Mikey98118

Those are all good points, Latticino. I would not call the thickness of the Kast-O-lite 30 layer a political football, but it is something of a tug-of-war

Yes; flame retention nozzles, whether flared or stepped, are only necessary, when a burner is being run outside of the forge; in other words, when the burner is being used as a kind of hand torch. Generally speaking, you want the burner aimed at the longest distance it can get, before impinging on internal surfaces; this can be further refined, depending on what you use for insulation within your forge. Most forges use ceramic wool insulation, with a 1/2" flame face of Kast-O-lite 30; in that case, you can position the burner low on one side, and aimed upward across the width of an oval or "D" shaped forge interior, so that it takes also takes the maximum distance possible before impinging on your work pieces. The longer combustion is going on before those gases can touch steel the more certain you can be that no single molecule of super heated oxygen will be in them. The advantage here is that you can tune your burner to a completely nuetral flame, without worry over scale buildup. With a lessor distance, you would need to tune your burner to a slightly reducing flame to avoid scale buildup. I would not recommend a 12" length, unless you are going to run two 1/2" burners, instead of one 3/4" burner, so that you can shut one burner off, and separate the internal area of the forge with a movable internal wall. Otherwise, you will be wasting fuel, during much of your forging. We usually suggest a two-gallon forge for a first effort. However, a used five-gallon propane cylinder will make you a lovely "D" shaped forge, by the simple expedient of raising its floor level under an extra thick base of insulation. I would suggest that your cut both ends of the cylinder off, and then reatach them with hinges on one side and a latch on the other; this allows you to accommodate the occasional large part, and makes all your internal construction work far simpler. You can look all the way through the Forges 101 thread and never find me recommending the use of Satanite on the interior of a forge. Use a 1/2" layer Kast-O-lite, and then a finish layer of Plistix 900, if you want to be thorough. And I still prefere to trap a high alumina kiln shelf in recesses cut into the end openings of a propane cylinder, over a pillowing layer of ceramic wool, for a highly effective forge, that is meant to move around to job sites, etc. However, just because one method is slick, does not make it the only game in town Morgan K26 insulating firebricks (use rated to 2600 F), and some other newer versions of insulating firebricks make very nice insulation, at a reasonable cost, too. Whatever method you choose will have particular advantages and limits (the kiln shelf can be slid in and out of the forge, for cleaning of welding flux. The insulating bricks are good to several hundred more degrees more than most ceramic wool, and are way cheaper than the ceramic wool in their own heat range). There is no need for confusion; look for the reason behind the choices. And before I get any flack back from this, remember that I said "necessary": I did not say "undesirable."

Note: Be careful not to mistake polishing wheels, which use silicone as their binding material, and very fine grit, with hard grinding wheels.

This may seem to be an odd way to put this problem, but it is the central issue. If you look at building a burner, step by step, they are all simple. If you look at the finish project as something new and daunting, your anxiety will confuse the issue. Surprisingly, the more we learn the harder it gets to remember how any subject looks to beginners

Note: Cast refractory burner heads (such as Giberson’s) appear to use Greencast 97 refractory (use rated to 3400°F), which gives a smoother casting than Kast-O-lite 30, even with vibration, but is nowhere near as crack resistant as the Kast-O-lite product. Greencast 97L, with alumina spheres included in its mixture (use rated to 3300°F), if combined with vibration during casting, might prove the key to a far better refractory block, than either one of the other choices.

