My new, almost done, bigger blast furnace. It was a 5 ft. tall pressure tank for a water system. I cut it down and refit the bottom to it, marked where I intend to cut the lid, fabricated a hinge and did a mockup for fit and alignment.
Been work'n on completing welds for the hinge and fabricating some additional supports for the lid/hinge attachment. Will shoot some pics of it all assembled tomorrow.
FC's New Furnace Build
FC's New Furnace Build
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FC's New Furnace Build
how tall is that going to be?, looks pretty long laying down
David and Charlie aka the shop monster
If life seems normal your not going fast enough" Mario Andrette
If life seems normal your not going fast enough" Mario Andrette
FC's New Furnace Build
That looks great Frank 
When life gets tough, remember: You were the strongest sperm
FC's New Furnace Build
26 inches, not counting the lid. It'll have 2" clearance between the crucible and the interior refractory (all sides and top).dallen wrote:how tall is that going to be?, looks pretty long laying down
FC's New Furnace Build
what you going to use in the lid, hope it some light weight stuff, I would use 3000 degree insulating refractory for the whole furnace but that's just me, although the exhaust port it what takes the beating from the heat in a furnace. Anyway that's been my experience with my two large furnaces.
David and Charlie aka the shop monster
If life seems normal your not going fast enough" Mario Andrette
If life seems normal your not going fast enough" Mario Andrette
FC's New Furnace Build
My mistake... it's a smidge over 24 inches (without the lid) from the floor to the top where the lid pivots off. Yes, 3000 degree refractory will be the lining. I don't know why your's takes such a beating at the exhaust port. I've had a thousand or more burns in my last one and it never eroded the interior wall nor at the exhaust port at all. I run mine where the flame actually forms a nice rosebud an inch or so above the port. I watch for the flame to turn a tint of green and lock in the regulator and air setting and keep that flame visible (and at the same size) the entire burn. Even the paint on the metal at that exhaust port doesn't burn. But it'll melt a #20 crucible volume of bronze up to pouring temp within 40 minutes with less than 5 gallons of propane.
The hinge body I build has a half turn thread-like ridge. The lid shaft has a hardened steel tab that rides atop that hinge's thread-like curved ridge. I don't have to actually "lift" the lid's weight, rather, apply a bit of upward lift assistance while pivoting the top while the lid, itself, rides that hinge ridge and smoothly lifts about 3/8" up and pivots to the side with little effort.
The interior wall will have its own thread-like interior finish. I'll make the form to create the interior wall then coil a narrow garden hose around that form which will make pronounced screw-like ridges on the cast furnace wall face up to about 6 inches from the top. To keep the threads rounded (instead of having thin tips) I'll use wax and melt a bead between each coil and smooth them uniformly rounded by hand. The idea is to create a threaded faced wall 6" above the furnace base and up to within 4 inches of the top. This will surround the bulk of the crucible with those raised ridges. Once the form is completed I'll insert that (centered) into the furnace and have cut in the intake port to align with the intake port of the furnace outer shell. I'll use thin wall PVC to create the intake hole through the furnace cast wall. Once it all sets up, I'll dismantle the interior form, remove the coiled hose & wax, then after 24 hrs of drying, I'll fire up the furnace at idle and burn out the PVC and cure the furnace lining.
When the furnace is fired with intent to melt metal, those coiled ridges will begin to glow before the crucible does and act like a toaster or electric kiln's elements. This gives radiant heat to the crucible long before the interior wall begins to glow which speeds up the melt coming to temp. It also forces the interior flame to coil around the interior & crucible (more than otherwise) and actually reduces the air and fuel mix proportionately so you get more heat more efficiently with less time. I built one like this years ago and actually melted stainless steel in the same time it normally takes to melt bronze (approx. 30 minutes, 2-/12 gallons of propane). The interior of that furnace was white hot in no time with more throttle and air added. Although, I never had to inject more air beyond my blower's capacity.
The trick to keeping the threaded refractory face from eroding is to add about 30% of metal filings in with the refractory used to cast that section of wall. The filings melt (when the furnace is lit and brought up to 2000 degrees and chemically combine with the refractory cement and creates a slag substance that's tough as the hubs of hell. Even metal grinding disks can't grind the stuff. You'll wear down a couple disks before you'll even begin to notice any actual abrasion done to the refractory finish.
