Mikey98118

Sealing and high-emissive coatings for ceramic fibers and other surfaces Rigidized ceramic fiber products still need to be sealed for safety. Furthermore the various coatings used for sealing tend to create a tough surface layer that holds high-emissive coatings from peeling away from the fiber’s surface; an irritating tendency that results from spreading high-emissive coatings directly on fiber products (especially those that aren’t even rigidized). Just as not all sealants are rated as high-emissive, not all high-emissive coating are sealants, so we need to review the better known products: ITC-100 is strictly a high-emissive coating; I have found that deliberately separating it by adding more water to small amounts in a water glass, causes the non-colloidal particles to separate out, refining the coating, and greatly increasing its emission of radiant energy. For less money than this product now costs, 100% colloidal zirconium can be purchased from various lab suppliers, and mixed with phosphoric acid from your groceries store, to make a high-emissive coating rated above 90% “reflective” of radiant heat. Frosty and others on this group concoct a tough sealant coating that is also a high-emissive product; you get the zirconium silicate flour for it from Seattle Pottery Supply (or other pottery suppliers), and mix it down with clay powder; ask them for particulars. Zirconium silicate, while very tough is only rated at about 70% “heat reflective,” but I think this figure is misleading; since the other part of its structure is clear natural crystal, which will pass light rays with very little interference, and since the actual mechanism for its “heat reflection” is re-radiance, I believe its overall performance in thicker layers will prove to be considerably higher than 70%; it is also very resistant to borax, and an economical choice. Plistix 900 has 70% heat reflection, and makes a tough smooth sealing coat rated for use at 3400°F. Matrikote 90 AC Ceramic Coating (one of the product line from Allied Minerals) is a very tough hard coating containing 90.4% alumina, 1.5 silicon dioxide as a vitreous(glass-like) binder, and 2.7 % phosphorus oxide as a polymerizing binder. Matrikote is good to 3000°F, and would prove especially useful as an inner layer between outer coatings of higher use temperatures and rigidized ceramic fiber products. There are other bonding mortars and high temp coatings. Probably the best known refractory mortar for use for hard coating ceramic fiber blanket is Satanite; it is use rated at 3200 F, and easily purchased in small quantities through knife making suppliers on the Net.

One of the things I noticed about tungsten carbide rotary files, is that the larger their diameters are the further they fling those needles. Over time, I came to stick with 1/8" diameter files, whenever possible.

Caution: Tungsten carbide rotary files fling tiny needle-sharp slivers. You need to wear goggles, or at least glasses, for eye protection. You are also advised to wear long rubber dish-washing gloves, or a rain coat with latex gloves, to keep them out of your skin and clothing. Immediately after use, remove and shake out dish-washing gloves and rain coat. Discard latex gloves. Sweep away the slivers from parts and equipment surfaces, with a brush.

It will give you all of that. More to the point, it will awaken your appetite for gas forging; this is why you want to hold on to the other forge parts. Yet, no matter what other forges you buy or build, that first small forge will remain you preferred tool, because it costs the least to run, and doesn't over heat your shop in "the good old summer time."

At this point, I can only suggest that you drill two of three 1/8" diameter holes in the bottom of the forge shell, and slowly heat the forge for a few minutes at a time, to turn all that water trapped under the hard refractory layer safely to steam; otherwise, there will be cracking or worse (steam explosion), during the forced drying of the Kast-O-lite.