Multi-flame burner nozzlees No discussion of flame retention nozzles would be complete without including multi-flame burner heads; the most popular choice of homemade multi-lame burner heads are ribbon burners, which consist of a brick shaped refractory block obtaining a large number of flame holes; this is trapped within a steel plenum chamber, which is screwed unto a burner’s mixing tube. Ribbon burners have become another “well-worn path.” However, ribbon burners are not necessarily the best path, as they are all large. What other multi-flame burner heads are there to choose from? Well, there is the Giberson 2" Mini-Square Giberson Head; an all ceramic plenum chamber and flame nozzle, which is designed to be screwed directly unto a burner's mixing tube (that ends in a pipe thread); this smaller size head has been around for several years. On the other hand, there are some guys who have made flame retention nozzles from a pipe reducer fitting, with a drilled stainless steel face plate; this creates multiple small flames. Giberson's ceramic burner heads are an extreme refinment, while pipe reducer fittings with drilled face plates are pretty basic; but, they both work the same way; creating multiple tiny flames, which slow down far faster than single large flames can; this allows exhaust speeds to be no greater than what is needed to expend the combustion gases; this keeps heat retention at maximum, since the greatest heat loss in this equipment is out the exhaust port. Giberson ceramic burner heads will outlast any stainless steel flame retention nozzles—only if handled carefully; these heads were invented to heat glass furnaces, which have slow ramp up speeds and long heating cycles. Use in a forge must be coupled with added care. If you just ramp up the heat in your forge as fast as possible, a broken burner head will be the result. Multi-flame retention nozzles, made from pipe reducer fittings will eventually oxidize away, when mounted in heating equipment; how long that takes, depends on the materials used in both the pipe fitting and its drilled face plate; you are best off to use stainless steel for both parts, and for the socket sets screws that hold the face plate in position within the pipe reducer. The face plate takes the most wear from high heat oxidation, and must be stainless steel. The end of the pipe reducer receives less where from oxidation, and should be stainless steel. The socket set screws will oxidize in place within a few heats, if they are made of mild steel; so they must be made of stainless steel, since the plate while probably need to be replaced every few months, when used daily. The thicker the face plate the longer it lasts, but the thicker the plate the more work it is to drill. You will want a think enough plate to rest stabile against the pipe fitting’s wall, trapped in place with the set screws. So, a 3/16” to ¼” thick plate, or flat bar should be your choice, to build this part from. Most of us do not have a lathe, so how do we shape the inside of the threaded pipe reducer to cradle the face plate in? Well, we use the internal thread as a handy guide; it provides all the indications needed to limit both depth and diameter of the face plate’s pocket, correctly enough to do for this purpose, when free hand grinding a pocket with a rotary stone, or wheel, in a rotary tool or die grinder. Rotary wheels ? Yes, aluminum oxide rotary grinding wheels kits, which come in two or three different grit grades, and are made to mount on 1/8” rotary spindles, are available through Amazon.com for about $7. The best feature of these wheels is that they are much more durable than wheel shaped rotary stones, because rotary stones are all inclined to break at their weakest point; this is where they are glued to the steel spindles. There are many grades of quality among rotary stones, depending on the material contained in their grit, and how they are glued together; but all of them have this same weak point. After you pay for the finest Dremel stone made of silicon Carbide, only to have its head break off just as easilly as the cheapest aluminum oxide stone, you will instantly understand to point of rotary wheels!

What other multi-flame burners would this be? Well, there is the Giberson 2" Mini-Square Giberson Head; a ceramic plenum chamber, which is designed to be screwed directly unto a burner's mixing tube that ends in a pipe thread, has been around for several years. On the other hand, there are guys on IFI who have posted photos of burners, with flame retention nozzles that are made from a pipe reducer fitting, with a drilled stainless steel face plate; this creates multiple small flames. Giberson's ceramic burner heads are on one end of the spectrum, while pipe reducer fittings with drilled face plates are at the other; they both work the same way.

