Harris Snyder Posted June 16, 2013 Share Posted June 16, 2013 Hey guys, I've switched to gas as my primary forge, but I'm going to make a little charcoal forge specifically for forge welding. Unfortunately I spend most of the year in the city, where gas is much more practical than charcoal for main forging work (and coal is basically out of the question), but my one burner gasser isn't quite powerful enough for forge welding. So I'd like to build a charcoal forge specifically for forge welding jobs. I'm going to be making the firepot out of refractory cement most likely, since i've got a bunch of it kicking around. Really what I'm wondering is what shape and size to make the firepot. Also, is a hand crank blower ideal for this application? I would reason that it would give the best control. Thanks everyone, Harris Quote Link to comment Share on other sites More sharing options...
VaughnT Posted June 17, 2013 Share Posted June 17, 2013 Why isn't your gasser getting hot enough for forge welding? All the pro's that use propane have forges that can forge weld, including making damascus....... so what are you doing different? Too large a chamber? No ITC100? Not enough burners? Too much air in the mix? You might need to change things up a bit, but there's certainly no reason to switch to charcoal or coal. Quote Link to comment Share on other sites More sharing options...
Harris Snyder Posted June 17, 2013 Author Share Posted June 17, 2013 No ITC, not enough burners. It's hardly an ideal forge, its what I could make in the city Thing is, I've got all the crap to make a charcoal forge staring me in the face, wheras ITC is expensive, and a second burner would either be different (if i made it myself) or be expensive if i bought another one of the same. Then theres the hassle factor... I know it is very doable and not even that big a deal, its just that a cement charcoal forge is so simple, and I'm tight on time for a few projects here. I don't mind having two setups.. I enjoy charcoal and gas equally. Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 17, 2013 Share Posted June 17, 2013 Vaughn: Harris bought a burner that isn't going to operate up to a normal home made 3/4" burner so it isn't enough for the forge volume. He'll get tired of it and we'll get him cooking properly after a while. <wink> Harris: Don't over think a charcoal forge, they're really simple things. It's easy to fall into the snare of having to use something just because you have it. We all do it, I still do it but I've become lazy enough not to be too stubborn about it. <grin> You can make a fine charcoal forge by lining a table with refractory clay. (HEY I didn't say you wouldn't be using the stuff did I) make a hole in the table to pass the tuyere, I like welded exhaust pipe but plumbing pipe works just fine, it's just more expensive. Lay a brake drum or rotor in the clay so the pipe lines up. Hook up a hair drier or hand crank blower if you find a deal on one. And you're ready to go to work. There are pictures in the forge section showing several different ways to make the air supply and forges from exquisitely simple to holy moley!!! complicated. What you'll need when it comes down to it is a fairly deep fire, charcoal doesn't consume oxy as fast as coal or coke does so you need more depth of fuel between the air grate and your steels. having plenty of room around the fire is really handy to keep fuel, lay tools and support longer work in the fire. With charcoal you don't really need an ash dump as it doesn't make clinker so an occasional hard blast of air will blow ash out of the works. Do that when the forge is COLD so as to NOT blow burning embers around the yard. (I didn't really NEED to say THAT did I?) Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Harris Snyder Posted June 17, 2013 Author Share Posted June 17, 2013 You don't think the 1" thermal art design burner is any good? I mean that forge is my first adventure into propane so what do i know. I figured at the time that it would probably be better. Maybe it's the forge, not the burner that's a problem. Though I did rework it a bit and put 2 inches of kaowool everywhere (not just the top), and used a thinner hearth. I got welding heat in a small patch under the burner. Have you heard anything negative about the burners from thermal art design before? It looks well made, so that's news to me. But like I said I know little about gas rigs. As for the charcoal fire pot, yeah a deep fire is what I was thinking, especially if it is specifically for welding. I'm thinking 9 inches square at the top and 8 inches deep... I'll make it an upside down pyramid shape, and build it into a table so I can have spare fuel, water, flux, tools, etc, all right there. Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 17, 2013 Share Posted June 17, 2013 No I haven't heard anything bad about the thermal Design burner except for your experience. My 1" burner will bring 700 cu/in to steel melting temp @ around 12psi and melt fire brick under the burner. I routinely weld in 300-350 cu/in with a 3/4" burner and it's melting the fire brick under it too. Two guys came over today and the three of us spent a few hours welding up some cable. Mine didn't take but I screwed it up, the forge was plenty hot. Your experiences are my only basis for that statement I made regarding your burner not being up to snuff. It should've burned the paint off the outside or scorched whatever's under it with that size burner in that small a forge chamber, in maybe the first 10-15 minutes. Don't sweat it, it just might need a little tweeking or something else might be the factor. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 17, 2013 Share Posted June 17, 2013 Did I miss where you explained what size work you were wanting to weld? If not then all I can say is that your forgepot should be between 3" and 6' long and 6" to 12' deep. Charcoal needs depth and a lot less air than coal; but does not gain too much with extra width other than fuel use. Weyger's book has a picture of a charcoal forge used in asia in it that has tall sloping sides to funnel charcoal down to the hot spot during use. Quote Link to comment Share on other sites More sharing options...