Mounting a homemade side handle: Rotary tools and die grinders can be braced for straight travel (like surface cutting with angle grinders), rather than the typical swinging arm motion (tendency to curve, binding the disc, resulting in kickback), by mounting a side handle near to the tool’s spindle; this provides greatly improved control. Twenty years ago, 2” angle grinders like Proxxon’s Long Neck Angle Grinder, or the Merlin 2 from King Arthur Tools, were the only electric tools that could easily make straight line cuts in small burner parts; they were designed for inline motion, and had steel safety guards. A rotary tool with a safety handle mounted can now do a better job, more safely, for a small fraction of their prices. What has changed, to make this possible? See-through safety guards couldn’t be purchased back then; they can be now. When cutting along an ink or scribe line, it is tempting to bend over the tool, to provide an adequate view; a very bad habit, unless the tool has a safety guard; it’s also frustrating to try to see the cut line by peering around steel guards. But you can place your disc right beside the cut line, and work in safety and comfort, when you see the line by looking through the guard. Some rotary tools already have a removable plastic handle, but they are set up at about seventy-degrees for increased comfort during buffing, grinding, and drilling work; not at right angles, for better control during a surface cut. Most hand-held rotary tools have a threaded plastic neck area around the base of the spindle. This threaded neck is 17mm diameter protruding from the plastic housing’s shoulder; this is the area that a sheet metal side handle can set in, trapped between a plastic shield, or just the original plastic threaded colloar, and the tool housing’s shoulder. Dremel popularized those same threads to securely mount attachments, such as their flexible drive shaft. Then, other manufacturers copied Dremel. The threads on safety shields are 17mm (0.670”). It is easy to buy a 3/4” flat washer. A flattened tube end can be welded, or brazed to the washer, creating a similar kind of handle as the ones that provide ergonomic stability to angle grinders. Or, you can layout a washer and handle shape on a piece of sheet metal, and employ your rotary tool to fashion a side handle; this allows the use of aluminum, stainless-steel, or brass sheet metal, which will never rust or need painting. A plastic rotary shield, or original threaded collar, securely traps it in place, when needed; or it can be quickly removed, when it would be in the way (during drilling, and some grinding tasks). It should prove very helpful during beveling with tungsten carbide rotary files. Why bother? Because a swinging wrist movement can’t be braced anywhere near as effectively as inline movement (which only becomes practical with the aid of this side handle). Where the handle is positioned has nothing to do with whether you are right or left-handed, and everything to do with moving the cut-off disc opposite to the direction that the disc is trying to force the tool to travel along part surfaces. You need the handle to help tow—never push—a cutoff disc forward along the cut line, once it starts to break through the kerf. A side handle helps the disc to grind a straight line through the material from the formation of a groove through to the end of the cut, greatly reducing kickbacks; especially when dealing with the last fraction of an inch at the end of a line. Best procedure is to run the disc back and forth on the part’s surface, while a groove forms and gradually deepens, cutting through the part only at the very end of the process; this means that increased control of your arm movement, becomes more essential—not less. Warning: The main point of a side handle is to help in surface cutting with cutoff discs, or when beveling with a tungsten carbide rotary file. But cutting and beveling with an electric die grinder must be done much more carefully, than with a rotary tool. (1) Cutting safety also requires a power switch with the right location and type. The switch must be easy to shut off, without jiggling the tool, in the slightest degree. Movement while turning the tool on doesn’t matter, since that is always to be done before touching the work. (2) A full-power die grinder (400 to 550 watts) must be run at half speed during surface cuts. A medium-power die grinder (220 to 280 watts) can be run at full speed. (3) The cutoff disc should not be larger than 1-1/2” diameter; smaller is safer. Take your time working up to the fastest speed, and largest disk, that you personally can safely use. (4) The disc must be breakable; a resin-based friction disc; and thinner is safer than thicker; it is not less likely to break of course, but will be that much less likely to fling the grinder about while doing so. Do not employ a grit coated steel disc, or a toothed circular saw blade, even in a medium-power electric die grinder. When kickback occurs, it is necessary that the accessory be destroyed, rather than the grinder being savagely flung about near your body. Do not kid yourself that you will always avoid kickback; that is not in the cards. (5) A die grinder should not be used for surface cutting in confined spaces, or with your body unable to be properly braced, with or without a handle installed. If you must cut in a confined space, use a 15/16” friction disc, on a rotary tool (nothing with more torque); better safe than sorry. Safety, is seldom an absolute, except in the negative sense. “don’t ever do that” is clear and simple advice. To suggest that someone “do that safely,” is absurd. Whenever you attempt to do anything, some risk is involved. Using an electric die grinder, can never be perfectly safe; cutting with one can involve substantial risk; especially if safety procedures are not observed. Why not use one of the new mini-saws, instead; isn’t that what they’re for? If you are cutting on flat surfaces, yes. If you are cutting off the ends of angles or pipes, the saw still maintains an advantage, so long as you pay close attention. When cutting into pipe or tubing, no. If you are cutting into curved surfaces on cylinder ends, to create equipment shells, no. When grinding, sanding, or wire brushing with a die grinder, there are safer choices too. A brush shape is generally safer than a cup shape, which is usually safer than a wire wheel, because with every change of shape the accessory’s diameter tends to increase. A diamond coated burr is the least likely accessory to generate kickback, followed by a stone burr. Solid tungsten carbide burrs are most likely to create kickback; of these, double cut burrs will create stronger kickback than single cut burrs (of the kind meant for steel work; not the large grooved burs used on aluminum, brass, and wood. And of course, the larger a brush, burr, stone, or sanding drum’s diameter the harder any kickback will be. The stronger the tool’s torque the harder its kickback. The higher the RPM the harder the kickback.

The limit on turn-down range for that burner is just above 4 pounds per square inch gauge pressure. At 4 P.S.I. it begins to huff, as the flame starts burning back into the mixing chamber. If allowed to continue, the mixing chamber begins overheating and the huffs become bangs; finally, the flame is blown out.

