ka-tet Posted August 22, 2018 Share Posted August 22, 2018 24 inch long air compressor tank 2 - 3/4 t-rex burners 2 inch kaowool covered/sealed with mizzou castable slathered on itc-100 high temp temp probe I can get to about 2200F (according to probe) but it definitely takes a while, and about 16 psi to achieve. I'm wondering if my burners aren't quite tuned properly. The dragon's breath is mostly blue, which I assume means it needs more air, but i'm running it with the chokes almost wide open. Ideas? Comments? helpful critiques? harsh critique? I'll take them all. Quote Link to comment Share on other sites More sharing options...
Buzzkill Posted August 22, 2018 Share Posted August 22, 2018 If you're getting to 2200 degrees F you probably have far more right than wrong. That's a pretty long forge though. Have you calculated the volume of the forge chamber? My rough guesstimate based on the soda can for reference is that it's just a little under 700 cubic inches. If it's over 700 cubic inches and those are 3/4 inch diameter burners you are probably about to the limit of what those burners can do for you. Are you doing long twists or something similar which needs long pieces of stock heated up at once? I can't help thinking that I'm glad it's you paying for the propane rather than me. I'm not familiar with those burners so I won't comment any more on them. I like your gas supply system and idle circuit with one exception. I like to put the regulator directly on the fuel cylinder so that there are no hoses/lines that contain full fuel pressure. Since you're using hose that has protective braiding and copper lines the chance of burning or melting through a high pressure line is much less than other options though. You may still want to add another ball valve at the fuel cylinder for quick shut off in case of emergency if you're going to leave the regulator as you have it. If you are concerned about following regulations you may want to look up where your cylinder should be while in use. Quote Link to comment Share on other sites More sharing options...
ka-tet Posted August 22, 2018 Author Share Posted August 22, 2018 Thank you for taking the time to comment hg. I really appreciate it. I haven't measured it directly yey but I'd hazard to say it is about 700 as you guessed. I've been thinking and looking for a good solution to plug the back and reduce the size when not needed. My goal with it is to (eventually) try my hand at some longer blades and swords. So I built it knowing that was a long term goal. I don't want to just stuff the back with kaowool cause fibers /bad but I'd love any suggestions for a temporary plug. Was going to put a shelf on the back too so I could at least stack a brick there to close it off but haven't had time yet. Quote Link to comment Share on other sites More sharing options...
Buzzkill Posted August 22, 2018 Share Posted August 22, 2018 Well, even if you plan to forge a 50 inch long sword you'll only want to heat up about 6 inches or so of steel at a time. If you're using a hand hammer that's about all most of us can work before the steel needs to go back into the forge for another heat. Continually reheating the steel can cause decarburization (lowering the carbon content) in the steel and possibly cause excessive grain growth. So, the more you unnecessarily heat up your steel, the more you risk a weaker blade or one that won't harden well when quenched. Only when it comes time to quench is it desirable to have a long forge, and there are other ways of bringing the blade up to temperature for quenching. As for plugging off part of the forge that might be tricky unless you have uniform dimensions from the the opening to the baffle point. If you do then you could cut some insulating fire brick to about the right size to block off a portion of the forge. However, those bricks are fairly fragile and repeated heating/cooling cycles tend to make them a bit on the crumbly side. You'd also probably want to cut a pass-through hole in the baffle for longer stock. Based on the pictures I'm seeing this would be fairly difficult to do well and you'd likely destroy the brick when/if you wanted to remove it later. After my first forge, which was way too large, I've tended to try to go as small as I reasonably can. That helps keep the heat down when I'm working and it definitely decreases the cost of propane. The last 3 builds haven't exceeded 12 inches in length, and the current one is about 9 inches long inside. The longest blade I forged was over 30 inches, but that was a prop for a school play that wasn't heat treated. Still the forging was mostly the same as it would have been for a sword that could actually be used as a weapon. Quote Link to comment Share on other sites More sharing options...
ka-tet Posted August 23, 2018 Author Share Posted August 23, 2018 (edited) So basically it is just to xxxx big. What if I put in a small pass thru at floor level, then filled in the back 4 to 5 inches with mizzou? Effectively reducing the inside capacity by leaving a pass thru. I measured and is about 600 cubic inches total. Inside is 20 inches long. 7 inches high. And 4 to 5 inches high (not uniform). Edited August 23, 2018 by Mod34 Edited for inappropriate language Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted August 23, 2018 Share Posted August 23, 2018 He forgot scale losses too. a much smaller much cheaper to run forge with a good pass through out the back will do for eveything up to a zweihander---except for heat treating. And sizing your general forge for heat treating is rather like buying a dump truck for your daily commute as a couple of times a year you need to get a load of gravel. Keep that one for when you have a big powerhammer and can work 16" in a heat! Quote Link to comment Share on other sites More sharing options...
Buzzkill Posted August 23, 2018 Share Posted August 23, 2018 This may sound a bit extreme, and you'd have to have the right equipment to do it well, but you might want to consider cutting it in two pieces midway between your burners. I haven't worked with mizzou, so I have no idea how hard it would be to do a clean cut through that stuff. If you were to succeed though you should be able to fairly easily mate the two halves back together if needed for a longer project. A couple fire bricks at the cut would let you create your desired opening. You could experiment and decide which version works better for you - burner closer to the back opening or the front opening depending on which end of the which half you wanted to use as your main opening. You'd probably want to apply some more rigidizer to the fiber blanket where the cut was made, but other than that you'd be more or less ready to go, assuming the mizzou lining were to stay intact. Maybe someone with experience using mizzou knows what is needed to make decent cuts without ruining the lining. I'm guessing it would quickly dull most saw blades, but a dull hacksaw, handsaw, or bandsaw blade used with low pressure might do the trick anyway. To reduce the volume enough for one burner, you'll need to drop the volume to about 350 cubic inches or less. If it were me I'd seriously consider cutting the forge in half, but to reduce the volume of that forge without cutting I'd contemplate something similar to what you described. I'd be more likely to use fiber blanket or insulating fire brick pieces for most of the "plug" and then coat those with the mizzou to lock in the fibers of the blanket and provide a good flame face. However, I have no idea how well fresh mizzou will bond to the same material that has already been cast and heat cured. You may want to experiment with small pieces outside the forge before going very far down that road. On the other hand, you can use what you've already built. It seems to get plenty hot and is reasonably well constructed. For pieces that are around 12 inches or so you can just put about half the piece in the chamber with the rest sticking out and reverse the stock as needed. The only real drawbacks to that are increased heat in the working area, potentially greater carbon monoxide and carbon dioxide output, and increased fuel consumption. Working pieces much longer than a foot is where you would be repeatedly heating steel that you didn't need to heat up. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted August 23, 2018 Share Posted August 23, 2018 Open your chokes completely. The photo shows your flame is reducing. Quote Link to comment Share on other sites More sharing options...
ka-tet Posted August 23, 2018 Author Share Posted August 23, 2018 The chokes are open completely, so I'm not sure how to get more oxygen in. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted August 23, 2018 Share Posted August 23, 2018 Okay, something odd is going on. The burner is easily capable of making a near perfect flame, and the proportions of burner to forge sizes look acceptable, so I would look for something off internally. I would look for something interfering with the flame. Run the burners out in the open air. You should be able to match the flames in the photos on the Hybrid burners site. If not, than you know you have a problem with one or more burners; if you can match the flames in the photos, you have a problem with the forge. Start there, and get back to us. Quote Link to comment Share on other sites More sharing options...
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