marcusb Posted November 30, 2016 Share Posted November 30, 2016 Anyone know of any plans out there for burner design for one of these forges? I have searched here and online and found some discussion and top pics but no drawings etc? Also does anyone know of a USA supplier of chips or suitable substitutes? I have a crap ton of crucible block that' s heavy and tough but I could chip it is needed. Fuel source will be natural gas and I can supply it at any reasonable pressure. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted November 30, 2016 Share Posted November 30, 2016 The little bit of dependable information on gas based ceramic chip forges can only be gained from brochures of English ceramic chip forges. I can tell you that one or more burners must blow flame into something like a plenum chamber below an upper chamber that holds the chips; this creates severe problems and limits. Because the lower chamber (plenum) must hold up the upper chamber, with its lode of chips, plus water part is being heated, at elevated temperatures. Very hot standard burners cannot be used, since this ended up with partially melted ceramic structures last time some one tried this (back in 2006). After helping encourage a willing victim into into this mess, a decided that only a larger, and lower temperature flame, from a fan-blown burner could avoid a repeat of it. That was then and this is now. If I tried to build such a forge today, I would attempt to cast ribbon burners into a support structure below and beside the chips instead of building a plenum chamber, as the best possible solution. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 9, 2016 Share Posted December 9, 2016 The company is Flamefast in the UK: http://www.flamefast.co.uk/ Quote Link to comment Share on other sites More sharing options...
Frosty Posted December 9, 2016 Share Posted December 9, 2016 I used to do SCA events and the Harolds were usually sputtering annoyingly about a propane forge not being period, the real chief of period police complained about safety glasses. About that time the chip bed forge came to my attention along with the Internet and I spent some time working out how to build one. It's been a long time but IIRC one anyway claimed the plenum below the chips supplied air gas to be burned in the chip bed. Flamefast were IIRC "burning" fuel air below and in the chip bed. I gave up on the project for two main reasons. First I told the harolds to pound sand and leave me alone, when they puffed up I asked for a show of hands from the SCA members within shouting distance. The Harolds were voted NO almost unanimously. The other main reasons were I couldn't winkle out a good plenum within my hassle limits and worse were the chip's shape. The chips need to be the correct shape, just as in a furnace type forge a chip bed is a reverberatory device, the fire heats the chip bed and the chip bed heats the work via radiation and direct conduction. Getting the chips to work properly means getting the shape right. You MUST be able to slip the work into and out of the bed without damaging it AND the fire has to circulate through it evenly. Spheres were my first thought, they're slippery, they don't key into each other so work should slip in and out okay, there's a consistent gap where they contact each other so flame can circulate. Sounds good unfortunately a sphere has the absolutely WORST surface to volume ratio of any solid form. This means it takes more fuel to bring it to temp and radiates heat the slowest of any solid polygon. Well, my next thought was roll a thin sheet and break it up but the jagged faces "key" meaning they fit together like a jigsaw puzzle and pack hard. Work wouldn't slip in and out without considerable force or physically lifting and covering the work with chips using a scoop. Not good. The shape needs to maximize the surface area to volume ratio and that takes molds. I finally settled on a 3D triangular pyramid sort of shape with concave faces and rounded edges and points. The shape can't key, in fact there's no way they can contact each other and block the flame flow. I hand modeled a couple dozen from Pyramid Super a superior phosphate 4,500f refractory that's no longer manufactured and is a LONG way from insulating. Anyway even a couple dozen was a major PITA to make and they weren't very consistently sized but close enough to test. The shape worked fine, even a very soft flame flowed right through the bed and I went so far as to put the chips in a can and blow the flame through the stack. Unfortunately you need a couple few hundred chips and you don't want a dense refractory, even KastO-L-ite bubble refractory is kind of dense. I think mixed with zirconia it'd be near ideal. That still leaves a person making the things. Unless a person wanted to make commercial runs I don't see a practical method and believe me hand forming the things is a PITA. I'm with Mike I'd ditch the plenum and make a multi port Ring burner and lay the chips directly on it. You bet the ring burner would have to be made of high temp refractory and would have to have a high fuel air velocity to keep the burner plenum cool enough it didn't pre-ignite the fuel/air. This is a problem my current ribbon burners are experiencing, I was running the forge around 2-3psi at the last meeting and after a couple hours the burner blocks