As good as brick pile forges have become, thanks to tremendous steps forward in the tougher insulating bricks available now, and advances in flame coatings to protect their surfaces, and also in available burners, I wouldn't be surprised if brick pile forges become the standard forge for novice builders. I will probably have to build one, just to keep from being utterly left behind by progress Don't worry, Frosty. You can depend on me to complicate it to the max. Lets see... we can start with an elongated hexagon...

You have it right. There is precious little worth knowing, that comes aside from experience. And probably first on the list, is knowing what you want.

Good morning Frosty

Why does a little alarm bell ring in my head, while reading this? Because it fits the facts. So, how do they check for this, and what can they do to fix it? By hooking up the burner intake to a water hose, and then turning on the faucet, a jet of water should spurt out of the burner's end; it is supposed to be dead center I expect that it will be canted well off center, showing that the gas orifice is badly misaligned. If this is what is shown, than only being able to align the gas orifice in the cross pipe will sold the burner's problems.

Aside from some blade-smiths, or jewelers looking to forge tools in them, just about everyone who starts out with a small gas forge, ends up wanting (not necessarily needing) a larger gas forge. So, my advice would be to hold unto this good-beginning-of-a-forge, for when your ambition grows. Go ahead and buy that small gas forge, so long as it is a Mr. Volcano forge; the rest of them can always be used for parts, but not necessarily used "as is." Why would that be a good idea? What you said about buying a gas forge for small bucks only holds true for very small gas forges, and only then if you make the right choice. Larger forges come at premium prices; there are no bargains in that market!

I believe that they have changed their burners over the last few years. When we give people advice on this group, it is only about how to get the best performance from their equipment, versus what they are able to do. Manufacturers must balance other factors, like sales appeal, and production costs. If you need better performance than you are getting, spend time looking over burner design... Or, if you're looking for a practical solution, replace that burner with a Mr. Volcano burner; they only cost $25. You couldn't even buy the materials they are made from for that price

Where you are, and with your background, I would advise that you simply build two of Frosty's "T" burners, and continue on with turning that good beginning into a completed gas forge; you will never turn back, and your coal forge will end up collecting dust in a corner.

So, if he ran a piece of sheet metal across the front and back openings at the same height as the bricks, and a sheet across the bottom, he could merge both ideas, and fill in the pan thus created. That still leaves him needing to mount a burner or burners...

You have a good start on a forge there, but it needs some finishing touches. The arched top half of a "D" forge is present, and seems to be well made, but its insulation needs to be protected with a flame face, after it is rigidized. From the photo, it appears that there is a gap between two insulating bricks, which will need to be filled in, unless that is where the burner is supposed to go. About the burner...it's just junk. You need to replace it with a $25 3/4" burner from Mister volcano, before they come to their senses and raise prices. I purchased one of them a couple months back, and they are a fabulous deal. The gas regulator looks to be pretty good quality, so keep that. Finally, you should look around to find, or build a steel or stainless steel rectangular pan to set the top half of that forge on. Somthing deep enough to allow most of its area to be filled up with Perlite secondary insulation from the garden department of your local hardware store. Use Morgan K26 insulating bricks, or ceramic fiber board over the Perlite, and spread a 1/2" layer of Kast-O-lite 30 over that for a flame face. Use bricks-even plain old hard firebricks- to stack as a movable wall against the back opening of the forge. And use bricks stacked 1" away from the front opening, as a movable baffle wall to push parts through. Of course, following all this advice takes time and money, but you can limp along with the forge, as is, while you make these improvements. Changing out the burner will pay for itself in about 16 hours run time.

