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Mikey98118

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Making do

We Americans tend to be "spoiled for choice," and forget that this isn't so in other places. The latest refractory bricks, or the latest insulating hard refractory may be hard to find in countries just as modern as ours, but not given to excess. What to do when you can't find the refractory needed? Make your own.

Hard refractories are available most places. Perlite is a gardener's soil additive available most places; mixed them together for a workable alternative to insulating hard refractories like Kast-O-lite 30. Can't find the bricks you want? Turn your homemade refractory into bricks. This worked for home casting hobbyist for years before Kast-O-lite 30 was available. My first casting furnace had a two inch tunnel wall made of it, and it got yellow-white hot inside. The main difference between a tunnel forge and a casting furnace is that one stands vertical and the other rests horizontal.

One third Perlite to two thirds refractory by volume. 

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Deimos,

A way around import tariffs may be to have someone in the US (perhaps a volunteer from IFI) order whatever you need then re-ship it to you as a personal gift (after you have gifted him or her the appropriate amount of currency).  Usually, personal gifts under X amount of value do not have the same import duties as something ordered commercially. I can't say for sure this would work but if it does the only extra cost over the cost of the item is the postage/shipping from the US.

Also, once travel is happening again you might get someone to hand carry an item over for you.  I know that I'd be a mule for something in exchange for some good Dutch beer and converstion if I were planning to visit that part of the world. 

"By hammer and hand all arts do stand."

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4 hours ago, ThomasPowers said:

OK as I remember things like Kaowool are also used as insulation for Boilers for large buildings.

The kaowool is not the problem, i found stuff like that. 7 meter long rolls. Its the refractory that is the problem.

 

4 hours ago, George N. M. said:

A way around import tariffs may be to have someone in the US (perhaps a volunteer from IFI) order whatever you need then re-ship it to you as a personal gift (after you have gifted him or her the appropriate amount of currency).

 The import tax over here is ridiculous, since they cant open all packages, they just guess what i would be worth and give you the bill. My wife ordered a book from Vincent Price his daughter, payed about 35 euro for it and had to pay almost 50 euro on tax. Sending it as a could work, unless they have enough reason to open it anyway (since we are talking about powder here) 

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  • 2 weeks later...

A a gas forge is simply a way to preserve heat, and put it to work. Most of a flame's heat goes right out the exhaust port, so you are trying to preserve what you can in the forge linings. fuel gas and air used to be relatively cheap, compared to construction materials. So, forge linings only needed to soak up as much heat as they could, while not crumbling to dust. Hard clay bricks did that trick well enough. Fuel gas was cheap and air was free.

Fuel gas got hotter, and costlier, but air was still free. During these years, lining materials were steadily improving, and so were forge designs.

So, here we are today with lots of materials; some expensive and hard to find; others still pretty cheap. Air is still free-so far--and forge designs cost nothing but a little investment in the learning curve. Forges still exhaust most of their heat out the exhaust  port. "This ain't rocket science." Do the math. What math? Simple addition and subtraction. You are trying to accumulate (add) heat in a small place. How? by subtracting as much heat as you can from the flame and exhaust gases, before they can escape out of the exhaust. There are even SIMPLE ways to rob heat from those gases as they exit.

We like to discuss the latest and best of this and that here on IFI, because we are tinkerers at heart. Using the latest and greatest, we can get a forge up to 2750 F. Using yesterday's materials--with the latest designs-- you can get your forge up to 2300 F. Are you trying to melt steel or just hammer and weld it? Don't allow "the best" to be the enemy of "good enough."

A bad forge is a crude gas oven. A good forge uses gas flames to create a radiant oven. Once your forge passes 2000 F, most of its heat transference into the steel is radiant. This goal is achieved one small step at a time, like building a brick wall; not buy finding "the very best" materials.

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Air openings and other changes in small repurposed torch-head burners

It is fairly easy to add a thicker stainless steel tube snugly over the very thin (0.035" typically) stainless steel flame tube of an air/propane torch mount burner; this will protect the flame tube's thin wall from vanishing from high heat oxidation for a considerable time, if no performance improvements are sought.