Harris Snyder Posted June 17, 2013 Author Share Posted June 17, 2013 No you didn't miss it I just forgot to clarify that point. I think the largest stuff I'd be welding in this forge would be damascus knife billets. I suppose you're right, more like 6" square at the top, and 12 inches deep probably makes more sense. I haven't heard of this Weyger's book, but I'll look it up, thanks. Frosty, well if that's the way it should be then I guess something isn't quite right. I'm going to play with the choke settings a bit more and maybe change the opening to the forge so its a bit more constricted. Actually, later on today I'll post a proper picture of the forge as it is now (like i said I made some adjustments).. Maybe It's my fault. Either way I'd like to look at the design of the burner you use! :) Harris Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 17, 2013 Share Posted June 17, 2013 Great, largest billet I have seen pictures of was over a ton, (Manfred Saschse's Damascus Steel book, the German edition). I weld billets of widely varrying sizes; including some where I have to wait to visit a friend with a LARGE forge and powerhammer Quote Link to comment Share on other sites More sharing options...
Harris Snyder Posted June 17, 2013 Author Share Posted June 17, 2013 "damascus knife billets" come on dude you have an idea of how big a knife billet is :) Main thing I needed to know was the depth anyways, thanks. Quote Link to comment Share on other sites More sharing options...
Frosty Posted June 17, 2013 Share Posted June 17, 2013 You can find my burner and several others in the gas forge section, If you need clarification, not a bit unusual if I'm describing something, let me know Ill clarify. <crossed fingered grin> A little tweeking and tuning is normal for gas burners, no matter how well packed, shipping can move stuff. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Harris Snyder Posted June 19, 2013 Author Share Posted June 19, 2013 Cool, I'll look around. I actually made some adjustments to the forge and it seems to be working better. Will post pics on the other thread tonight Quote Link to comment Share on other sites More sharing options...
DickyPitts Posted July 5, 2013 Share Posted July 5, 2013 I second what Frosty said about over thinking the charcoal forge. I also agree with wanting two set ups. I have tweaking to do on my gasser to get it up to welding temp (actually temp isn't the problem, It's plenty hot enough, but it makes scale in the fire and my most effective attempt at choking the burners consisted of a strip of duct tape partially obscuring the intake venturi's, anyway more work necessary and I haven't had time) I can make a forge weld work with a fire on the ground and a hair dryer, but no matter what flux I use, I can't weld in an oxidizing fire. grrr. I Love Charcoal!, in part because it's easy to localize your heat and in part because it's so "traditional". I once made a working "field expedient" forge in mexico with a pile of rock, some dirt mixed with ash and water to make it harden, a rusty pipe, some sheet tin for a wind catcher and a fan made of downed palm fronds. It didn't get to welding heat, but that's because I didn't have a proper bellows, blower or electricity to run a blow dryer. I also didn't have the patience to use the natural bellows contained in my rib cage...besides it makes you lightheaded. The charcoal was just laying around and I wanted to do a little forging. The anvil was a rock... I made several hooks, a poker, and a rake for the fire, and over all, just had a good time making such a primitive set up work. It's easy to get caught up in having the best tools for the job, but the truth is, that almost anything will work, otherwise our ancestors would never have gotten beyond flint shards and twisted bark. Good luck and happy forging. Quote Link to comment Share on other sites More sharing options...