Gas Assemblies for Free-flow Burners It has been well established that the gas tube, and whatever MIG contact tip, or 3D printer nozzle is used as a gas orifice, should be centered with, and aimed parallel to the axis of a linear burner’s conical air entrance; and that this funnel shape must be centered on, and kept parallel to the mixing tube’s axis, by whatever means is convenient. But how you choose to mount the gas tube, is your first and best chance, to create an intense burner flame; do not waste it! Why such emphases on a “minor” detail? Your burner has an energy budget; it is limited to the air induction that the fuel gas jet creates via Bernoulli’s Principle; this is a naturally aspirated burner's engine. The least obstruction to incoming air, will subtract the least energy from your gas jet’s small output; this is an important factor to consider. As with the whirlpool in your bathtub drain, nearly all air is going to be induced near the conical opening’s periphery. No significant air will move down the center of the entrance. So what? So, this tells you just where obstruction impedes air most—and where it does not. The smaller your burner’s air intake diameter the more this factor matters. Finally, it takes energy to get incoming air moving, or to change that air’s direction, to create swirl. Any blade structure at the air funnel’s opening, starts incoming air moving laterally, instead that starting within the funnel, where it costs more energy. Mounting a gas assembly has two aspects; what is easiest and what works best. There will be no "perfect” method of balancing these factors, because aside from tooling and skill levels, we all have task preferences; mine is for maximum control of the parts being assembled, having found that the best results for the least work is attained, if Murphy’s law never gets the chance to muck anything up. Gas assemblies for free-flow burners are best mounted by suspending them in mounting plates made from fender washers, of up to 2” diameter; keeping your labor at a minimum, by requiring only part of the work needed, to create a mounting plate from scratch. For larger openings than 2” you must lay out the plate with dividers, on sheet metal. So, why start with sheet metal, or a fender washer to make a mounting plate? Why not braze, or weld the separate parts together instead? When you begin with a flat surface; all you need do, is avoid bending it, to assure that the gas assembly mounted to it will remain in line with the axis of the conical shaped air opening Fender washers come in various thicknesses, over which you have little control; because they all have 2” or smaller diameters, that is okay. But the larger mounting plates that you make from sheet metal need a minimum thickness, to ensure that they stay flat during construction, and installation. A 0.079” thickness in stainless-steel sheet is strong enough to remain straight, while being screwed or silver brazed to a funnel’s flange, but not so thick that it is difficult to drill holes and cut air openings in. How thick aluminum sheet should be is more dependent on what alloy is used, rather than funnel diameter. Choose 1/8” thick 6061 (AKA T651) aluminum plate; it is the most rigid aluminum alloy available, but is no more work to drill, thread, or cut, than a soft aluminum alloy. Use dividers, and a prick punch, to lay out a disc of the same size as the outside diameter of the funnel’s flange, or ink a line on the sheet metal, using the flange as a model, and use a cheap plastic center finder to mark a place to drill a center hole in it. Note: Small metric (ex. M2) cap screws and matching nuts are the inexpensive and simple way to screw mounting plates to smaller funnel flanges; they allow you to drill matching holes through both parts and use nuts to hold them together, while avoiding the use of tiny taps (which are inclined to break off in the hole). You can find them in kits for under ten dollars online. Drill an oversize hole through both parts (use 1/8” M35 high speed steel drill bits for M2 size screws). If the flange has room enough, using 10-32 cap screws will save on tool costs. Drill a hole in the middle of the disc for a Rivnut (a threaded rivet nut); this holds an externally threaded gas pipe, which can be moved back and forth in the funnel, as part of the tuning process. The rivet nut is pushed into the washer, for silver brazing, silver soldering, or for setting in place (physically trapping by deformation). Mark out three equal spaces for air openings, between three ribs, using a divider (or just use the points of a hex bolt and plastic center finder to indicate where they should be). Drill holes between the the ribs, comfortably outside the area of the nut, and cut between them. Remember that there is no significant air flow in this central part of the opening, so do not shortchange yourself on rib width in this area. The ribs would be too weak, if you kept their lines parallel; that is not desirable. You want the three ribs narrower at their outer ends, and becoming wider toward the center of your disc, to balance maximum air induction with sufficient inflexibility. If you use a silver braze alloy with as high a melting range as you can find, along with black flux (which is rated for stainless-steel), it will provide a high temperature bond that requires less care to keep a brazed rivet nut in place, while brazing the ends of the mounting plate’s three ribs onto a funnel flange, with easy flow silver brazing wire and a lower temperature rated white flux (but still rated for stainless steel). Water-soaked rags, or blocking putty (ex. Wetrag) around the rivet nut, but kept away from the second area being joined, is another way to help protect existing silver brazed joints. Anti-flux can be placed around a joined area that is too close to the new joint for blocking putty to be used effectively; by resisting fluid flow out of the area of an existing joint, it will help you to protect it, when brazing a second joint, if you waste no time. Drilling and threading brass gas tubes: Most brass tubes and pipe fittings that you will buy and turn into burner parts are half-hard brass; this can be drilled and threaded more easily than stainless-steel alloys; however, it can be tricky to tap threads into, or run a die down; it tends to gum up tool edges on dies and taps. Half-hard brass alloys are inclined to compress during threading; this is a form of work hardening. Tapping fluid should be employed during threading; it can be purchased in amounts smaller than a pint). Even cooking oil is better than dry threading. Internal thread: Always tap the internal thread for whatever part you employ as a gas orifice first. Cut the external thread second. Tubing sizes may be a little small inside; in that case use the recommended drill size to enlarge it before running internal thread with a tap. If the tube is a few thousandths oversize, that is okay. Many novices lack a drill press, and see no use for one; they