FlyingXS Posted December 25, 2015 Share Posted December 25, 2015 Got my Isowool, 1" Thick and ended up with the top heat rating and density as the one I paid for was out of stock so they gave me the better one at no extra charge. I plan to use the kiln tiles as the forge base. They are the white ones and look a bit like marble tiles. If they fail I can substitute the orange fire brick in. Making two forges one from a 9kg lpg gas bottle and the mini forge. The large RHS tube will become the front mouth, the smaller RHS is the rear mouth to allow for long items to poke out the rear. Hinges are done hinges just need to notch out the front to follow the curve. Hinge is made to match the width of the forge mouth. Next I need to make the feet and fit them so I can set the baseline foe horizontal to which the mouth can be cut parallel and the hinge pin at 90deg. Only problem is I have to wait for a non fireban day (Summer here and bush fire risk area) to light the coke forge to bend the feet. Quote Link to comment Share on other sites More sharing options...
ForgeMan32 Posted December 25, 2015 Share Posted December 25, 2015 That's a great looking set up. Especially the mini forge that's an awesome little stainless contraption. BUT,one thing I do see from the pics is that the propane tank forge looks to have a GALVANIZED burner tube and assembly . please correct me if I am wrong . I've made a few gas forges and I always shoot for black iron for those parts. Just looking out for a fellow smith and those parts don't get terribly hot but the burner tube itself may get hot enough to put off zinc fumes Quote Link to comment Share on other sites More sharing options...
FlyingXS Posted December 25, 2015 Author Share Posted December 25, 2015 Cheers mate I appreciate the concern. Only the pipes and the gas valve are plated, the others parts are all plain cast steel. The entire burner assembly comes from a gas fitting company that has a specific section for knife makers, blacksmithing etc. SO WHILST NOT 100% I'm reasonably confident it will be ok. Quote Link to comment Share on other sites More sharing options...
Everything Mac Posted December 25, 2015 Share Posted December 25, 2015 I'm no expert but I'd have thought the tube itself would not get "that" hot? Enjoying the build so far. It's nice to see threads like this from time to time. Be sure to keep us updated. All the best Andy Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted January 3, 2016 Share Posted January 3, 2016 Loved the photos of the hinge; they really were worth a thousand words. Quote Link to comment Share on other sites More sharing options...
FlyingXS Posted January 3, 2016 Author Share Posted January 3, 2016 Fired up the coke forge and bent the feet up. Made a rebar filleting knife while I was at it. Welded the feet on to set the base horizontal. Plan was to fit the hinges before cutting the last few tabs that held the door on but that left me with a guess as to the location of the mouth. So I cut the door off today. New plan is to line it and fit the floor measure the height. Tack the door back in place cut the mouth and fit the hinges. Not 100% sure where the burner is supposed to point. So I'm thinking of pointing it at the centre of the floor. Quote Link to comment Share on other sites More sharing options...
Kozzy Posted January 3, 2016 Share Posted January 3, 2016 1 hour ago, FlyingXS said: Not 100% sure where the burner is supposed to point. So I'm thinking of pointing it at the centre of the floor. I too would like to hear some discussion on where to point burners. A lot of the commercial forges seem to point dead center--straight at the likely location of stock placement--but there have been some hints in the forums that offset is better (iirc, it was said to help reduce scaling and part-surface over-heating). If I had to guess (since I don't have a working gas forge yet)...I'd guess that pointing at one side of the shelf would allow you the most flexibility in placement of stock for heating. However, that also means your stock is heated less evenly. So what's the right balance and is it even a big enough issue to worry about? Quote Link to comment Share on other sites More sharing options...
Frosty Posted January 3, 2016 Share Posted January 3, 2016 How you orient your burners depends on a couple things: What you want the forge environment to be is probably the most important. A gas forge tends to heat everything that's even close to the door trying to get an isolated or spot heat is a problem. This makes orienting the burner perpendicular to a specific spot desirable. At least to a degree and presents problems. Orienting the burner on a tangent with one face of the liner to invoke a vortex distributes the flame and heat more evenly in the chamber. I prefer a tangential alignment but that's me. When a propane flame impinges a surface high energy chemistry takes place and most refractories degrade more rapidly than just temperature dictates. This is also true for fuel oil burners so I assume any hydrocarbon fuel air flame is pretty chemically reactive. This means how the flame impinges on the liner makes a difference. The closer to the center of the flame the more unburned fuel and air there is to react with other things it meets. Aiming the flame directly at a surface exposes the surface to the center of the flame where max heat is generated as is the most unburned chemistry. Impinging at a shallow angle means contact with the outside of the flame column where most of the fuel air has been burned and it's cooler. It's not that the flame is necessarily cooler but the impact zone is now stretched across most of the forge liner so it physically can't have the same effect chemically. Most tangential alignments are across the top one side to the other. This puts the work under an arch of HOT liner and maximizes exposure to hotness. Tristan has up draft burners ported through the floor aimed up one wall then across the roof. I've used his forges and they work very well. I was really surprised that nothing seems to fall into the burner. A burner flame aimed straight down onto the floor distributes heat in a circle from the center of impact. however, when you lay a piece of work in the flame the floor is now in a heat shadow so the forge floor loses heat without being replenished by the flame. The work doesn't absorb heat so well from the flame as it does from IR from the liner. Mike, other folk and I have talked about kiln washes and why before so I'll let that lay now. Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted January 4, 2016 Share Posted January 4, 2016 Probably the best all round position is from the bottom facing up, so far as overall efficiency is concerned. But, the most popular position is about twenty degrees off top dead center. As with so many things, it's not just about efficiency, but more about personal preference. I would recommend that newbies use a loose kiln shelf or firebrick and play with burner positioning by trapping tunnel forges between angle irons before deciding how to aim their burners. A little extra effort to make the right-for-you decision is always a good investment. Quote Link to comment Share on other sites More sharing options...
Frosty Posted January 4, 2016 Share Posted January 4, 2016 Mike: thinking about experiments and minimizing flame impingement your talk about IR baffles got me to wondering about hanging a sacrificial flame baffle in the forge. Something to take the brunt of the flame contact but not disrupt circulation. It was just a flash idea a little while ago and I've been kicking around ways to hang pieces of kiln shelf. Thoughts? Frosty The Lucky. Quote Link to comment Share on other sites More sharing options...
FlyingXS Posted January 5, 2016 Author Share Posted January 5, 2016 Thanks for the replies guys. I think I'll have to come back and reread them after breakfast and see if I can absorb it all a bit better. Quote Link to comment Share on other sites More sharing options...
Mikey98118 Posted January 6, 2016 Share Posted January 6, 2016 Frosty, I think that's a good idea; a curved one could be shaped from Kast-O-lite 3000; I don't think it would need to be all that large. Or high alumina kiln shelf could be cut and mortared together as a flame impingement shield; either would allow the burner flame to be pointed upward for greater swirl and greatly reduced scaling. kiln shelving could be cut into any convenient shape, with narrowed arms penetrating the steel end pieces, to hold the wider impingement shields centered on the flame or flames like targets, positioned say 1/2" between them and the finish coated ceramic fiber. Quote Link to comment Share on other sites More sharing options...
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