Eventually the end of the flame tube will oxidize away. At this point the flame will become destabilized, and the torch-head must be replaced, or upgraded. "In for a penny in for a pound" time start then. You can either spend your money buying a new torch head, or spend no more, and perhaps a less, upgrading your torch-head into a proper equipment burner.

The first step: is to add a spacer ring around the doubling tube's forward end, and then add a third tube. around the spacer ring; this is your new flame retention nozzle. What sizes? Try for something approaching 1/16" to 1/8" thick wall on both new tubes; these become your minimums and maximums. But what about length? The amount of overhang needed for a flame retention nozzle to work properly is equal the the diameter of the flame tube, plus 1/8" extra to allow you to adjust the flame's hardness by pushing the nozzle back and forth on the flame tube. To this measurement add whatever length you found convenient in the spacer ring's length.

Second step: A flame retention nozzle is going to try to induce more air into the burner, and so you will probably need to improve the old torch-head's air openings; if they are just holes in the flame tube,  a drill little larger bit inserted into each hole, and then turned at an angle leaning toward the flame tubes rear, should do the trick. If the air openings are in a thicker walled brass fitting, do use the same method. If the air openings air oval shaped, use a small drill bit to to create the desired bevels in it rear and forward edges, without creating any appreciable changes in their sides.

Step three: If your torch-head is left on full cylinder pressure, chances are that its gas jet will need little or no modification; in that case, use nothing more than torch tip cleaners to enlarge it. If you enlarge the gas orifice too much, than you will have to add an adapter hose, regulator, and POL refillable fuel cylinder to the burner, to get it back under control.

 

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Many perfectly adequate burners need a secondary air source for complete combustion. It is also a preferred method of reducing scale, to "de tune" a burner, to provide some secondary flame, even though the burner is capable of total primary flame combustion. In either case some secondary air is needed to keep carbon monoxide from accumulating in exhaust gases, and of course, to conserve forge heat.

Recoupingheat lost through exhaust gases is also an attractive goal, however it can be managed. But trying to heat incoming air in the burner has thus far worked out poorly, because of safety and maintenance issues.

But, if small air passages were left in refractory walls, pehaps by the inclusion of straws, etc., to create them, and then burn away one or two such passages to heat incoming secondary air near the burner opening...

 

Close enough for the flame to induce air flow, without overheating the burner's mixing tube.

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Flame king Dual 1-pound Propane Cartridge Carrier with female P.O.L. outlet ($36.12); this device securely holds two one- pound propane canisters, screwed into two male QCC inlets (for throwaway canisters), which are part of a gas manifold that ends with an external POL inlet; this works exactly the same way as the main valve on a refillable propane cylinder. The whole unit is contained in a hard-plastic carrier; including handle. At last, a legal way to transport propane in your car; not to mention legally store and use it inside your garage.

    Flame King also has refillable (D.O.T. compliant) 1-pound propane canisters ($19), along with a D.O.T. compliant refill system; available on their website.

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  • 2 weeks later...

Okay, I need some wisdom here.  What is the halfway point between soft, insulating firebrick and dense, thermal battery-like firebrick?

NC forges don't even have insulation in the bottom, rather they have a firebrick.  It's still pretty tough, yet it insulates enough that the bottom of the forge does not get too much heat.  And it heats up quickly, despite having an inferior burner design.

High alumina kiln shelf works ok, but is expensive compared to firebrick, at least in my neck of the woods.  I could pour my own floors, but as I am hoping to turn this into a production item I would much to prefer to use what is available on market already.

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What are your priorities?   Do you want maximum resistance to flux?  Resistance to mechanical damage from stock?  Insulative properties?

For a replaceable floor, the split fire bricks are not a bad choice if you don't want to spend the money for the high alumina kiln shelves and you have insulation below them (fiber blanket, fiber board or insulating fire brick).  In my experience Kast -O- Lite 30, regular kiln shelf, and regular fire bricks are all susceptible to damage from flux. Coating the exposed surface with something like Plistex or Matrikote makes them more resistant. Ceramic fiber materials and insulating fire bricks are highly susceptible to damage from flux.   Any way you look at it a forge lining is a consumable item and the floors tend to sustain more damage and need to be replaced more frequently than the other interior surfaces.