will be tempted to drill and thread by hand. However, a cheap drill press vice is only about ten dollars, and by placing your parts in the vice before you try hand drilling or threading with a tap, you will stay parallel with the tubing axis, far more easily (trapping your tube in the vice will also help you to correctly start a die down its exterior). Start threading with your tap as perpendicular as possible, and only turn the tap until you can feel resistance suddenly increase (the “quarter- turn and reverse tool to break burr” rule of thumb is not adequate for half-hard brass; instead, you must back off the tap as soon as you feel a sudden increase in resistance to movement. It does not matter how little progress you make before breaking the burr away from the thread end, and starting another twist; have the patience to follow this advice. You are going to be using small (and therefore easily broken) taps of M6x1 or ¼-27 and in size. Also back off the tap every full turn forward, and run it back over the thread you just made to clear burrs, and smooth up the new thread; otherwise, after a few extra twists, so much pressure will be needed to do this, that small taps will break off in the hole, as you attempt to back them out. Be liberal with your tapping oil. Dealing with a broken tap is no fun. Should you break a tap off in the tube, gently tap back and forth on its protruding point, to loosen it in the hole; then, try to back it out with pliers; if that does not work, cut away that section of tube, and try again with a new tap. You should have no need to use a drill bit inside 5/16”x3/16” brass tubing, unless your tubing isn’t actually 3/16” inside diameter; that is not very likely, but these are usually imported parts; you are probably going to be dealing with an ignorant drop- shipper (meaning they “don’t know or care” about actual sizes). External thread: Use the same care when threading with dies as with taps. Dies usually have their description written on the opposite side that is meant to face the work. Be careful to mount the die facing correctly, and grind a bevel on the tube’s end, to help get it started threading at true right angles; if you start the die threading close enough to perpendicular to the tube, it will finish truing itself up, within a twist or two. If the tube is a few thousandths small on the outside, that is okay. If the tube is the slightest amount oversize, your die will have far more work to do; spin the tube in a drill motor, and sand that extra diameter down to size; especially when running coarse thread, like 5/16-18. The coarser the thread the harder it is to run. But the courser the thread the less of it that needs to make contact. 75% contact may be needed in a fine thread, while 50% contact will work just as well in a coarse thread. Even the same outside diameter as the die can be hard to work with. If the first half-inch of thread is difficult to run, consider deliberately sanding the rest of the tube’s length a few thousandths of an inch undersize. Full contact in the first half-inch (at the tube’s end) helps to secure a gas tight joint with a hose fitting, but it is not needed (or especially desirable) on the rest of the gas tube. So why work that hard? After cutting the external thread, chase it thoroughly. Run the die back and forth over the new thread, until it moves easily. Otherwise, this part of your burner will be difficult to adjust for fine tuning. 5/16-18 screw-on flat mounting T-nuts can be reshaped and silver brazed, or silver soldered directly onto small funnel flanges; or they can be screwed onto large diameter metal plates, which are soldered, brazed, or screwed onto large funnel flanges. Rivet nuts (AKA Rivnuts) are internally threaded hollow rivets; they come in several different types, including round splined rivet nuts, which are your best choice for attaching externally threaded gas tubes onto metal mounting plates; they are press fit in place, through deformation, like solid rivets. The main difference is that they are designed to distort easily enough that they can be trapped in place with wrenches. A rivet nut gun is not needed, for mounting a few of these rivets; they will reshape and be trapped into place, centered and perpendicular, on thin sheet metal flat washers, or on cut out sheet metal. This creates a very strong joint that is always perfectly positioned on the mounting plate; they can also be silver brazed or silver soldered into position, if you prefer. Rivet nuts come in zinc plated mild steel, which is best for silver soldering unto mild steel mounting plates; stainless steel, which is best for silver brazing unto stainless steel mounting plates; and aluminum, which forms far more easily than stainless or mild steel, easing mechanical strain on a rivet nut setting tool’s bolt; aluminum is barely strong enough for use as rivet nuts. Materials needed to make your own rivet nut setting tool: (A) One grade #8 (SAE standard) steel socket head cap screw or bolt, of the same thread size as the rivet nut, and at least long enough to accommodate every part on the tool, and still engage all the threads on the rivet nut. The reason to use a high strength cap screw or bolt, is that it is much tougher than a low carbon mild steel cap screw; extra tensile strength is needed when using a small diameter cap screw or bolt as part of your rivet nut setting tool. Mild steel screws and bolts have about one-fourth the strength of high-grade screws and bolts, which are made of medium carbon content alloy steel, that has been quenched and tempered for maximum tensile strength. (B) A minimum of two brass flat washers, to sit next to the flange screw at the head of the bolt (and provide bearing surfaces). Some people even grease these washers. More washers will simply help the bolt to turn more easily. C) Two flange nuts; one is screwed up tight against the bolt head, and a second flange nut that is drilled out or a larger size, to freely slide over the bolt’s thread (it is there to provide a bearing surface between the rivet nut and the turning bolt, with its locking surface on the side facing the rivet head (you do not want the rivet nut to turn in the hole, while being crushed into shape). (D) An open end wrench for the bolt or cap screw’s head, and a small crescent wrench for the flange nut. Drill a hole in the mounting plate that is as close to the rivet nut’s outside diameter as is feasible. A light friction fit would be ideal. The more gap there is between the rivet nut and the hole, the harder your job of riveting will become. The less gap there is between the rivet nut’s body and the hole it gets pushed into, the sooner it starts becoming trapped in place (and no longer able to turn under your tool). Screw the first flange nut tightly against the bolt head. Slide two or more flat washers onto the bolt, beside the first flange nut. Slide the drilled-out flange nut onto the bolt, with its locking side facing the rivet nut. Screw this assembly