Mikey98118

A good place to begin your search for an appropriate air/fuel commercial torch would be English manufacturers; they have been making air/fuel torches and burners for a very long time. Otherwise, you'd best figure on building a burner.

Understood, and agreed with

Except for those little twisters that you can create inside your burner

Yery good design work. However, you should consider a straight and parallel tunnel for your flame retention area. Otherwise, you are likely to end up getting back fires into the burner's mixing tube. Also, you would be better off raising the angle of the burner, and tunnel so that the flame is sure to miss impinging on the work, but more importantly to assure that there is no chimney effect after shutdown. Yes, a 1/2" should get this forge to welding heat. Yes, the exhaust opening's width is a plus, and I would suggest movable bricks for your baffle wall, rather than any forge door on this design. Thank you for posting such a fine drawing

Good point, and counterpoint. I always use needle valves on my high velocity burners; but is for fine control at my fingertips, rather than necessity. Regulators are all that is necessary; needle valves are just a luxury

And so we come back to the often disputed question of whether and how much altitude affects these burners. I think the ayes have it. But I also think it takes a lot more altitude than people worry about.

I agree with with this man's application being as safe an answer as there is likely to come along. I also agree that safety codes must be followed. However, I doubt that the code applies to this particular case, because the heat source is controlled. Furthermore, I paid for a copy of the code twenty years ago, and this subject was not mentioned in it then; I doubt that it is now.

By "trimming" did you mean "adjusting for" altitude? I'm not trying to be picky (this time :-). "T" burners are tuned by trimming back their MIG contact tip's lengths.

Or, they can stick with a plastic air chamber, and avoid some of those steps. If the burner is handled carefully, I don't see that as a problem. Not that some idiot won't make it a problem, sooner or later. The fans on my induced vortex burners, are also plastic, so I think about this stuff.

I recomend a MIG contact tip for 0.025 welding wire as the gas orifice in a Mikey 3/4" burner; that has an orifice diameter of 0.034". The amount of gas a burner puts out is controlled by the gas orifice diameter times the gas pressure. A Frosty "T" burners use a little larger orifice diameter and lower gas pressures.

They are supposed to restrict flow; that is the very idea. Understand that a 1/4" valve, ball or otherwise, produces WAY more flow than is needed. The final gas orifice sizes are given in thousandths of and inch!

h for anything smoldering in a corner or under a bench. Regulators and fuel hoses There is a lot to know about hoses, different kinds of valves, and other plumbing choices (black hose versus, copper tubing, versus stainless steel braided gas hose, etc.), but, so long as you think about safety FIRST, and avoid doing something thoughtless, all those choices are only about what I call "add-ons." Meaning they can be rearranged at your leisure, giving lots of time to learn the fine points about plumbing your equipment before making a final decision. For instance; should you install an idler circuit? That is best done with metal tubing or pipe--not rubber hose. I personally dislike using copper refrigeration tubing to plumb gas equipment; but there is nothing half as good to employ in an idler circuit. We must beware, not to trip over our “druthers.” The first piece of equipment attached to your fuel cylinder should be a variable pressure regulator. You cannot use acetylene regulators for any other fuel gas; they are illegal, unsafe, and impractical to use with LPG fuels. While you can use a typical multi-fuel gas industrial regulator, LPG regulators are less expensive and better suited for use with these fuels in cold weather. I recommend using a 0 to 30 PSI model, with a pressure gauge attached, although a 0-20 PSI regulator will serve just fine, most of the time. You can find good quality 0-30 PSI propane regulators offered on eBay, Amazon.com, or find them locally at large hardware stores. If you end up with a regulator that does not have a pressure gauge, or a side port in which to install one, you can add a “T” pipe fitting at the regulator’s outlet and install a pressure gauge there, using 1/4” short pipe nipples; one for the gauge and one for the gas hose. Caution: NEVER attempt to use water hose, or air hose, to carry fuel gas. Propane can partially dissolve the hose and/or seals on water and air fittings. The first you now of it, may be when the entire hose is suddenly ablaze (I was present when this happened to a friend). D. O. T cylinders are usually fitted to regular high-pressure black propane appliance hose; this is available with various fitting choices from hardware and appliance stores; I do not recommend it. Appliance hose is stiff (difficult to work with), overpriced, and seldom comes in twenty-foot lengths. Instead, I recommend using regular 1/4” size “T” (multiple fuel grade) twin torch hose in standard lengths. Once you buy the hose, remove the brass guards from both of its ends, and simply pull the red fuel hose away from the green oxygen hose (save that oxygen hose). What you end up with is a highly flexible top-grade fuel hose at a reasonable price, which can be found at any local welding supply store or ordered online. Take care not to end up with oxyacetylene torch hose; it must not be used with LPG fuels. Stainless-steel braided fuel hose is steadily decreasing in cost, making them a bargain priced safety item to add between the rest of your fuel hose and the last few feet near heating equipment; or for a few feet between an outdoor fuel cylinder, and a through the wall piping system (or indoor section of hose).

