and I made together. 1st attempt for either of us to make a knife and his first time to forge anything, so its one of my favorites, although not quite one of my best : ) .  One of the more practical for me is a rod holder for my boat, just in case it was obvious what it was. You will probably recognize some of the other items from anvil fire projects.






















I know local resources are often brought up, so I will also let you know I have met a local smith, Glen Owen and have joined the AR Blacksmith Org and attending a meeting. Glen is he steward for the local chapter of the AR org. and has gone above and beyond to help me get started on the right foot. I owe him tremendously. He and I have also spoken about my question, but was just hoping for maybe some additional input from those that may have done this before.


Now for the question. I want to make a side draft chimney for my forge. I have been pricing large diameter pipe and it’s just out of  budget right now. I saw the Hoffi design which was a horizontal run of rectangular box then a vertical round chimney. I am currently thinking about going vertical straight through the roof, but was thinking about getting  sheets of 11 ga (1/8”) sheet and welding a 12” box for the chimney. My thought is to make it in sections that would slip together. I would create an insulated or double wall where it passes through the roof.


2 sheets would give me enough material for this (I need about 12 ft to clear the roof peak by about 3 ft) plus extra for flanges, hood , double wall section, etc.


Does this seem feasible? Any thoughts?


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Through the wall is 1/8" sheet metal. Chimney is galvanized tin from the lumber yard. I rolled a collar on the anvil and welded it to the box. I wrapped the tin around the collar/flange and pop riveted it together. It's not pretty or perfectly round, but has been just fine for about 5 years now. This was much cheaper than buying 12" pipe. 

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That definitely seems like a good option for a smith on a budget. It doesn't look like the tin has seen any heat. I have been trying to stay away from anything galvanized, not knowing what temperatures it can handle and still be safe. If I decide to go with a horizontal run before the pipe I will keep it in mind.

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It hadn't seen much heat at the time. Pictures were taken about 5 years ago. The side draft is now getting thin within 10" of the fire pot, but the chimney looks the same. There has been no color change that I can see. Galvanized would be cause for concern in the fire but there is an updraft on the chimney, and like I said no color change. Anyhow, everyone must do what they consider to be safe themselves. I personally have had no problems with this set up. 

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If it helps at all this is what I built for very cheap and it took all of an hour or so to do.. I'm in a make it work I'm broke as hell scenario.



basic layout of back/side walls, not all lines are cuts, some are bends


Front wall and flue opening


Section cut out


Sides bent and welded


This section I didnt photo before I cut, its a simple Z bent rectangular piece used to form a smoke shelf to aid in draft as well as the lower section raised to let me pull any lost fuel back into the fire.


bottom up shot before I added the face/top. You can see here where the shelf extends 3/4 the way to the front of the box, this shelf will cause a pressure vacuum as the hot air races past. 


Face section welded, I learned after my opening was too large but I can add doors or a new face section to reduce the opening that will allow less cold air from the side to be drawn in. 



I have added a small ring at the top to hold the flue pipe and an extension to the overhang to direct the fire into the opening, this is not needed once things get warmed up but helps before that.

When I rearranged my shop and forge the flue was no longer aligned with the hole in the roof/forge so I had to add this awkward double elbow. I have no insulator between the shed roof and shingles and have had no issues to date with heat and I have run full blast for eight plus hours. Each section of five foot flue pipe was about 9-10$ at lowes yea it should be something else but it works so I use it.


Hope these photos help! 

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Thanks for all the detailed pics Wesely. I see you went with round pipe for the chimney also.
Is there a reason no one uses a square tube for the chimney?

Round is likely to be easier to come by.

Eddie, I think you have to be the fastest smith in history! It usually takes people months or even years to build a collection like that. I waited several years to find an anvil! I'm very impressed!

Your forge looks excellent. Though I must say your anvil base looks a little bit big. Or at least awkward to work around. You'd be bar to get closer to the anvil if you mount it on a diagonal.

As for your chimney dilemma, have you tried sourcing material from your local scrap yard (junk yard??) you might be able to find what you need at a much better price compared to new stuff!

If not I see no reason why your current plan wouldn't work...

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Welcome aboard Eddie, glad to have you.


You and your son sure have been busy bees. You'll be happier with a more solid anvil stand unless it only LOOKS like it's on a steel table.


You don't see round stove pipe commercially because it isn't nearly as efficient, I don't know why but been told so by guys who do.


Frosty the Lucky.

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Thanks for the feedback.


I have definitely been fortunate to find things locally quite quickly, and that is thanks largely to Glenn, who I mentioned in my first post.


To comment on the anvil base, in some of the pics it was sitting on a table, in the latter pics its sitting on the stand I built. The stand is ~ 14" square, and is fill with crushed brick, its quite stable and size wise is working pretty well for me.


Since there seems to be no actual performance isues with going square, I think I am going to go that route. I can get 2 4x8 sheets for about $125 current prices, which will be enough for me. I can't find 12" round pipe for that price, and if I can do it, I'd rather build than buy anyway  : )  .

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