westernironworks Posted June 22, 2012 Share Posted June 22, 2012 I am building my forge and i plan on making burning that have forced air from my air compressor. i was planning on running the air line piping through the inside of the forge but since it would melt i need to shield it some. i was planning on pouring refractory cement in the bottom and when i do i would run the piping through it so it would get shielded from the full heat of the forge. I will use 316 stainless steel pipe and how deep in the cement should i put it. i was thinking of having at least 1/8th inch of cement over the pipe or should it be more. i want it to get super hot but not to hot to soften the pipe so much it would burst from the low air pressure i would be running through it. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 22, 2012 Share Posted June 22, 2012 So you want to put hours on an expensive piece of equipment that requires regular maintenance and repair to do what can be done by a simple cheap blower? I don't understand the reasoning behind this. Compressors produce relatively small amounts of high pressure air where a forge uses rather large amounts of low pressure air---sort of the wrong tool for the job. I have seen some setups that use the high pressure air as an inducer to drag in more low pressure air; but they seemed to be designed for use before the omnipresent small electric motor was available. (It's absolutely *amazing* what was done with steam, hydraulics and pneumatics *before* the electric motor was easily available!) As for making it a recuperative forge google the sandia forge designed by Rob Gunter as an example of a simpler way to do so. Running them that close to the working surface will sap heat out of the forge. The Sandia design runs them through the exhaust stream after it has left the working area---a better and more efficient way in my opinion (found a reply I made on this subject on a different forum in 2004 when I googled...) Quote Link to comment Share on other sites More sharing options...
Dave Hammer Posted June 22, 2012 Share Posted June 22, 2012 What is your goal for the air you intend to put into the forge from a compressor? Quote Link to comment Share on other sites More sharing options...
gearhartironwerks Posted June 23, 2012 Share Posted June 23, 2012 Maybe you should consider building/using a ribbon burner with forced air from a blower. No wear and tear on a compressor that will run continually. That being said, you can, however, jazz up a venturi burner by using small amounts of compressed air to the inlet controlled by a small valve at the inlet. I'm not a fan of having an expensive compressor run continually when forging when there are simplier solutions at less cost. John Quote Link to comment Share on other sites More sharing options...
westernironworks Posted June 23, 2012 Author Share Posted June 23, 2012 well for the compressor i figured it wouldnt use alot of the air so the compressor would be turning on an off periodically but i suppose i could just get an electric fan for the forced air. I didnt think that the air line running through the forge would sap a ton of heat from it and keep it from reaching a very hot temp. i guess i will be running it around the exhaust then which is gonna be out the top of the forge. this is the exact reason why i posted here before i have gotten too far in the construction to change anything. Quote Link to comment Share on other sites More sharing options...
Dave Hammer Posted June 23, 2012 Share Posted June 23, 2012 I would recommend you study gas forges that are available for purchase (to see how others have solved the "air source" issues (and uses). Quote Link to comment Share on other sites More sharing options...
westernironworks Posted June 23, 2012 Author Share Posted June 23, 2012 i have seen lots of forges and was trying to do burners like the ones i liked especially for fuel effiency. at the start i will be running the air from my air compressor until i get a fan i wanna use thats cheap enough. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 25, 2012 Share Posted June 25, 2012 I don't see where heat removed from the firebox and fed back in would make things hotter? If it's not sapping a lot of heat from it then it's not heating up the input air much either; but every BTU used to preheat the input *is* coming out of the firebox's heat balance. Stealing it from the exhaust making the exhaust cooler and the input hotter looks like a heat balance on the positive side for the firebox. It's a good thing to think about; as reducing energy usage goes directly to the bottom line for us. Also factor in buildability and maintainability on your system as there are things it's possible to do that may not be practicable to do. (Doing all your forging in a hard vacuum would certainly deal with those scaling and decarburization problems! but the PPE tends to be expensive...) Quote Link to comment Share on other sites More sharing options...
westernironworks Posted June 25, 2012 Author Share Posted June 25, 2012 yeah i totally wasnt thinking that it would steel heat from the forge by putting it inside,i was just thinking it would heat up really good hehe. i bet as i was building it i would have realized but putting the line around the exhaust will do the job. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted June 25, 2012 Share Posted June 25, 2012 You can tell when I'm teaching a lot of classes as I burn the hair off my forearms to demonstrate the dragon's breath to new students---really opens their eyes to how much heat is coming out of the forge and not to forget about it if they drop something right in front of the forge. I've thought of making a burner shroud that suspends the burners in a larger pipe to allow exhaust preheating. However I'd have to use a blown burner so I can make SURE that no exhaust gets re-run and no fussy little parts would get heat damaged in the burner itself. Quote Link to comment Share on other sites More sharing options...
westernironworks Posted June 26, 2012 Author Share Posted June 26, 2012 To get it working fast i am not gonna run the air pipe around the exhaust at first but i am gonna make my exhaust hole round so it will be easy to match the pipe up to it later. I am hopin to have some pics up of this monster by the end of the week. i can never just go with something simple and small to start with hehe. Quote Link to comment Share on other sites More sharing options...
Dodge Posted July 1, 2012 Share Posted July 1, 2012 Just a thought here. The "exhaust hole" is generally where the steel/iron/metal is inserted to heat it... "i can never just go with something simple and small to start with hehe." I truly understand that feeling, but with gas forges, its really best to not try to re-invent the wheel so to speak. There are too many good designs out there that folks have already worked the bugs out of :) Quote Link to comment Share on other sites More sharing options...
westernironworks Posted July 3, 2012 Author Share Posted July 3, 2012 yeah i am not doin anything new(now) just gonna go with a basic set of 3 burners with forced air thats gonna eventually have a heated pipe for more effiency. right now the forced air is gonna be run by my massive industrial air compressor but gonna get an electric blower when i can find one cheap enough. Quote Link to comment Share on other sites More sharing options...
Rich Hale Posted July 5, 2012 Share Posted July 5, 2012 It seems you are commited to this design and are gonna build it....however there are a LOT of gassers that do not use forced air at all..I hav ethree and can weld in all of them,,, cannot get any simpler than that. Quote Link to comment Share on other sites More sharing options...
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