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I Forge Iron

Gas forge questions


MickSCollins

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I'm thinking about building me a gas forge, but I want to get a good idea of what I'm looking at in terms of fuel consumption and efficiency.

What are the dimensions of your forge?
How many burners do you use?
What PSI do you forge at, and if you weld, what do you take it up to?
What size and how long does a bottle of propane typically last you?
How long does it take your forge to get up to temp?
Is it naturally aspirated or blown?

If there's anything else that could be considered pertinent, I'd be much obliged if you shared it.

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I have to gas forges one I use for shoeing horses and the other for knife making. My shoeing forge is a NC Whisper Mamma, I am not very fond of this forge at all but it was expensive so I use it. It is a venturi burner forge and just heating shoes I have to run it at 11psi. My knife making forge is a blown forge it is 18" long and has a 7" ID in 15 minutes it is up to temp. I used a 3000

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Before you worry too much about efficiency, you need to decide what you are going to be heating in your forge.

The size, shape, and number of burners of the gas forge you build should be determined by what you intend to forge. If you are going to be making small stuff, a single burner (1/2" aspirated), 6" OD tube (maybe 8" long), lined with thermal blanket (and coated) will probably do the job.

If you are going to do heavy larger work, the forge would need to be bigger, with more, and larger burners. With aspirated forges, the number of burners is determined by the internal measurement (cubic inches) of the forge. If I recall, it's one 3/4" burner for each 320 cubic inches.

You obtain efficiency by using the right size forge for the job, and having the ability to adjust the pressure of the propane and the amount of air that goes in with it.

How much propane pressure you need varies with the size of the pipe, orfice, and whether you use aspirated or blown.

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I have to gas forges one I use for shoeing horses and the other for knife making. My shoeing forge is a NC Whisper Mamma, I am not very fond of this forge at all but it was expensive so I use it. It is a venturi burner forge and just heating shoes I have to run it at 11psi. My knife making forge is a blown forge it is 18" long and has a 7" ID in 15 minutes it is up to temp. I used a 3000
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What are the dimensions of your forge?
It varies. The top is 10" x 15" with the front opening 1 1/2" I mounted it on a scissors jack and can raise it up to accommodate larger pieces. I raise it up and put fire brick around the side and back then lower it onto the bricks.
How many burners do you use?
One, I built in a spot for a second but never needed it
What PSI do you forge at, and if you weld, what do you take it up to?
Depends what I working on. 2# to 30# I'm full time and when I'm making 1/2" tent stakes I put in 7 to 10 and turn the heat up.
What size and how long does a bottle of propane typically last you?
I use a 330 gal. tank. It lasts a year
How long does it take your forge to get up to temp?
When I'm working smaller stock it may take 3 min.
Is it naturally aspirated or blown?
Naturally aspirated I make the burners myself. But after reading about the blown burners gas useage I might try a blown one to see how it does

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MT: The scissor jack idea is ingenious, I may just have to borrow it.

I work a large range of stock and some very strange shapes, so the ability to change the volume of the forge to match is ideal.

I didn't figure that the type of insulation would make that big of a difference, but it does make sense.

As to not worrying about efficiency, if you don't have time to do it right the first time, you've got time to do it again. It's a lot easier and cheaper to change the shape of something before you've made it than after you got it all put together and working. If you can make something in such a way that it'll save you a lot of money and hassle trying to fix it if you didn't, shouldn't you?

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I have a 10" OD blown pipe forge about 16" long. 1 layer of 1" kaowool with a hard brick floor. It runs about 6-8 hours on a BBQ tank at a good high heat with the front "door" wide open for teaching a class.

I have a 9" OD 2 aspirated burners pile forge about 14" long that will run 8 hours on the same sized tank.

I have welded in the blown one when turned up; but have not tried it in the aspirated. I still use coal for my billet welding.

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