The 2-1/2 gallon "D" forge Another variant on two-gallon tunnel forges is a two and a half gallon forge, shaped like a “D” laying on its side; these are made from the top half of a five-gallon propane cylinder, cut lengthwise; this half has an exhaust opening cut into its front, is lined with refractory, and rests on a steel pan, which is filled with various refractory layers. Where and what kind of burner or burners will be mounted varies from builder to builder. A narrow ribbon burner can even be mounted in one side of the base pan, rather than burners in the half cylinder top portion of these forges.

Speaking of stuff. I figure you have more good ideas for stuff. We need to encourage you to cough up more of them wild thoughts floatin' 'round in your head

Another limitation in forge/furnace design is burner positioning. While the flame can be pointed in several ways in a forge, the flame in a casting furnace is aimed to impinge on the furnace wall as far forward as possible, without directly impinging on the crucible (since this promotes early crucible failure). If the flames in a forge were aimed this way, they would not burn for a long enough distance before impinging on work pieces, if the burner(s) should be pointed downward, toward the floor area. In these days of greatly improved refractories, it is better to aim them upward and slightly inward, to ensure the longest possible exhaust path in most forges; the exception being forges designed to create a hot spot, but there always are some limitations

I agree in principle. But, pushing the envelope is just sooo Mikey

Further details on C-c forges The main difference between a tube forge and a casting furnace is that the forge is positioned horizontally, and the furnace is vertical. With a little added work on its legs, and the addition of an emergency drain hole at the bottom to let liquid metal escape into a metal sand box (in case of crucible failure), a forge, with a locking hinged door, can be made to do both tasks well enough. One of the hard facts of equipment design is that there is no free lunch. Everything is a tradeoff. Being able to cast and forge in one piece of equipment must be paid for with some limitations on what can be done with the door and the floor, the larger the forge, the more serious these limitations become, but in a coffee-can forge/furnace the limitations are minor, because its capacity to heat work pieces for forging was minor to begin with.

Given propane for your fuel, or LPG (mostly propane/butane mixtures), and given a burner that is a good enough design to make a neutral flame: Then a 3/4" pipe size burner will heat a properly constructed 350 cubic inch forge (five-gallon cylinder) up to welding temperature. For every reduction in pipe size, divide the cubic inches in half. For every increase in pipe size, multiply the cubic inches by two. A mini-forge is two-gallon equivalent, so one 1/2" burner, or two 1/4" burners will more than do the trick. Nevertheless, I would advise you to use two 3/8" burners, and simply run them at lower fuel pressures. Naturally aspirated burners have long turn down ranges, so let them loaf along. So, why not choose 1/4" burners? Because 3/8 burners are a lot easier to construct; that's why!

Good forge designs have reached 2750 F, with an excellent burner. I believe 3000 F, when burning propane would be epic. However it only takes a good design to reach 3000 F, burning propylene.

