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I Forge Iron

Firepots


FlyingXS

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I have read a number of threads but they are so varied and cover so much I tend to go googly eyed and mushy brained. I figured it better to ask for opinion on my specific need.

 

Ok I'm starting to scrounge together parts to build a forge.    I have a piece of a very "I" beam (Steel Girder).  Laying on it's side it has base for the forge of 600 x 860mm @ 10mm thick.  Along the 860mm sides it has a flange extending up and down from the forge base equally of 228mm, so there will be a 104mm, wall to the top of the forge. This is 14mm thick.

 

The plan is to fit removable or hinged ends to the short sides at the top and apply the same design to some smaller cut outs to allow for long items to pass through on the long sides.

 

So my main concern is  what to do about a firepot??  Since I am still getting some welding gear together to learn stick welding I was thinking to use a brake drum I have at hand it is 125mm deep (5") and has an internal dia. at the top of 320mm.

 

What I would like to know before I cut a hole in the girder and am stuck with it, is is there a benefit to a fabricated firepot to a brake drum, or what are the pros and cons??

 

Also why do firepotes have a raised lip around them rather then being flush or fitted below the base of the forge??

 

 

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Assuming you'll run a larger firepot in the future (which is entirely likely), you'll just have to recut it to fit. The I beam is gonna last a lifetime. But I would build it where it intends to live, as the weight in this case is gonna wind up leaving you with back problems like me. :) most firepots you buy are 12" or bigger. So don't fret over an 8" or whatever hole. Especially if you own a welder.

Fabricated firepot is a good idea once you know what you want. Brake drum is a cheap easy way to figure out what you would change to make it better. My first forge was made from a round plow disk. It taught me beyond any doubt that a deep fire with less air was far superior to a shallow fire with lots of air.

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If you have not read it already, read the >link click here

 

Look at the 55 Forge.  It costs very little or nothing and is quick and easy to build. Once you put a fire in the 55 forge, most of your questions will be answered within a few hours.

 

4sd307.jpg

 

This is the side blast version of the 55 Forge. Just lay an air pipe into the fuel.

 

You will need to put the steel about 2/3 to 3/4 up toward the top of the fire ball. This will dictate the dimensions of your forge.

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That hunk of I beam is overkill in my opinion, you don't need such a heavyweight forge table, I think you'd be better off saving that for something else at a later date.

 

Without knowing what materials you already have or what you can scrounge it's hard to know what to suggest, so sticking to generalised advice - if you're not very experienced at welding for the minute I'd stick to something like the 55 Forge and fabricate your own setup at a later date once you've got a feel for how much size you need.

 

Just to give you food for thought when you do fabricate you're own setup and how much you can achieve with a relatively little forge - I fabricated this little forge out of a chunk of box section I cut up to make the firepot (approx 30cm long and 10cm deep) along with some box section legs and extra bits of angle iron. It was a thankyou present to a guy who came and helped me out for a couple weeks when I was preparing for a big 3 day fair. I use a similar size forge for demonstrations and I find it very useable. Note the sliding gate at the end to allow longer pieces to be passed through, (It's all fully welded underneath, the top welds are just kinda long tack welds).

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You don't need a fire pot at all.  Many professional forges back in the day were made with a flat bottom and they were used in industry, so they weren't just some gimmick.  My first coal forge was flat-bottomed and worked fantastically.  I never needed a fire pot and I was working stock up to an inch thick.

 

Get a flat table made from thick sheet, maybe even some quarter-inch if you can find it, and place a hole just off center so you have plenty of space on the side for fuel and tools to sit.  Below the hole you attach your air supply.  Over the hole you put a grate.  Go to forging.

 

Get a couple of regular bricks to use as moveable walls so you can build up your fire.  Use a watering can to control the spread of the heat.  Forge stuff.

 

It really is that simple.

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I know the beam is probably over kill but it is almost the exact rectangular dimension of the forge I am learning on.  The plan was to cut in little windows in the walls like Joel has on his above in line with the fire pot.  Joel how does the sliding gate work?

 

 

I have a nice lump of Duraflex 4145 at 70kg for an anvil.  I have also a striking anvil I forged some hardie holes in that is just waiting for me to get a welding mask and attempt to assemble as a first welding project.

 

 

Vaughn, with a flat bottom forge, Am I correct in understanding you still use the bricks as a firepot, just a flexible one?  With no bricks you need to pile your coke much higher to get the steel to sit in the top ⅓ of the fireball?

 

 

What I am thinking is I have the base of a 44Gal drum here I might drop the brake drum in that, build the ash dump and fit the blower all up test it and if happy how those parts work. Later I can transfer them to the beam if I still feel the need.

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I have found that the forge table is just that, a table. It holds coal/coke and tools. The fire is contained in whatever your are using for a fire pot.

If you are not planning on moving the forge you can make the table from whatever weight material you desire, even masonry. The heart of any forge is the pot and tuyere.

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While your I beam will work just fine for a forge a plain old flat table will be more flexible in use. There's nothing wrong with using a fire pot, thousands of fine professional smiths did and do.

 

If you decide to use the brake drum cut a hole so it drops into the I beam's flange so it rests on the rim. That'll make a lip around the drum about maybe an inch or 2-3 cm. A forge like this will let you work some nice long pieces though it will limit the size scrolls gates, etc. you can work easily to whatever width fits in the I beam's flanges.

 

I don't burn coal but have a few coal forges my "big" forge is just a 14ga. steel table top with a grate for the air blast. The table top is covered in salvaged fire brick that came from relining the coal furnaces in the power plant up north near Fairbanks. The "fire pot" is the space around the air grate about 2 fire bricks worth.That makes it about 2 1/2" deep and 9" sq. though I remember cutting brick so it's actually a little smaller but I don't remember exactly and don't feel like going out and measuring. Exact size isn't important anyway. I adjust the fire's size by arranging firebrick around the nest. That's it, easy greasy, fast simple and it works a treat.

 

The air supply is old 3", around 7.6 cm. truck exhaust pipe with a flap cap for the ash dump and 2" T welded in about 3" down from the air grate to hook up to the blower. Once again fast and dirty, easy greasy. I have a pretty complete set of hole saws so those are what I used to make the bolt flange that attaches to the forge table under the air grate and made both the hole in the 3" exhaust pipe and formed the 2" where it welds to the 3". The 2" is close enough to the bolt flange I was able to mig it together before migging the flange on.

 

It's ALL fast easy, eyeball measured and it works a treat when I need to teach students to use coal or charcoal. Most of the kids have researched how hard it is to get good coal here and most don't want the hassle of making a retort so they're going with a propane forge.

 

Frosty The Lucky.

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Vaughn, with a flat bottom forge, Am I correct in understanding you still use the bricks as a firepot, just a flexible one?  With no bricks you need to pile your coke much higher to get the steel to sit in the top ⅓ of the fireball?

XS, that's the basic gist of it.

 

The bricks allow you to shape and control the fire, which is what the fire pot is doing.   The difference is that you can move the bricks when you need a bigger/smaller/longer fire.  

 

The riveting forges that you see for sale everywhere are flat-bottomed and work a treat for heating small stock.  With a larger table to work with, a flat-bottomed forges can accommodate a fire of just about any size.

 

As someone new to the world of smithing, you're not going to be working on really heaving stock, or doing production-level quantities, so you don't need much in the way of a forge.  Keep it as simple as possible and you'll be pounding hot iron before you know it!

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