unto the rivet nut, just finger tight. Push the rivet nut into the hole in the mounting plate. Place the crescent wrench on the flange nut, and the open-end wrench on the bolt or cap screw head. Turn the bolt head until the rivet nut is securely fastened onto the mounting plate, using the wrench on the drilled-out flange nut to keep it from turning, too. You can find several videos of this process on the Net, with variations in nut and flat washer choices. Fender washers come in a limited number of center hole sizes, but it is not much work to drill or grind out a smaller hole to fit a 1/16” larger rivet nut diameter. This trick is even easier, when you need to increase a hole in a sheet metal mounting plate, a little larger than the largest bit that can be chucked in your drill motor. If you cannot find a high-grade cap screw or bolt to use as part of a homemade rivet nut setting tool, then employ aluminum rivet nuts, because 6mm rivets require equally small bolts. Even though small rivet nuts are easier to compress into shape, the problem of breakage grows as the bolt diameter shrinks. Unless they are high strength steel, ¼” and smaller mild steel bolts are likely to break off while being stressed by use as part of this hand tool. Then, malleable aluminum becomes the obvious choice for small rivet nuts. The same factors are present in commercial rivet nut setting tools, and show up as broken mandrels. Why does this happen? Because properly tempering mandrels calls for good quality control, and that is usually absent with cheap tools. For larger rivet nuts (8mm or 5/16” and up) you should choose steel rivet nuts, because, in the larger sizes, many people complain of stripping weak aluminum threads, while the rivet nut is being reshaped. Larger mandrels on the commercial tools (and larger bolts on home-built tools) are much less inclined to break. Note: High grade bolts are easier to find than imported rivet nut tools with properly hardened mandrels; these homemade tools are also inexpensive, and take up little room in a toolbox. Flange nuts: Are special nuts with a flange protruding beyond the width of the hex nut portion its bottom side, which functions as a built-in washer. Most of them also have teeth on the face of that flange, to look it in position (like a locking washer), although some have a smooth faced flange (like a flat washer), and a nylon ring inset into their hex head portion. Smoothed faced locking flange nuts are the best choice to use as the locking washer on a gas tube. You will use two flange nuts as part of your homemade rivet tool, and a third flange nut to tighten the gas tube into axially true position on the gas assembly’s mounting plate. Alternatively, two flange nuts can be used to secure the gas tube on a mounting plate without use of a rivet nut, if need be. One flange nut is silver brazed, or silver soldered to the forward-facing side of the mounting plate. The second nut is snugged up against the opposite face of the plate, to tightly trap the gas tube in an perpendicular position. 5/16”x 3/16” brass tube is 0.3125” outside diameter by 0.1875” inside diameter. 8-millimeter tubing is 0.312” outside diameter. 5-millimeter inside diameter is 0.195”. So, both 8x5mm and 5/16”x 3/16” brass tubing can be threaded for either MIG contact tips, or 3D printer nozzles. The importance of these tube sizes is, that they provide sufficient wall thickness to run exterior thread safely past the interior thread needed for a gas orifice, so that the gas tube can simply be unscrewed from a mounting plate, its gas orifice cleaned, and then replaced, without removing that mounting plate. Both 5/16-18 and M8x1 rivet nuts and flange nuts are readily available online. Thus, mounting plates can be silver brazed in place on any funnel. Your choice of funnels is greatly increased, by not requiring a built-in flange. Mig contact tips are the preferred choice for ¾” (and larger) burner sizes; with the addition of a short section of 0.020” I.D. capillary tube included, they also make the hottest ½” size burners. 3D printer nozzles are far more convenient than MIG tips with capillary tubes, for ½” and smaller burner sizes. 5/16”x 3/16” brass tube, and 8-millimeter tube, can both be internally threaded for 3D printer nozzles with an M6x1 tap; they can also be threaded for Tweco, Lincoln, Forney, and most other 200–400-amp MIG contact tips, with a 1/4-27 tap (the most common thread found in MIG contact tips). Either choice results in a streamlined gas flow between tube and orifice, permitting 2” long gas tubes to function as efficiently as 3-1/2” long 1/8” schedule #40 pipe did, previously. The tube exterior will accept 5/16-18 dies to create external thread for 5-18 rivet nuts (for use on mounting plates). However, 5/16” is only 0.0025” larger diameter than 8-millimeter, allowing it to also be externally threaded to match 8M, or 5/16-18 rivet nuts. 5/16”-3/16” and 8x5mm tubing can both be used to create gas tubes, which are screwed directly into (drilled and threaded on a drill press) ¼” thick aluminum mounting plate, and then locked in position with a flange nut. If you chose a nylon inserted locknut for this, it will stay in the correct position, without need for brazing, soldering, or gluing it on the gas tube, after the optimal distance between gas orifice and mixing tube opening is found (during tuning). Hose barb sizes for 5/16” tube: Barbed hose coupling sizes match the outer diameter of the narrowest portion of the barb; this leaves no room for threads of those same diameter. Therefore, 5/16” barbed couplings can be threaded to match up with 5/16” tube, only through their thickest section. You want to choose a hose barb that has enough length in that section to work well for threading. I suggest cutting short one leg of a straight hose barb; this should provide ½” of thread to engage the external thread on the gas tube, after sealing with thread-locker. Thread-locker comes in hardening and non-hardening types; both kinds are resistant to vibration, and the hardening type makes a stronger bond, but is not designed with the same flexibility in mind. So, be sure that the metals you bond with hardening type thread-locker are metals with similar coefficiencies of expansion; such as stainless to mild steels, or copper to brass, or to aluminum. Not, stainless or mild steel to aluminum, copper, or brass. You want all the parts to expand and contract from temperature changes at close to the same rate. Note: An aluminum mounting plate on a stainless-steel funnel, or vice versa calls for screws and nuts in slightly oversize holes, so that some part movement can be tolerated. Thread-locker for fuel lines, is rated for use with petroleum products, so you can use it to seal parts of your gas line (just remember that the hardening type of thread-locker, which makes such a convenient glue, also prevents the MIG contact tip from being unscrewed for cleaning, without first being heated up with a lighter or match).

