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Post by Brendan Olszowy on Dec 27, 2007 6:28:44 GMT
Hi I want to do the heat treat and quench on my own swords after the abuse my braveheart copped at the Spring factory. Maybe I'll get an anvil and try some wrought iron work like Matt's. Here the plan I had in mind. I'm after feedback from any one with experience before I make it. I have an air pump ready. Its going to sit on a BBQ trolley for portability. Basically I would make a box out of mild steel, cut down at one end for overhanging. Then have a pipe with small jets to fan the coals. Is it best to sit them on the brickettes directly or on a rack? If I put a rack in it, a lid on it with a barbeque thermometer, and a little door over the end opening, could it be used as an oven for tempering? About 1 hour at 250 degrees C for tempering, right? Thanks for any help anyone can offer. Brendan
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Post by Matt993f.o.d on Dec 27, 2007 22:01:48 GMT
Hey Brenno!
One thing I would instantly suggest is cooling. You need a clever way of keeping the forge itself cool. That is if you plan to do the heat treat in it. If the forge is hot enough to get the metal you put in it to white heat, how are you going to stop it from melting itself?
The forges we used on our course were water cooled. They had a filthy great vat of water strapped to the back of them, which circulated in thick cast iron channels round the firepot by thermo-siphoning. As the water boiled around the blower (in the firepot) it rose up the channels as steam, to be replaced by cooler water running in from the vat. Sounds complex, is actually dead simple.
But I bet you thought of this already!
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Post by Brendan Olszowy on Dec 28, 2007 1:11:28 GMT
Sam has PM'd me and sugested lining it with mounded clay or mortar, and creating a pit - that should protect the steel. Also to only make it 2 ft long and move the blade back and forward, rather than try and heat the whole thing up evenly over 5 ft.
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Post by Deleted on Dec 28, 2007 1:37:31 GMT
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Post by Brendan Olszowy on Dec 28, 2007 2:40:57 GMT
Thats a great link thanks hastur. Karma.
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Post by Matt993f.o.d on Dec 28, 2007 14:21:37 GMT
That's a good idea. Much simpler, insulating rather than cooling directly.
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Post by Brendan Olszowy on Dec 28, 2007 15:43:05 GMT
Does anyone know if theres a difference between blowing across from the side, or blowing straight up, as in hasturs link. I though blowing across may save ash filling the holes.
The forge is slowly taking shape.
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Post by Deleted on Dec 28, 2007 16:34:57 GMT
Brenno, if you look on Mr Lively's you will notice the end cap, when and if the tuyere becomes clogged you unscrew that cap and let the blower blow all the ash and crap out then put the cap back on, i have run a forge like this you only need to do that maybe once an hour at most.
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Post by Brendan Olszowy on Dec 29, 2007 6:55:06 GMT
Sorted. I'm rockin now.
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Post by Deleted on Dec 29, 2007 6:58:31 GMT
For an HT forge the key is MUCH MUCH LESS air, forging temperatures are not needed to less air is a good thing, probably a 25 CFM fan froma computer is a good thing i would bet. You want to get to 1550F and not much higher, any higher and you grow the grains and have to normalise again, then ehat again for the HT.
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Post by Brendan Olszowy on Dec 29, 2007 7:18:11 GMT
My air pump throws heaps of air. I thought it would just heat up faster, and I'd keep the blade moving back and forward. How long do I want it to take to get to HT temp?
Could you please explain "grow the grains"?.
I suppose I can loosen or take off the end cap of the pipe to reduce the flow? Maybe I can have a large hole between the compressor and the flame jets, which I can block with a bolt when I want to forge, and open up when I want less blow for HT.
Thanks for the heads up Sam. Anything else you can suggest is always welcome.
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Post by Brendan Olszowy on Dec 29, 2007 10:41:19 GMT
Well I've been working for a couple of days, buying parts, beefing up the BBQ trolley with corner braces, cutting this drum, blah, blah, now I've just come in from laying the mortar, and here's what I came up with. Obviously I have a fire pit with some cooler refuges on the sides, and the rolled ends of the drum to run the blades back and forth along (haven't done second end yet). The mortar is standard grey mortar, but it says it's suitable for building Barbeques, so surely its ok. This will be primarily for heat treating at first, and then maybe I'll try forging some stuff later. I have an old compressor with a vertical output, which will sit on the shelf under the trolley. I will cut that down pipe to fit it. And its portable. Wadja's reckon?
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Post by Dan Davis on Dec 29, 2007 13:48:35 GMT
Brenno, An airbrush compressor is about what you will need for heat treating steel and if you can come up with a hand-cranked blower that is even better as it gives you very fine control of the fire. Sorry I missed the post up until now; I've been busy with year-end accounting crapola
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Post by Deleted on Dec 29, 2007 17:06:23 GMT
You need the pipe to site in more of a valley, with 3 or 4 inch high walls on either side as wide as the pipe exposed on the bottom and about 6-7 inches wide at the top. Charcoal likes to be focused over the air source.
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Post by Deleted on Dec 30, 2007 0:23:13 GMT
He could do that with fire proof brick,yes?
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Post by Deleted on Dec 30, 2007 4:36:35 GMT
Yes line the edges of the channel with brick.
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Post by Brendan Olszowy on Dec 31, 2007 17:32:24 GMT
I did line the channel with brick. I ran the tuyere with the end cap off to reduce the blow, though it was still plenty. Problem being that it was far hotter at the near end of the forge / tuyere, and too cool at the far end. I couldn't heat it evenly, I managed to get about 6" of blade hot then but the time I moved along the other bit got cold. So my forge was a failure. It would be fine for actual forging small jobs, or for heat treating knives or daggers. But not enough for the sword.
Needless to say I abandoned it before overheating or trying to quench the blade. I'll visit the spring shop I think. But it has me keen on doing some Knives, Seax and Dirks, as its satisfying to heat treat it myself.
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Post by Deleted on Dec 31, 2007 18:40:15 GMT
What size where the holes you drilled? This is an easy fix brenno, try running it with the cap on the end. The pressure is only enough to come up through the first holes but because the end is capped the end holes don't work, not enough pressure to get down there and go up. You air source should be controlled and able to be dimmed.
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Post by Brendan Olszowy on Jan 1, 2008 2:06:40 GMT
The holes are 5.5mm, and there are 13 of them. Which basically adds up to the area of the Venturi of the blower - 23mm. The problem is the blower blows nearly like a vacuum cleaner, and is not adjustable unfortunately. If I put the end cap on it would blow the ashes sky high, lol.
You're right, I do need to be able to dim it down, I wonder if a dimmer switch would do it?
BTW have a Karma Sam for being so helpful with my projects.
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Post by Deleted on Jan 1, 2008 4:30:42 GMT
See if you can find a variac at a surplus store.
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