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I Forge Iron

forge temperatures?

Dave Budd

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I've finally got around to building myself a proper gas forge and gave it a first run today. :) I made use of the materials i had to hand, so the inside of it may be a bit larger than most of the forges I've seen (internally it's 10" diameter and 14" long). The burner I've used is a venturie sold for pottery kilns and the like on Ebay

Out of curiosity I put a thermocouple in to watch the temperature rising steadily and remain pretty stable whilst I knocked a few bits out. I had it settling around the 1170C mark whilst running the gas at 0.5 bar.

This is the first time I have used a gas forge of any sort for more than a few minutes (my previous pile of bricks+duff burner gasser was only any good for heat treating, not forging with). So I have no idea what to expect of it.

So, I was wondering. What sort of temperature and pressure do people normally run their forges at when forging. Then how about when welding? I've not tried welding in it yet (I'm going to put a cast floor in first) but I'm sure it will do it.

I'll get some paint on it and put some pics up soon hopefully ;) Feels strange joning the 21st century and forging with gas. Also not grit in my hair after a day of forging; what's that all about? :lol:

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it sounds like you have got it about right .. might increase the pressure a bit to get a little more heat out of it .i take it that you are useing a burner that sucks air from outside the forge . i prefer the blower type forges myself as they are easyier to adjust . forge welding is a bit different with a gas forge might want to build a smaller one for that use . the big difference is a gas forge dosnt overheat it barely gets to forge welding temp and the visual look is quite different from coal/charcoal.i have used a gas forge to weld i prefer to use coal/coke tho as i find it much easyier. if your going to weld with gas many guys use a smaller seperate forge with more insulation . the smaller dimentions inside combined with the extra insulation brings the temp up enuf to help . also fluxes tend to stick to the forge and make a mess that eventually ruins the forge lineing . the benefits of gas is the nice even heat without the smoke and ash . also it dosnt overheat usually so if you put 10 rods in it and start forgeing and are not watching it you wont end up burning up the last two(at least usually) ! good luck and have fun!

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Note that the typical gauges used for these forges ARE NOT ACCURATE! So comparing pressures between two different ones is rather useless unless you have calibrated your gauges right before the test.

What the gauge does is allows you to come back to a set point you know works for *your* system easily and you still may need to tweak it by ear and eye as things warm up.

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I now realise that each burner is unique and the gauges are also. so it's all only relative to itself :) That's fine, as you say it gives me a reference point to turn the dial to ;)

Just getting to know this new beasty and developing a new way of working I guess. I had some Anglo Saxon chain to make yesterday, so having the ability to keep half a dozen bits in the fire simultaneously was a real bonus. As was the fact that I could work on delicate things like a saw blade without risking bending or burning like I would be in the coke forge. BUT I couldn't get the sickle I was making today in there, so I was glad of the bottom blast solid fuel forge too B)

just gotta see how it copes with trying to weld in it next! Oh and see how long the 47kg bottle of gas will last. I'm told it is cheaper than coke and does have other benefits (less dust, corrosive xxxx in the air, no need for electricity, no clinker, etc) but a 47kg bottle of gas is a pain to move about compared to a few 25kg sacks of coke in a wheel barrow (I have to man handle fuel 300yds from the road to the workshop)

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  • 1 month later...

Without seeing a photo of the venturi/burner I couldn't say for sure, but my vernturi burner will handle pressures up to .8 bar (12 psi) without producing an oxidizing flame and will get up to welding heat at the higher pressures. But it's not just the burner that makes the interior of the forge hot. The lining of the forge can contribute significantly to the maximum heat obtainable. Ed Caffery (aka the Montana Bladesmith) says that he has acheived and increase of 400 degees Farenheit by lining the interior with ITC100. I lined my forges (on top of the ceramic wool insulation) with a combination of high temp furnace cement (3000 degree F) and ITC100. While I don't know how much of the increase in heat is attributable to the lining I do know that it was significant. The ITC100 reflects the heat from the lining back into the interior.

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