At present, I believe that Chile Forge is the top-of-the-line forge offered for commercial work (for a slower pace, I would go with a single burner Diamondback, for their reliability). Do I think there is a better forge for doing commercial work than the largest Chile forge? No; but a properly built ribbon burner forge will get almost as hot with a smaller fuel bill, and should cost about one-sixth the money, plus some sweat equity, to build. Do I believe this is true across the board, size wise? No; at present, ribbon burners are most efficient in larger equipment; this may not hold true of other multi-flame burner designs. A gas forge made from a five-gallon propane cylinder is the smallest size I would heat with a ribbon burner, so it makes a good example to use, if we want to test the limits of ribbon burner superiority. Using two ½” high-speed tube burners, instead of a single ¾” burner, and a movable internal baffle wall, will allow this forge to equal the ribbon burner’s efficiency on small work, and that is as good as you can do; this isn’t a win against ribbon burners, but cuts your losses enough to extend how far single flame burners may compete with multi-flame burners. With smaller forge sizes, single flame burners, if well built, can hold their own. On the other hand, if you build a combination forge/casting furnace, a ribbon burner is impractical.

Yes and no, Tink; mostly you are correct. They have the same overall effect as that of slower flames; actually, they are every bit as fast as single large flames. The difference is that they slow down much faster than a single large flames can. Overall, I think that multi-flame burners are the future; however, before we get there, a lot more twists and turns are due to occur. For now, ribbon burners are probably the easiest way for most smiths to make a good forge. However, multi-flame burners were around, in other forms, for decades before ribbon burners arrived. Mikey

Ribbon burners do not have flame retention nozzles; they have a steel plenum chamber, with a multi-holed flame surface, which is made of a thick refractory layer. In other words, you still need to buy or build a gas burner to attach to the plenum chamber. However, since a little positive pressure is a good thing, with a multi-flame plenum chamber (but a bad thing with a single flame retention nozzle) you can employ a fan driven burner; these are much simpler to "get right" than most people think naturally aspirated burners are

Many others here are into ribbon burners; do not hesitate to keep them advised of your progress, and ask them for help.

That was a good one. Any more ideas floating around out there?

Working with castable refractory: Whatever castable refractory you use as a flame-face on the interior surfaces of your heating equipment, the finish product will turn out far smoother, if the casting is vibrated for a couple of minutes, after casting. Most refractories are packed in place, with a minimal amount of water, because excess water in the mixture weakens the final product. Vibration permits the refractory to move around like a liquid, filling in small voids, so that all surfaces end up smooth; this is especially helpful for castings with multiple internal holes, such as ribbon burner blocks. Home casting enthusiasts used to make their own casting vibrators; they posted several different kinds, but that was a quarter century back; my old brain no longer remembers much about them.

That is fine. Home casters used castable refractory with about one-third Perlite for insulation for years, and we ran out casting furnaces at yellow heat for about eight hours at a time on five gallons of propane. You could do even better with a ribbon burner. If you don't already have your refractory, Kast-O-lite 30 doesn't need the Perlite added to be very insulating, light weight, and crack resistant; it is what most guys use to make a ribbon burner. Whatever castable refractory you employ, a little vibration will greatly increase your pleasure with the finished product; especially how well a ribbon burner will turn out.

There is no advantage, whatsoever, in using a thick walled pipe. Most people end up using old out of date propane cylinders, or the even thinner Freon cylinders; nothing more is needed. I appreciate the desire to have an air/fuel hand torch out of the deal. But have your considered that any well designed burner can be used as a hand torch just as easily as for an equipment burner? Just saw your note about ribbon burners; I think they are a fine idea, but not for a really small forge; think five gallon container, if you want to heat the forge with a ribbon burner. Of course, that can be supplied by a five gallon paint can just as easily as with a five gallon propane cylinder Your thick wall pipe sounds just about the right length to be the center column of an anvil stand; that way its thick wall becomes useful; especially if it is filled with sound deadening sand.