So, just what advantages are gained in a burner from increased vorticity (which can be defined as velocity curl) First and foremost is good mixing of the fuel gas with incoming air. Propane takes a fair amount of mixing to burn completely in a primary flame envelope. A swirling motion provides the most mixing for the least drag on your burner’s air-gas mixture flow. Secondly, it speeds-up mixture flow rate through the burner, because the exit speed of air from the conical shaped air entrance, into the burner’s mixing tube, is approximately one-half of its rotational speed. Finally, vortex motion reduces the air flow’s pressure. The primary limit on flame intensity in a burner is how much it can be turned up, before being blown off the burner’s flame retention nozzle. So, lower flow pressure increases how intensely the flame can be run. Of course, a flame retention nozzle decreases mixture pressure in that area; however, the nozzle is limited in its ability to do so. A lower flow pressure into the nozzle greatly reduces the work it must accomplish.

You have it right. However, circumstances always alter cases, and we try to keep tweaking our advice to keep up with them. The latest circumstance to call along, is a flood of reasonably priced small commercial forges. What I view as first forges, because they are affordable, and small. For most of us, a larger forge isn't to far down the road, after some use with one of these beginner's models. This works out very well, because, no matter what forge people eventually think of as their ideal, that small forge will always be used whenever possible to keep the fuel bills down, and to keep the shop cooler in warm weather. But, the smaller the forge the more important those details, like floor thickness becomes; not just for cubic area, but also to keep enough room for combustion to complete before the flame impinges on the work. One of the changed circumstances, is a few vendors selling reasonably priced ceramic fiber board, to place beneath a Kastolite floor; this choice is timely, because my favorite choice of floor (a high alumina kiln shelf) has become overpriced.