Good, good. There is always plenty of room down at the deep end of the people's pool

Good!!! Most people are in such a hurry to build their first forge, that they have it half built before the realization sets in, that they didn't have a solid plan. And now they wish they had done this, and they wish they hadn't done that...it's kind of sad. You stated that you " have all the stainless sheets for the enclosure." I like that you chose stainless steel for your forge's enclosure (we usually just call that a "shell"). I hope that you are going to make that enclosure's shape worth the effort. As I recall, you were looking to build a min-forge (about two-gallon size). But, what shape? Box or tunnel forges are the simple choice, but oval shapes give you more usable area, which increases in importance as equipment. But, "D" shape forges share this same advantage with oval forges, and are a lot easier to build. Whacha think? Should read "...which increases in importance as equipment size shrinks."

Carbon fiber can withstand 3632 °F (2000 °C) in the absence of oxygen. So, carbon fiber could be a great way to strengthen refractory bodies, so long as both their inside and outside surfaces are carefully sealed.

Mounting burner ports: Typically, a burner port (entrance) consists of a short steel tube or pipe with about 1/4” larger inside diameter than the burner’s flame retention nozzle’s outside diameter. This allows enough space to aim the burner somewhat within the portal. The burner is held in position and aimed with two rows of thumbscrews; each row has three equidistant screws. One of the advantages of these screws is that they can hold a pipe or tube in place within the portal, and resting exactly where the flame is intended to impinge, while the portal opening is being ground into an oblong shape (to allow the tube to be aimed at a desired angle). This method ends up with a very close fit between tube and shell opening, to promote easy silver brazing of the port’s tube to the equipment shell. You are building a burner, so why not employ it to help you construct its forge? Alternatively, you can drill and mount a burner port in the shell with three bent flat bars and some pop rivets, or self-drilling screws. Bracketing parts together can end up looking tacky if you do not manage to keep the shell opening tolerances close. Employing screwed brackets can be a be a minor pain, if the burner’s port tube is positioned at an angle. Welding equipment parts, such as burner ports unto a steel shell, takes a wire feed machine and a learning curve. Some people are reworded with distortion in the shell, because of welding contraction; it only takes a little time to learn to run a wire feed welder, and somewhat more to bridge gaps with one; but it takes a lot more time to learn where and how much to weld without creating distortion. Neither brazing, or silver brazing makes that problem. Hard brazing requires an oxy/fuel torch, or an air/fuel torch, propylene fuel, and a lot of skill, Silver brazing can be done with an air/fuel torch, propane, and close attention to setup, but most silver brazing alloys won’t bridge gaps very easily. However, some silver soldering alloys do bridge gaps. Silver brazing by hand torch benefits from a lower temperature filler with broad melting range such as Ufhauser silver braze filler A-54N (54% silver/ ) that has a broad elastic range (250 °F), and bridges minor gaps; it can be considered a capping alloy, but if heated too slowly it can suffer from liquation (where the alloy separates into solid and liquid zones); it will melt between 1325 °F (dark red) and 1575 °F (bright red). The high temperature portion will melt only above the normal brazing temperature afterward. For this reason, alloy A-54N should be heated rapidly through its melting range. If you are joining a thin shell from a tin can to a thicker tube, keep the flame mostly on the tube. This filler alloy has a good color match to steel. Reasonable care with a sanding drum or grinding stone in a die grinder or electric rotary tool, will easily produce a sufficiently close-fit in the joint between a burner portal tube and the forge shell opening. If you’re silver brazing on stainless steel, burn polypropylene fuel gas (if you employ an air/fuel torch), and a high temperature black flux. Car mufflers are zinc coated, and silver brazing parts to this kind of forge shell will ensure lots of damage to the plating. Stay Brite silver solder may be employed afterward, if you don’t want to paint the forge shell. Most zinc-based soldering alloys are zinc-tin-lead (avoid these), zinc-tin-copper (excellent), or