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I Forge Iron

Optimal Cylinder Lenght help please.


CTBlades

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Good after noon folks, well morning if your Frosty. I am looking to build a gas/propane forge. I found a nice free piece of stainless steel tube 12" dia. by 24' long, 3/16' thickness. It needs to be cut to length as 24" is just way to long. Its going to be cut tomorrow (again for free, my favorite word lol) and I was looking for suggestions on the optimal length. My thought is 12". What say you keepers of the flame?

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I myself would go for two gassers 12" long. More than enugh. Failing that, two, one 8" and the other 16". Hand forging over 6" is hard, the 16" two burner would set idle much of the time, but when you need to normalize a longer blade, or heat a longer scroll you would have her. My proforge is abut that size, and for most things just two dang long. 

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I think the second option is better for you. As with solid fuel its pretty easy to make the fire smaller, not so much with gas, smaller forge is in order. 

You will do 90% of your work in the 8" deap forge. It will give you a 8x8 chamber with 2" insulation and 2" insulated brick doors (2" fabricated doors with 2" of ceramic wool works too. 

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2 hours ago, CTBlades said:

I know, a blow hole lol...

Oh, it is poor poise to offer ME such a whale of a straight line, I hope I don't sound too deep it isn't a breach. Now you really have me wondering, how well do you know a blow hole?

I like that size pipe MUCH better than the sq. pipe you were talking about this morning. Two options come to mind right off: Long with a movable back wall and multiple burners on individual valves. Oh heck get all 24' and go into business selling forges!

My preference would be two shorter chambers, I like two 12" ones. Wait for it, W-A-I-T . . . F-O-R . . . I-T . . . .  with removable back walls and an easy method for connecting them together. That way you have the best of 3 worlds.

The cut down forges don't have to be the same length by a long shot, 12+12 is the same as 16+8 so you can have a nice spread of forge sizes.

You'll want white bi metal jig saw blades and hole saws for making the ports and such. Stainless isn't so hard as it is chewy, don't hog the feed speed and make sure the cuttings clear it galls at the snap of a finger. I LOVE SS for forge shells it's a better IR reflector than mild steel so it's just another little bit of efficiency and it's shiny. Oooooh SHINY! ;)

Frosty The Lucky.

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1 hour ago, Frosty said:

removable back walls and an easy method for connecting them together. That way you have the best of 3 worlds.

The cut down forges don't have to be the same length by a long shot, 12+12 is the same as 16+8 so you can have a nice spread of forge sizes.

 

I like the idea of removable back walls and and easy coupling for a larger forge. Nice thinking. I think a 12" and an 8" will do as this piece has a couple holes at one end because it was actually slated for some other project but wasn't used. They would still both be shinny ;)

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13 minutes ago, CTBlades said:

I like the idea of removable back walls and and easy coupling for a larger forge. Nice thinking. I think a 12" and an 8" will do as this piece has a couple holes at one end because it was actually slated for some other project but wasn't used. They would still both be shinny ;)

You're going to cover any holes with refractory anyway, why give up 4" of good toolage? So as not to mar the shiny come up with sparkly bangledy doo dads you can make up creative stories about how they boost efficiency? :ph34r:

Frosty The Lucky.

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2 minutes ago, Frosty said:

You're going to cover any holes with refractory anyway, why give up 4" of good toolage? So as not to mar the shiny come up with sparkly bangledy doo dads you can make up creative stories about how they boost efficiency? :ph34r:

Frosty The Lucky.

Ok I'm just not even gonna touch that (give up 4") comment lol...

i was actually thinking I would use that for legs and handles so as to keep it as shiny as I can :)

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13 hours ago, Frosty said:

Oh, it is poor poise to offer ME such a whale of a straight line, I hope I don't sound too deep it isn't a breach. Now you really have me wondering, how well do you know a blow hole?

I knew you were going to go spouting off on that one.

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Since it is so thick, and because it is stainless, you well never have a better shot at using screw fittings, and keeping them functional in something that goes through regular thermal cycling.  Also, these two facets of your shell structure will facilitate installation of brass fittings on exterior hardware (ex. installation of burner ports; see Ron Riel's mini forge pages for further information). You have the oportunity to make this forge a show stopper, and to build it so that anything you feel dissatisfied about its construction can simply be unscrewed and changed out afterward.  BTW, two burners in a 12" long forge is optimal--if they are small ones (1/2" or less).

That is the positive spin version; I would get hold of a little helium tank and build the OPTIMAL design for a first forge first, and put any fancy forge design on the back burner for now. Of course, you can just call this a creative story about how to boost efficiency, and do whatever you like.  

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7 hours ago, Frosty said:

It did need baleen out a little.

Frosty The Lucky.

You have cod to be kidding me. I've about haddock with the tail end of this thread. It's really starting to flounder. Is there really any porpoise to it or are you guys just wanting to make me crabbie?

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56 minutes ago, JHCC said:

Just trying to make your forge more effishent.

Yes sir, just poking a little fun at Frosty. Anyway, I did a little calculating and with a 12"x12" cylinder lined with 2" wool and 1/2" kastolite 30 LS it comes out to 264 cu. in. (Both ends open but will have doors lined). This would indicate a one burner setup instead of a two burner according to what I've read. Why the suggestions of a two burner unit?

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Ayup, two burners makes more even heat in the forge. Having a little more burner than it needs is better than not enough you can turn them down. Two burners also gives you the option of running one if you need more localized heating, it doesn't work great but it has it's uses.

I don't know about you guys and puns, I figured you would've called fin by now but oh no you scaled it up. Do I need to go old school on ya?

Frosty The Lucky.

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Yea that has a lot to do with size and shape i believe but i dont know what the optimal shape would be but i would do two 3/4 burners and run them on the low end... but im in the more power crowd. But if you dont have a mutli tank or large propane tank(like me) two burners is a good way to freeze up a 20# tank if your in a cooler climate

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10 hours ago, TFT said:

Yea that has a lot to do with size and shape i believe but i dont know what the optimal shape would be but i would do two 3/4 burners and run them on the low end... but im in the more power crowd. But if you dont have a mutli tank or large propane tank(like me) two burners is a good way to freeze up a 20# tank if your in a cooler climate

There's such a thing as too much gun. In a 325cu/in chamber a single 3/4" is mid range. The only reason he's thinking about multiple burners is to even out the temp over a long relatively narrow chamber. Two 1/2" burners are still mid range with the same output as a single 3/4" but will heat more evenly. Putting two 3/4" burners in it will produce so much back pressure their performance will fall significantly.

I'm in the "It's better to have it and not need it than need it and not have it" camp but there comes a point beyond diminishing returns, the point when it's actually harmful to your goals. I've made that very mistake with burners and happily offer you the benefit of my mistakes.

Frosty The Lucky.

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