Why two bricks and not one?
Well, this is the main reason:
As you can see, it's much easier to make a forge in two parts than to accurately hollow one out through the front aperture. With a router and 3/4" round bit, I hollowed both sides out in record time. I could probably knock these forges out at the rate of one an hour to this standard. Cost so far is about £2.50...
But does it perform?
With such a small internal dimension (3"h x 2.5"w x 6.5"d)the start up time is about a minute. This is the initial heat from a basic MAPP gas hand-held venturi burner.
I have no external casing at this point because I have yet to coat the inside with ITC-100, seal it with refractory cement and then wrap chicken-wire or something similar round it.
It is really unsafe to run this way, but I just had to fire it up.
You can see below the second reason why I used two bricks; you get a slightly more generous cavity than with one brick and you can better manoevure your piece around the flame jet.
The third reason is that I get better insulation this way. I left exactly 1" of firebrick around all sides. Those are plastic WorkMate lugs holding it in place. At the end of my test runs, the top brick was pretty hot, but didn't burn my hand when I touched it (again, don't try this at home and if you do, don't blame me if something goes wrong).
Here it is with the lights down low. I am using vise-grips, which wouldn't be a good idea for rorging, but makes things easier when juggling a MAPP burner, piece of 5160 and a digital camera.
This image looks like I have the tip way too hot, but actually it's only about mid-red and ready for work. If I were forging, I'd want to soak it and work the jet around the billet to spread the heat. But you get the idea.
At this point, I figured I'd try different burners. I have quite a few to choose from. Besides the MAPP burner, I have a Oxy-Acetylene porta-pack, a forced air + LPG burner, a forced air + white spirits burner, a way OTT T-Rex burner... and this ... an ordinary butane-fired cigar lighter. I planned to use it for lighting the MAPP burner, but hey, why not give it a try?
It did OK, not nearly as impressive and the much more powerful MAPP gun, but it did get fairly warm in there.
At this point I stuck the test bar in.
And it did manage to get the heat up into the forgeable range. Clearly, I'd need a better burner than this, but it illustrates the efficiency of this forge.
I may as well finish it up with a shell, or at least a binding. I'd also like to see whether the ITC-100 has much effect, before I decide whether to shelve it as a curiosity, or put it to some use.













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Don't try to understand 'em, just rope, roll and brand 'em...
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