Mikey98118

To skip to the bottom line, a Diamondback single burner propane forge is the only commercial forge worth owning in your price range. I believe you will find it perfect for your needs. You will find this forge gets hot enough, and more to the point, it is made to last. Could you do better? Yes, but only by spending a lot of time learning how to build your own burner and forge. I don't think you want to spend that kind of time on a peripheral tool, right? And if you change your mind later on about how deeply you want to delve into metal work, the Diamondback forge can be easily upgraded, with the latest burner design. I would have suggested a Mister Volcano forge, as giving by far the most bang for the buck, but you are not likely to find one for sale, anymore. By the way, all the photos you posted, both of burners and of a forge shell, are second rate choices, which will utterly disappoint; just don't go there.

I like Jay's construction choice for how to mount his burner's gas tube; it is clever. However, I disagree with his reason for it. Aiming the gas orifice at a slight angle will promote mixing of fuel gas and inducted air within the mixing tube, just as his drawing shows; but at a cost to the mixture's flow speed down that tube. Where as, increasing the bell reducer's opening diameter enough to get a three to one constriction ratio will accomplish all necessary mixing of fuel gas and air, without sacrificing mixture flow speed. The faster the mixture can exit the burner's mixing tube, into the flame retention nozzle's area, the more intense the flame that can be produced. You can create the same effect that Jay used by holding a gas tube and orifice at the rear of a burner's mixing tube, without the bell reducer on it, and moving it around to see how it affects burner performance; that little experiment is very enlightening, and will show both the good points, and severe limitations encountered.

Run-out (AKA runout): Any rotating tool is meant to revolve on its center. If its spindle isn’t machined true (centered and parallel to its axis), accessories mounted in a rotary tool, or die grinder will orbit in a tiny circle around its axis, instead of revolving on it, producing heavy vibration; this is called run-out. In fact, it is inevitable that all rotating tools will have some run-out; just not a noticeable amount. If a micro drill’s keyed chuck is not mounted true on the motor’s spindle (usually because the tiny brass arbor that connects them is not machined true, or carefully mounted), the micro drill bits mounted in the tool will also orbit around a tiny circle, and quickly break. Any drill bit, or stone mounted in the tool will have the same problems as they do in rotary tools and die grinders with run-out, but to a lesser extent, because of the drill’s lower speed range. The larger an abrasive stone’s diameter the easier it is to break; especially in a tool with run-out. If you cannot deal with that, there are tungsten carbide burrs that won’t break anywhere near as easily; of course, a tool that is heavily vibrating from a run-out problem will tend to fling them about. But at least this will adequately demonstrate that the stones were never your problem. Diamond coated chainsaw burrs, don’t break apart; nor are they as inclined to be flung about, as tungsten carbide burrs. But, run-out will quickly dull the diamonds, and even knock patches of the diamond coating off. Properly securing and balancing rotary accessories: Fully insert accessories into the tool’s spindle, and just snug the collet nut; do not over tighten, or you might strip its threads, or even worse, the spindle threads. There is a good reason why collet wrenches are so tiny. Take the hint. I have yet to buy an accessories kit that does not include a little rectangular silicon carbide dressing stone; they are used to help balance the softer aluminum oxide grinding stones, wheels, and cut-off discs. Employ that dressing stone to counter-balance accessories; keeping your rotary tool from suffering degradation from excessive vibration. Cheap rotary tools are likely to have spindles, which were machined significantly out of true with the tool’s axis; if you add unbalanced accessories to that, bent shanks and thrown accessories are the next trouble that will be flung your way. A few light touches, with a dressing stone, can save you a lot of grief. You can also buy inexpensive, larger, dressing stones, when it wears out. Rotate accessories that can’t be balanced with a dressing stone (like steel discs, brushes, and sanding drums) a quarter turn at a time (in the spindle), to improve balance.