Since you want to make knives, I will assume that you want a good forge size for that work. So, to begin with, somewhere between a 1-1/2 gallon to 2 gallon container will serve you best. You could even get away with a coffee-can forge (1 gallon size), for your purposes, but I think it would make you feel a little cramped. On the other hand, a two gallon forge size may be a little hard to get as hot as you want, using any kind of propane hand torch. By the way, I tried to look up the torch you mentioned, and all of the offerings were insufficient for your purposes; not that they are not large enough, but because the kind of flames they produce are not intense enough. Yellow flames are for burning weeds--not working steel. The kind of hand torch, or dual fuel torch-head from Amazon.com, which you need to do the job at all, tends to produce a hard blue flame. You will want to position a single burner in the center of whatever cylindrical shape you choose, or two smaller burners one-third of the way from each end of the cylinder. You will also want position the burner, or burners, just above the floor; aimed facing upward and inward, to create good swirl, while the hot gases travel the maximum distance possible, before impinging on your knife blades. Remember to make the burner portal hole(s) larger than the flame retention nozzle on your torch-head(s), so that the flame can induce secondary air past the nozzle to both cool it sufficiently to keep it from melting (if it is brass), and to finish combusting the fuel gas, which an air/fuel torch or torch-head will not do completely, because none of them are designed to do that. But, do not make the holes so large that a lot of secondary air will be induced by the flame, or you'll just waste fuel. I would give about 1/8" all the way around the nozzle for air induction. So make the hole diameter(s) 1/4" larger the the nozzle diameter(s). If I knew what you have for tools, and how timid you feel, I could refine and extend my advice to you. For instance, I suspect that you are avoiding burner construction for lack of tools, right?

I think the stuff from the Simond store on Amazon.com is consistently overpriced. However, to each his own.

The Hyper Tough 20V Max Brushless Cordless Cut-Off Tool is just like a 3” 12V angle grinder, but with nearly double the power of 12V tools; it is available, with a 1.5Ah Lithium-Ion battery and charger, from Walmart for $39.88. Battery adapters that allow Milwaukee 18V, or DeWalt 20V batteries to energize Hyper Tough tools are available through Amazon.com.

I agree with what all three have said. The only advice I would change is about "D" versus "tunnel" forges. While air tanks usually provide a natural choice as shells (bodies) for tunnel forges, and while all of us have been inclined to slice off the bottom of an air tank, or propane cylinder, when making a "D" forge, it is time that we all to stop, and ask ourselves why? It is easier to add a little more insulation in the bottom of a tube shape, raising up the resulting "floor," than to go through all the trouble to change the shape of the shell. Since this extra insulation can be thought of as tertiary, something cheap, such as Perlite can be used for it, with better insulation on top of this bottom layer There are only two sources for acceptable commercial burners, at present. The expensive source is Chile Forge, and they only sell 1" burners. The only cheap source for acceptable burners is Larry Zoeller Forge. You would like his "Z" burners. As to all the "also ran" junk burners for sale online, none of them has a designer behind them; they are all a collection of stolen ideas slapped together by fast buck artists; the problem with them, is that some of those ideas, were just plain wrong to begine with, while others don't work together; you know; kind of like mismatched socks In fact, you could buy a Diamondback forge, just to steal its burners, and be way ahead of the deal, as compared to buying an eBay burner. Finally, it seems odd to me that so many guys shy away from building sure and simple Frosty "T" burners, while planning on building a gas forge, which is quite a bit more work and expense.

Ramp the temperature up slowly, to begin with. Give time for whatever steam forms, to escape, rather than build up pressure. Just bring it up to red heat two or three times, before "going for it." I think you will be pleased with how well it works.

Isn't it great what some vibration does to smooth out a refractory casting

Thanks, Frosty. Any more of you people out there, willing to share?

One millimeter spheres should be okay. Perlite is fine, but you will probably want to finish coat the flame face with Plistix, to smooth its surface. Remember that a smooth surface radiates heat back into the equipment interior far better than a rough surface can; that is the genius of Plistix.

I remember back before the home our casting groups "discovered" Kast-O-30; they were using chicken wire in the hope that it would help keep our refractory together a little longer, after it started cracking. In those days, we all mixed Perlite into the refractory mix, to make insulating voids. So, the insulating, and lightening aspects of Kast-O-30 were no big deal to us, but its fracture resistance made it an instant hit Egad! That should read "our home casting groups" and "Kast-O-lite 30"...

I love hearing the private methods guys have come up with to do their work; spent decades dreaming up my own