zinc-cadmium (use fume rated respirator with these and follow all safety guidelines to the letter). Note: The main ingredient in zinc flux is zinc chloride (follow safety guidelines on container); it is the only ingredient in many of them; it tends to “tin” the surface of steel, rather than just cleaning it. If steel is freshly cleaned and power buffed with stainless steel wire wheels, it can be zinc soldered without flux, but why do things the hard way? Zinc’s melting point is 787 °F; comfortably below its boiling point (1665 °F). Zinc fumes are easily seen and smelled; avoid them. Unlike lead fumes, it takes a heavier dose of zinc vapors to cause fume fever. Unlike lead, the body can tolerate a little zinc, but keep your dose tiny; none is best. No metal fumes are good for your lungs. Caution: Metals give off toxic fumes upon reaching their boiling points. Using zinc coated sheet metal or parts (such as car mufflers) is okay if you're careful about doing it. The boiling temperature of zinc (the point at which it makes fumes) is 1665 °F (bright red heat). Your forge shell should not get higher than one-fourth that temperature. But you do need to be careful to keep the shell well away from the edge of the exhaust openings, by not making the openings in ceramic fiber, kiln shelf, or cast refractory even with, or even near the shell. Zinc coated flame retention nozzles or mixing tubes are out. There is no reason at all to avoid zinc coated reducer fittings on a burner’s air openings. In other words, keep zinc away from part surfaces that may become incandescent (above 1200 °F or 649 °C). Note: Preheat temperatures should be kept down to 600 °F (315 °C on zinc coated surfaces, such as car mufflers, to avoid damage to the existing coating on their surfaces, and to keep scale formation down on the steel; “tinning” the bare steel with a zinc chloride-based flux will help with this. Remove all residual flux with hot water and a clean rag after soldering. Larry Zoeller (of Larry Zoeller Forge) is credited for first mounting schedule #40 pipe to a forge shell with conduit locking rings; he calls it a “burner holder assembly.” If you’re looking for fast and easy, he sells them for $25 and shipping from his website. Their main limitation is that they can only be positioned at right angles. The burner port’s tube should be completely external to the forge shell; it should not extend inside the forge further than is needed to secure a locking ring. A washer should be provided to slide up and down the burner’s mixing tube above the portal, so that it can limit how much secondary air the burner flame can induce through the gap between the burner’s mixing tube and the portal wall. A nut can be silver brazed onto the washer, so that a thumbscrew can keep it positioned at the right distance away from the portal edge; limiting secondary air into the forge to only what is needed for complete combustion, without lowering internal temperatures needlessly. To consider air introduced from the burner opening as no different than air from other openings is a sad mistake, since those other openings don’t have flames inducing air into the equipment.

Air Chokes are a burner’s secondary control For several years there were two very good reasons for adding chokes on burners; the first being to prevent chimney effects from overheating burners after shutdown, and the second was to vary flame characteristics. As gas burners have grown more intense, using chokes to alter flame characteristics has diminished; the technique still works, but is less appealing than it was in the past. Burner chokes greatly diminish chimney effects from traveling up through the burner after shutdown, but might require a secondary control mechanism (such as a moving washer on the burner's mixing tube), to stop it from overheating from air rising between the burner and its portal; this is especially true of burners with electrical fans. This washer can also serve to control excess secondary air induction, created by the flame, from lowering forge temperatures, while the burner is running. Caution: Never trust an external washer to stop flames from backing up from the forge interior, and overheating the burner; this is the equivalent of using a bandage, when a wound needs stitches. The flame is pushing into the burner portal because of back pressure in the forge. You need to address the problem BEFORE YOU BURN DOWN YOUR SHOP! You may simply need to enlarge the exhaust opening in your forge, or you may have too large, and/or too many, or even too weak burners, mounted in your forge.

What size burners, and what size furnace?