That is to say, metric threading on any external thread. But, what if all you can find is 8mm by 2mm thick wall brass tube? The only thing that changes is that you will need to enlarge one end of the tube with the recommended drill bit for the size tap you will be using to create internal thread for the MIG contact tip.

This presumes that you already know the total width recommended for those air openings. You will find that the three ribs left between the air openings will end up a little wider, and therefore stronger.

Silica content in refractory and ceramic products serves as one form of binder, among others, and also, depending on amount, as waterproofing. Clay, which are the most common refractory and ceramic ingrediant, runs around sixty percent silica content. High alumina refactories run between forty and five percent silica. However, fumed silica is also used as a binder in some refractory products; probably becuase of their low melting temperatures, in this form.

What you are trying to describe is a brick pile forge; these have become quite popular, since the new series of insulating firebricks came out, making them practical, affordable, and easy to build. Frosty has posted photos of his group's little brick pile forge here on IFI. This particular photo is worth a thousand words One of the many advantages of this design is that the problem of cracking in internal hard ceramic corners do not apply. Uneven heating of corners in forge design also no longer matters, with better building materials and much hotter burners. Finally, be sure to mount your two little burners high up on a side wall of the forge; not on the top, so that their flames are aimed at the far wall, and well below ceiling height. There are also photos available showing how to do that, sans any welding. Do you want to take it from here, Frosty?

The most important change was the gas tube. You want the gas tube to have an inside diameter close to 3/16" or 5 millimeters. When the tube is threaded for most MIG contact tips, this will provide a smooth transition of pressurized gas from the tube into the MIG tip. This improvement may cover for less than perfect work elsewhere in your burner's construction. The simplest choice for Americans, is to special order schedule #80 (rather than the standard schedule #40) 1/8" steel water pipe, for your gas tube, because pipe thread will easily match up with needle valve or pressure regulator fittings. 5/16" x 3/16" brass or aluminum tubing is the next choice, although it calls for threading the tube yourself, silver brazing, or silver soldering the tube in place. 8mm by 5mm tubing will also work just fine, but calls for metric threading. The other change is three equally spaced air openings; no more and no less; this provides the maximum air induction, and spin, with the maximum rib strength.

The why of burner sizes Why do we discuss such a wide range of burner sizes, here? Size is relevant to use. What is large as a hand torch, or in a mini-forge will be too small in ceramic kilns, or commercial forges (which use one or more 1” burners). 1” burners provide four times the heat output of a ½” burner. Flame control is about more than choosing the right burner design, and proper tuning; it is equally about selecting the proper burner size. These are primarily used as equipment burners. So, understand that heat management only begins with increased heat output. The reason burners are aimed on a tangent, is to cause their combustion gasses to swirl around equipment interiors, creating a longer distance from flame tip and exhaust opening. Obviously, a lengthened exhaust path increases the amount of hang time, for hot gases to deposit combustion energy on internal surfaces. What is not so clear is that the heat gained is not added by these gases blowing an extra foot or two at high speed; it is due to their continuing drop in velocity over every added inch of distance. Hot gases begin to slow, as soon as they leave the flame envelope. The flames of two 1/2" burners will use the same amount of fuel to produce an equal amount of heat as a single 3/4” burner; but they will drop velocity much faster in a five-gallon forge or casting furnace, increasing efficiency, because their flames can burn faster/hotter without creating a wasteful tongue of fire out of the equipment’s exhaust opening. Ditto for two 3/8” burners versus a single ½” burner in a two-gallon combination forge/furnace, or two ¼” versus a single 3/8” burner in a one/gallon forge/furnace. When forging small parts, further efficiency can be gained by placing a temporary partition in equipment interiors; separating them into twin spaces, and shutting down the rear burner. This is something that cannot be done with a single larger burner, which is centrally located. Combination forge/furnaces can have the forward burner shut down during casting operations, so that its flame is not wasted, from being positioned too high up the crucible. If a little is good, than more most be better, right? Usually, that is wrong. The exception is multi-flame burner heads, such as ribbon burners; these burner heads allow multiple tiny flames to take the most advantage of flame speed slowing. However, this technology is not perfected. I believe it is far enough along, that home-built ribbon burners are a practical choice for some beginners. But, they are not for me. Not that multi-flame burner heads aren't a cool idea; its just that I'm a perfectionist. Until someone comes up with a perfect flame from ribbon burners, I just ain't interested. That shouldn't stop all you practical people out there