So, what I'm getting at is that it's okay to watch the cartoons without your Warner Brothers hat. And by the way, just do what you need to, to reach your goal. When I wuz young and in my prime, I drunk that coffee, all the time. But now I'm old and very gray, I only slurps it once per day. The other two mugs is tea

Short answer? No; long answer is certainly not! But that is only my view. Query them about their reasons; perhaps they have good ones. Nobody knows everything. Or else we would have to call them a "know-it-all" (maybe that is a poor choice of subject for a know-it-all)...more coffee, yes, that will fix things up Okay, you are mostly dealing with hot-roding mad scientist types here; yes a bunch of them are sensible, but the rest of us try hard to ignore that, as much as we can. So, naturally our favorite answers tend to be extreme. In the real world, a made several casting furnaces from five-gallon propane cylinders, that had two-inch thick Kast-O-lite 30 linings; they work just fine, and heated up almost as quickly as the latter equipment that had 1/2" thick flame faces of Kast-O-lite 30, backed with 2" thick ceramic fiber insulation. They may take away my union card for saying so.

There are are three guys that I know of on this forum who have worked art in multiple materials. Although raised in an ornamental iron shop, I started deliberately mixing it with glass, once I rose to making design decisions; eventually, I blew glass into ornamental iron candle holders. One of the other guys on here spent years blowing glass (I think professionally). I don't know why guys on here don't talk much about it, but mixed-media was my passion, back when I was young enough to have any Frosty, I read your message, but when a paged back to the previous page, to see what guy you meant, your message disappeared. Being barely able to deal with computers at all, I have had to accept the glitches that happen on this forum

I don't have it posted, but you can buy or rent a used copy of the book Gas Burners for Forges, Furnaces, & Kilns; it has also been available for free downloads from various pirate sites for decades; and no, I have nothing against it being downloaded from such a source Yes, you definitely should use one of the burners that way. I suggest just such a course in the book.

It is good to finally see the "D." I am a fan of the oval, but despite my druthers, am forced to confess that the "D" rules

Safety limits for forced-flow burners Some part shapes used for air entrances on naturally aspirated linear burners, also work well with moving impeller blades, while others do not. However, the limits on shape and size imposed by use of moving blades, do not apply to motionless blades; these can be mounted on gas tubes without much forethought. Straight or curved wall pipe reducers, kitchen funnels, and other constricting tubular shapes, provide convenient ready-made entrances for incoming air to spiral its way through; and into the burner’s mixing tube. The air flow’s ever-smaller curve increases its rotational speed, along with forward velocity (by about one-half of the rotational speed). Also, the faster the incoming air’s rotational velocity, the lower the pressure of the incoming airflow through the mixing tube; these are all positive factors, but they require the mixing tube to be lengthened (about one-third more than with free-flow (naturally aspirated) burners) to stabilize the flame (by allowing fluid friction within the tube to slow the mixture’s swirl, before it exits into the flame retention nozzle). The first factor to keep in mind about funnels and other constrictive shapes, is the greater the ratio between the air opening’s diameter and the mixing tube’s diameter, the greater the vorticity created (the stronger the vortex). Secondly, the shorter the length of the cone shape the closer the gas jet is to the low-pressure area being created at its opening. This drop in the pressure of incoming air is not sufficient in free-flow (naturally aspirated) burners to create a problem, but the partial vacuum created at this point with the forced-flow of moving impeller blades, can draw some fuel gas back into the fan motor, if the gas orifice is close enough to it; then, the motor’s electrical sparks from brushed motors will ignite the fuel/air mixture. So, the first margin of safety in forced-flow burners is provided by sufficient length in the constrictor shape. Secondly, a maximum 3:1 ratio between the opening’s internal diameter to mixing tube’s internal diameter, helps to limit the strength of the partial vacuum created by these weak computer fans. Note: A low ratio (ex. 2:1) can be offset with a stronger fan. So, less than a 3:1 ratio in a part you are considering, need not automatically prevent you from using it. Help can also be provided by the addition of a short tube section between the funnel opening and the fan, producing the same effect as a longer funnel shape (in avoiding back-flow of fuel gas into the fan motor). Note: The moving fan blades you are concerned with here are impeller blades, which have become standard on axial computer fans; not the old-style flatter blades, which are meant to push air forward; those increase the pressure of incoming air. Impeller blades lower the pressure of incoming air. Be sure to seal the joint between the fan and and the funnel opening, to prevent air from being flung by the fan blades, through any gap; this will suck fuel gas through that gap, along with the air, and then into the fan entrance. Choose a brushless motor, if you can. Brushed motors constantly create electrical sparks between their two brushes and the commutator; they will ignite any fuel gas that enters the fan entrance. Brushless motors are very unlikely to create sparks. No sparks mean no ignition of stray fuel gas. The chance for sparking in a brushless motor is not zero, but it is close; good enough as one safety choice, among others. This leaves us wondering how much funnel length is long enough with impeller blades. Only experience can answer that question. Furthermore, fan strength, constrictor shape (straight, convex, or concave wall) all come into play. Add to that, how much curvature, at what point in a funnel shape, and we are reduced to trial and error. Always remember that, if the burner you design starts backfiring into its fan, there is very little work needed to change it over to a naturally aspirated design. You do not have to rebuild the whole burner; just stop the fan.