The hinge body I build has a half turn thread-like ridge. The lid shaft has a hardened steel tab that rides atop that hinge's thread-like curved ridge. I don't have to actually "lift" the lid's weight, rather, apply a bit of upward lift assistance while pivoting the top while the lid, itself, rides that hinge ridge and smoothly lifts about 3/8" up and pivots to the side with little effort.
The interior wall will have its own thread-like interior finish. I'll make the form to create the interior wall then coil a narrow garden hose around that form which will make pronounced screw-like ridges on the cast furnace wall face up to about 6 inches from the top. To keep the threads rounded (instead of having thin tips) I'll use wax and melt a bead between each coil and smooth them uniformly rounded by hand. The idea is to create a threaded faced wall 6" above the furnace base and up to within 4 inches of the top. This will surround the bulk of the crucible with those raised ridges. Once the form is completed I'll insert that (centered) into the furnace and have cut in the intake port to align with the intake port of the furnace outer shell. I'll use thin wall PVC to create the intake hole through the furnace cast wall. Once it all sets up, I'll dismantle the interior form, remove the coiled hose & wax, then after 24 hrs of drying, I'll fire up the furnace at idle and burn out the PVC and cure the furnace lining.
When the furnace is fired with intent to melt metal, those coiled ridges will begin to glow before the crucible does and act like a toaster or electric kiln's elements. This gives radiant heat to the crucible long before the interior wall begins to glow which speeds up the melt coming to temp. It also forces the interior flame to coil around the interior & crucible (more than otherwise) and actually reduces the air and fuel mix proportionately so you get more heat more efficiently with less time. I built one like this years ago and actually melted stainless steel in the same time it normally takes to melt bronze (approx. 30 minutes, 2-/12 gallons of propane). The interior of that furnace was white hot in no time with more throttle and air added. Although, I never had to inject more air beyond my blower's capacity.
The trick to keeping the threaded refractory face from eroding is to add about 30% of metal filings in with the refractory used to cast that section of wall. The filings melt (when the furnace is lit and brought up to 2000 degrees and chemically combine with the refractory cement and creates a slag substance that's tough as the hubs of hell. Even metal grinding disks can't grind the stuff. You'll wear down a couple disks before you'll even begin to notice any actual abrasion done to the refractory finish.
FC's New Furnace Build
I've heard of the metal filings addition before somewhere... Probably from you 
I might try it if I build another furnace. I wonder how it would work in a cupola fired with coke? They eat up the lining where the Iron pools.
I might try it if I build another furnace. I wonder how it would work in a cupola fired with coke? They eat up the lining where the Iron pools.
quando omni flunkus moritati 
FC's New Furnace Build
The man who began this thread, Gypsy Tinker, has just resurfaced on the other forum following a multi year hiatus.
Richard
Richard
FC's New Furnace Build
Well, here she is fully assembled. One of the pics shows how that hinge is set up. All that's lack'n now at this stage is cut'n the blower port hole at the bottom and incorporating a pipe sleeve around it for the blower pipe to insert into; finish cut'n out the top lid hole; finish cut'n the lid off the main body now that everything's assembled and aligned; add'n a length of round bar stock steel as a lid handle; then lining the entire furnace with refractory.
Been eyeball'n the overall set up some today and just might cut about 2 or 3 inches off that bottom skirt. The bottom of the furnace tank, itself, is about half the depth of that bottom section. That skirt serves only to give a solid, level foundation for the furnace to sit upright upon. A couple less inches to have to lift out a #20 crucible full of melt is a good thing. I gotta keep it in mind to work smarter than harder, so I guess that answers that notion. Best that gets done while the unit is reasonably light weight.
Been eyeball'n the overall set up some today and just might cut about 2 or 3 inches off that bottom skirt. The bottom of the furnace tank, itself, is about half the depth of that bottom section. That skirt serves only to give a solid, level foundation for the furnace to sit upright upon. A couple less inches to have to lift out a #20 crucible full of melt is a good thing. I gotta keep it in mind to work smarter than harder, so I guess that answers that notion. Best that gets done while the unit is reasonably light weight.
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FC's New Furnace Build
Oh, and of course incorporating my trademark "sculpted steel flame" into the top of the lid hinge attachment I do for all the furnaces I've built. Can't forget that on the list of "to-do's to finish.