got hot enough both burners started back firing. I need to either run them at higher pressure so the fuel air velocity is higher than the rate of propagation (flame front) which gets faster as the fuel air gets hotter. The higher flow rate would also help keep the burner blocks cooler. Another remedy I hope to avoid would be to add an insulated layer to isolate the block from the forge interior. What a PITA that'd be. All that long winded description of my current multi port burners is to illustrate why a Ring burner under a chip bed would be problematical. A person would need to isolate the ring or feed fuel air through it fast enough to keep it cool. Maybe wrap the propane tank in a heat exchanger to chill the intake air? Run the air and propane through a pre-chiller? Making a chip bed forge hot enough to do out style forging say weld with would be big gooey gobs of FUN boys and girls, please keep us posted. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted December 9, 2016 Share Posted December 9, 2016 I think I'd go induction before chip-forge. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 10, 2016 Share Posted December 10, 2016 I did notice yellow hot chips in the Flamefast chip forge photo, above text claiming a 2729 F CLAIMED temperature rating, which we all know is going to be 400 degrees hotter than pure white incandescence: so I'm calling B.S. on their so called 'facts.' Also, I think ceramic ships are best used as a secondary heat source for hard brazing without oxygen, while surface radiation from the surrounding walls of a straightforward gas forge is better for forging and welding; that's my take on the deal, but I'm willing to be educated on the matter. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted December 10, 2016 Share Posted December 10, 2016 Well we all know the difficulty of getting accurate colour when photographing hot stuff. Could be they didn't make the correct colour adjustments. (Which does not give me a warm and fuzzy about folks selling stuff as I would hope they would go the extra mile to be accurate.) Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 10, 2016 Share Posted December 10, 2016 We inhabit one universe, with its own set of values, and they inhabit another...shall we collect the money-verse? In their universe the only values have to do with stock prices. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted December 10, 2016 Share Posted December 10, 2016 Yes I know that I have a "Non-Standard World View" to expect people to know anything about their own products---I've met folks selling anvils, new in a store , that didn't know the difference between cast iron and cast steel. Quote Link to comment Share on other sites More sharing options...
Frosty Posted December 11, 2016 Share Posted December 11, 2016 Ceramic chip forges never look as hot on the surface as they are in the heart. If anything photos look hotter than they are. I also admit what I know about a ceramic chip bed forge is hearsay mostly from years ago. I agree with how useful a chip bed forge is for general smithing and would go with induction long before a chip forge. That would be the kind of blacksmithing I do and I have to admit I've never used a chip bed forge and could be way off base. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 11, 2016 Share Posted December 11, 2016 I think we are agreed that chip based blacksmith forges aren't a slick use of technology, but for those who have a bad case of "I just gotta": There are rubber based molds that can be made to cast the chips in, and I think the standard formula for graphite crucibles would make better use of the fuel, having much better rates of heat transfer than high alumina based refractory. Quote Link to comment Share on other sites More sharing options...
Ian Wille Posted December 12, 2016 Share Posted December 12, 2016 Funny that you mention graphite crucible formula for the chips, Mike. I rigged up a chip (more like chunk, about like nut size coal) forge using broken up graphite based crucibles from a local foundry several years ago. ( Link to my previous post on this )The burner was a 5" square ribbon burner with about 25 ports, mounted in a firepot about 2" deep. The blower I was using was the 112cfm blower from Kayne and Son. The crucible pieces worked alright, but tended to stick to each other, which made it fun to get work into and out of the chip bed . They also tended to "absorb" scale. Not bad, and has potential, but I ran out of spare time to do more R&D. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 13, 2016 Share Posted December 13, 2016 Well dang; this thread has taken off, and seems more important than I'd have figured! If there is one thing I like to read, its peoples personally takes on equipment; more, more Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted December 13, 2016 Share Posted December 13, 2016 Well it is nice that ribbon burners can turn the biggest problem with ceramic chip forges into an asset, but being the stinker I am...what could be even better? Why introducing the heated air in the drilled openings and the gas in the bottom of the chip bowl in separate openings, to keep most of the heat inside the chips, where it belongs Quote Link to comment Share on other sites More sharing options...
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