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1 hour ago, Alphafarrier said:

but as I am hoping to turn this into a production item

Turn what into a production item.

build a forge designed for production work?

Or production line forge building? 

They are two different things.

Frosty The Lucky.

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costs to build a commercial item don't break down the same way as retails prices for small orders. Also, weight and breakage complicate those prices, because it's all the same problem to your costumers. Finally, ease of set up for the forge materials are going to matter to  the customer, since you aren't going to be able to set up the forge as a turn-key item, and have it survive shipment.

Take a second look at forges for sale, with these things in mind, and you're a lot more likely to find that the latest materials are less costly then you first supposed :)

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Buzzkill: My priorities are something that can withstand some mechanical abrasion and be somewhat resistant to flux, but not take forever to heat up.  I tried splits on the floor, it took forever to heat.  I need a forge that comes up to a reasonable temp in a few minutes without using a ton of fuel.  Kiln shelf works ok.  It's just costly.

Frosty: Production line forge building

Mikey: I get your point.  I'm just asking what this material might be, and where I might find it.  I am turning to you guys because I'm not a rank amateur on this point, I'm actually confused.  I have disassembled and inspected literally almost every mainstream propane forge in the market (and worked extensively out of many of them, especially NC, Forgemaster, Colleoni, Blacksmith, Swan, Hall, Cliff Carrol, etc).  I have talked all the major high temp insulation companies at length about their products (and dozens of smaller ones).  And yet I can't seem to find this brick that this little company from North Carolina is using.  It has to be cost effective (because they are the budget forges), yet it can withstand quite high temps, is somewhat insulative, is resistant to flux, is not as dense as the dense firebrick, nor as heavy.  It is more porous.  Any ideas?  

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Hard refractory fiber board is prettty standard for the reasons I've already listed. The two most successful OEMs use it wherever they can because of that. And, no, you you won't like their prices either.

BUT, if you don't start your figuring by budgeting shipping cost, and keep breakage minor, you had better figure on only selling your product locally:P

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I just ran across this on Larry Zoeller's web site.

 

Used Freon Tanks
Free used Freon Tanks all you have to do is either pick them up from my 47136 locations or pay the USPS shipping charge.   This are great for building a small single burner forge. Send me an email if interested.   I currently have 16 available.

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  • 4 weeks later...

Tony Hansen has produced a high emissive refractory formula for use as kiln shelving, ceramic flame retention nozzles, etc.; it can be made with a formula consisting of 80% Zircopax Plus, plus 16.5% 60-80 mesh molochite grog. 3.5% Veegum T, and 15.3% water. 4.2% drying shrinkage after firing. Fire to center, then fire as high as possible for maximum strength.

 

The 60-80 mesh molochite grog reduces drying shrinkage and provides mechanical stability in the refractory mixture.

 

Veegum T is a smectite (clay) blend, used as a suspension aid and plasticizer.

 

Zircopax Plus (Superpax, Opax, Ultrox) is a powder containing zirconium silicate (ZrO2:SiO2) particles With a melting temperature of 4000 F, a Mos hardness of 7.5. and an average particle size of 2 microns (producing high radiant re-emission).

 https://digitalfire.com/material/1725

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Yes, it was fire to sinter, which is interesting considering the amount of silica involved, but the silica is already bonded to the zirconium at the molecular level.

I'm surprised nobody mentioned how old this material is; I missed it the first time. Fortunately he is changing his site, so this much better formula has come to light. My apologies to all the guys who were trying to deal with the old one.

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I based most of my experimentation with ceramics on Mr Hansen's information. My ratios are close to what you refer to above. Bentone has the same role as veegum in ceramics but it is not the same stuff. I think close enough though. And it will be location dependent which is easily accessible.

Some of the parts I made with my mixture in are now in a forge which is awaiting first firing. I hope to update on that soon. 

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