That is about all they are good for

What I would like to see, would be these people going up market a little more, and competing in the $400 to $700 forge range. There is nothing stopping them from blowing their outdated competition away, and the prize would then be worth their continuing effort

The tubing most burners are built from, cost less, as their sizes decrease. When buying from online sources, it is usual to find two or three small tubes offered for little more than a single tube, because the sellers want to justify a minimum price, on every sale, and two or three additional small tubes, cost them nothing extra to ship. The MIG contact tips, or 3D printer nozzles used as gas orifices, are also sold in small amounts, rather than as single items. Ditto for 1/8" gas pipes. So, multiple smaller burners cost little more than larger single burners to build, but they do call for added work. only the price of an additional conical shaped air entrance is added onto smaller linear burners. However, prices will decrease less for burners made of pipe parts, because the manufacturers of those parts have more invested in them. You are paying a higher price, to get more of the work done for you; a good trade off, just so long as they will align properly, after assembly. Screw your parts together, and look them over carefully, before purchase.

there are as many designs for openings as there are people to dream them up. I say, the more the merrier. However, what is important, is that a gap between the the sliding door(s), bricks, or whatever, is maintained between it and the forge opening. It is through this gap that the exhausted gases flow up and out, so that no back pressure builds up in the forge, no matter how small the opening is around heating parts. Theoretically, the perfect baffle wall, would be a solid barrier, with an opening of the same shape as heating stock, and only a little larger than its size, to slide the stock back and forth through. As usual the perfect is the enemy of the practical. I am only bringing up this example, to illustrate a point. Obviously, in this extreme example, there is no room provided to git rid of hot exhaust gasses, so they must pass out between the baffle wall and the forge opening. The point is not to try to emulate the example, but to keep the goal in mind. Everyone ends up doing what works best for them. The point is to keep in mind why what goes where

Agreed. However, what terms will or won't stick, usually boils down to what the readers like

I would call the "accelerator block" a conical air entrance," once, and then just "entrance" afterward.

What a neutral flame is, and is not Does a neutral flame create more scale on heating parts than a reducing flame? NO! The problem is that most guys don't see the difference between a neutral and mildly oxidizing flame. Also, many propane systems pulse; they do not feed a perfectly steady gas supply, and so the burners they serve, can end up running with a neutral flame part of the time, with an oxidizing flame, the rest of the time. This is a minor problem, unless the burner is tuned to put out a slightly oxidizing flame, to begin with. Unfortunately, this is often the case. If you tune your burner to a slightly reducing flame (just a feather of secondary flame showing beyond the primary flame envelope), once you get rid of the secondary flame completely, you will have a neutral flame. You can tune the burner quite a bit leaner, before the flame starts to darken, showing that it is an oxidizing flame. However, that considerable range of flame leaning, before it begins to darken is NOT neutral!!! Your flame became oxidizing the minute you started leaning it further. At the point where the secondary flame envelope disappears, you have a neutral flame; anything beyond that is oxidizing; it is not a short range, from neutral to oxidizing; it is a single point. So, the safe bet, is to leave that bit of secondary flame showing. But, doesn't that sacrifice forge heat? Yes; the hottest flame is a neutral flame. Both slightly oxidizing, and slightly reducing are colder than neutral flames. However, the slightly reducing flame is hotter than the slightly oxidizing flame.