Harris Snyder Posted July 5, 2013 Author Share Posted July 5, 2013 Yeah, its true about overthinking it. That said, I've had a lot of frustration over makeshift forges that devoured fuel and oxidized the steel, so I'm going to try to avoid those two problems this time around. Quote Link to comment Share on other sites More sharing options...
Frosty Posted July 6, 2013 Share Posted July 6, 2013 Harris: burning too much fuel and burning up the steel is a fire management problem and usually not specific to a forge type. Learning to understand how a fire is behaving is a learned skill and takes practice. I know Glenn has posted illustrations of the burn zones in a coal fire a few times and if you just deepen each zone it works the same for charcoal. A fire making scale means there's unconsumed oxy getting to the steel, nothing else will scale it up so there's no other answer. You can turn down the air but if it isn't making enough heat you just need more fuel between the air blast and the work. Dick's forge is scaling for exactly the same reason, there's unconsumed oxy getting to the work, it needs to be choked down some or the jet can be lowered deeper into the tube. OR simply open the jet a little with a torch tip cleaning file. any of these will work, some are better choices depending on circumstances. I believe Dick's forge was running properly a while ago so it's probably just a little altitude tweaking needed. The main thing to remember at this time Harris is this is FUN. don't sweat problems, every single one is teaching you something but not one is worth getting worried over. I don't think there's a blacksmithing problem been invented that can't be overcome by the knowledge base on IFI. How about a little one aspect experimenting? When you're trouble shooting you can't be changing more than one thing at a time and expect to find a solution by anything but luck. Here it is, build a little charcoal fire and just play with it using a small diameter piece of steel, 1/8"-1/4" should be plenty. All you're doing is observing how the steel behaves in what region of the fire. You'll be able to see exactly what the fire looks like in each zone and what it does to the steel. Best of all, you don't really give a hoot about what happens to the steel as you're not doing any forging at all. NONE. Just playing with the fire. A bed of blown coals has a distinctive look to it, zone by zone and with a little practice you'll be able to see raw air moving through the coals and that's exactly what you want to eliminate. You can decide what size charcoal works best for the size fire you need per job. How deep to mound it, the shape of the mound, etc. etc. It won't be long and you won't be able to sit next to a camp fire without critiquing it's burn zones and deciding which is good for what. The fire speaks to you, you just need to know the lingo. <wink> Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Harris Snyder Posted July 23, 2013 Author Share Posted July 23, 2013 Can't speak for coal, but charcoal will smoulder to ash even if it isn't directly above the tuyere. If you have a one inch thick layer of charcoal in a 6 inch radius around a 1 inch tuyere, the whole lot will burn away, not just the bit near and above the tuyere. Obviously that example is a bit extreme, but you get the picture. I suppose it's debatable whether that is a forge geometry or fire management problem, but having just built a little masonry charcoal forge with a tapered fire pot and using it for a few days I can say that it's definitely easier to control, and so I'd generally encourage others to think at least a bit about the design of a charcoal forge. In all honesty, one really would do well to have different shaped forges for different kinds of work in order to maximize fuel efficiency and ease of fire control. True, scale is the product of oxygen and hot steel. However, having a forge that supports a deep narrow fire makes it easier to forge with charcoal and avoid excessive scaling. Thanks for the advice on playing around with the fire. I did that a lot with my new charcoal forge, and it really is a good idea. I'll post some pictures of the new forge soon! It's basically just a tapered cast refractory fire pot (4 inches deep, sides built up with bricks). Overall I'm happy with it. I'm glad I have both solid fuel and gas forges. I like using charcoal when I want to feel traditional and rustic, but of course a gas forge is invaluable for batches of stuff, or when time matters... Quote Link to comment Share on other sites More sharing options...
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