Improved linear burners Linear burners, with conical air entrances are the best design for creating vorticity. So, just what advantages are gained in a burner from vorticity? Primarily, increased mixing of incoming air with the fuel gas jet. 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 increases flow speed 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, a vortex reduces the incoming air flow’s pressure. The primary limit on flame intensity in a burner is how much it can be increased, 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 reduces the work it must accomplish; enabling harder flames to be retained. When incoming air passes through a conical shape, such as a pipe reducer or kitchen funnel, vortex movement (vorticity) is generated. Most successful burners, whether linear or jet-ejector, create some vorticity. High-speed tube burners are an exception; they gain air spin from three (fore and aft beveled) rectangular side air entrances; nevertheless, if you place a cone section between those air entrances, and a smaller diameter mixing tube, their performance can be enhanced; in fact, you must be careful not to create too much of a good thing (burner design is a balancing act). Since most successful burner designs create vorticity, why bring it up? Because the people who designed those burners, only pictured them as swirling incoming air into a stream of fuel gas, and thought no further. Any device that provides lateral air movement at the burner’s air opening, will boost vorticity through its conical shape; this includes the two openings on “T” plumbing fixtures (whose opposed inlets create swirl at the opening of the smaller central outlet (the conical restriction created within this outlet, then increases that swirl); disc shaped choke plates near funnel entrances (which force incoming air to change direction at the air entrance (starting a swirling motion at the lip); or impeller blades placed at a funnel’s entrance (which deflect the direction of incoming air laterally, starting swirl at that point). All this redirection of air trajectory is minor, but it creates the right vector at the starting point of air movement. It takes no more energy to induce air laterally, than to induce it straight into the burner’s air opening; less energy is then needed to redirect speeding air molecules within the conical shape; thus, providing a boost to rotation. If you remove the blades from a cheap or worn-out axial computer fan, and mount them on a linear gas tube at the burner’s air opening, they will significantly increase vorticity through the funnel, even though they are still, because they start lateral air movement (swirl) at the funnel’s entrance, instead of further within it. The fan blades do not need to be the same diameter as the funnel. Plastic blades of larger diameter are easily cut shorter, with scissors.

To make this clear, your burner's design does not have a sufficiently large diameter in their openings to provide sufficient swirl in the incoming air; the ratio of intake diameter to mixing tube diameter should be a minimum of 2.5 to 1, and is best with a ratio of 3 to 1. There are two aspects of the burner which provides an acceptable flame. The end plate (choke) will, at just the right distance from the opening, provide added swirl. The second help is the ring of holes in the burner's flame retention nozzle. Neither nifty little gimmick is quite sufficient by itself; they are just enough, to do the trick, working together. However, while your burners have adequate flames, they are not strong flames; that will impact what you can do with the burners. My advice would be to remove the ceramic wool from the burner portals, and add sheet metal "washers" on your burner's mixing tubes, which can be moved back and forth on them, and held in place at the best distance from the portal openings, to limit--not stop--secondary air, which the burner flames induce into the forge. As to the yellow streak in one burner's flame, and the red streak in the other burner's flame; I strongly suspect that they are cuased be oxidation of the stainless steel nozzles. I am pretty sure that there is nothing to be done about the streaks; on the other hand, they are not secondary or tertiary flames. In other words, they should be ignored. What does this leave to see in the flames? I see complete combustion going on in single flame envelopes; that is as good as you're going to do. "If it ain't broke, don't fix it." So, tweak the forge; not the burners.

No, it would not be improved, if you remove that "end plate." All that would be true then, would be that it is a weak burner.

I am familiar with the burner configuration, and this design usually makes a weak flame. Your burners are an exception to the rule, and I suspect that it is entirely do to their unusual flame retention nozzles.

I have always placed great trust in people...to act out exactly who they are; be that good, bad, or simply lame.

Please stop those quotes from the 70 Maxims; I looked them up, and ashamed to say that I luaghed so much. No, seriously; I am really ashamed. You believe me about that, right? Ya just know I wouldn't lie about that, right?

Big toothy grin D. John

Please put the gun down; we can work this out peaceable

Was that unkind? No; if I wanted to be mean I could have mentioned their joke of a burner