Mikey98118

Flames with added oxygen, full or partial, can be laminar or turbulent, and still be very hot. But air-fuel burners are nearly all either turbulent or weak. I have only seen one burner with a very hot laminar flame, and that was a "T" with a flame nozzle.

More on flame stability Hard flames, (AKA High-speed) have a greater tendency than softer flames to become unstable; how much stability is needed is an individual choice. I have not found a problem in most people in judge wisely on this issue. However, one thing that is true with most burners is that burners small than 1/2" are easiest to tune for hard flames and easier to tune into instability. Fortunately, unstable flames become more stable on burner installed in equipment.

I like to show new forges with something outstanding about them, so here is my latest find; an outstandingly bad deal: https://www.amazon.com/Handy-Forge/dp/B018WLH9JS/ref=sr_1_2?ie=UTF8&qid=1514574700&sr=8-2&keywords=black+smith+forge Why bring it up? For that much money, newbies could actually buy a real beginner's gas forge from eBay. To add insult to injury you have to buy a torch to run it with, because it is sold without any burner; it is so small that it makes a coffee-can forge look huge; it is made with highly friable insulating firebrick, so you don't have to wait for heat damage to start turning the "firebrick" into rubble, because shipping will start the job for you.

well, put, Buzzkill.

Yes yr it sure will.

I use actual inside diameter times nine, starting from where the flare of the air inlet or forward ends of side air opening's forward end or ends stop and the mixing tube area begins. The nine diameters rule of thumb should be regarded as a general reference point for burners, as it is changeable not only according to mixture flow dynamics, in accordance to burner design, but also by preferred desired flame dynamics. I have chosen as much as ten diameters in burners meant primarily for hand torches and as few as eight diameters in burners meant to output the shortest flames possible in a stable Mikey burner, while eight diameters are Frosty's recommendation for his "T" burners.

I have seen these burners before, and believe they will burn hot enough, but...the flame nozzle materials are so thin as to be considered very consumable. Some people won't be bothered by this, and others will.

Yes, a regular .6 millimeter contact tip will work but is just a hair large to work at the maximum advantage in a 1/2" pipe burner.

Please be careful with that cutting sarcasm; I'm weak and old. Making me laugh that hard very often is likely to finish up the job

Okay, here's my first suggestion.; look up a schedule #40 pipe chart, to see what nominal inside diameter a 1/2" pipe has and add an additional 1/8" diameter to it. Then use tubing, which comes in a whole lot more sizes than pipe, to get the desired diameter or as close to it as is convenient; this is a lot easier than using capillary tube to match up the MIG tip better to 1/2" pipe.

You can simply look at the "T" burner threads and build a perfectly adequate burner from that. I do not recommend going through Burners 101 as a first step in deciding how to heat a forge. Build a simple little forge first, and take your time going through that rather large thread at your leisure. One of the sad misconceptions about burners is that you won't make several; you will.

SLAG, Burners 101 is a permanent thread.

Thank you for your post. I'm reasonably sure questions will come up about particulars, such as hammer patterns during the shaping of these cones. I like the flanges, which should be handy for running electrical wiring and gas tubes down. So what size and kind of linear burner (atmospheric or Vortex) do you wish to build? Remember that Vortex burners can be run in atmospheric mode, or with the supercharger on; either way, it gives an enhaced performance, but with the impeller blades running it can be run a lot harder.

Post a how-to on this subject here, sharing your knowledge with others, and I will go out of my way to help you all the way through your burner builds, step by step and till they are done.

If you know enough about the equipment you can do just fine with either kind of forge; if you don't, then what you build probably will be a mess, whichever kind you choose. It's hard to reach the right conclusion when starting out with the wrong question.

Forges 101 and burners 101 make a good grounding, but don't overlook the "T" burner and ribbon burner threads.

G-son states "The basic plan is a linear burner, because I have read here they work well in small sizes. I'd like to use a MIG tip for simplicity (assuming the gas canister can give off gas fast enough to feed that, worst case I'll have to put it in a water bath to maintain temperature), if I can get my hands on a more suitable jet in the 0.5-0.6mm range for a good price I'll might go with that instead. Either way, I'm aiming for somewhere around 3/8"-1/2" mixing tube. Mixing tube length rule of thumb says 9 times diameter, although I remember someone mentioning handheld small torches might benefit from longer tubes. I'm thinking 10-11 times diameter to begin with, shortening it is simple. Sorry for the slow reply; it is the flu season in my house. The smaller a burner is below 1/2" size the trickier it is to tune. The smallest Mikey burners I have built are 1/4" size; while I can make them run with perfect flames, they have a very short turn-down range, which means that I can build hotter linear burner because their lower quality flames can be turned up much stronger. Smart is as smart does. I'm thinking a stepped nozzle. Overhang slightly longer than mix tube ID. Not sure about nozzle ID, but that should be simple to experiment with. I went through a phase were flame nozzles were kept as short as practical; this is a mistake with smaller burners, because axial alignment becomes much more important in every part of them. 2-1/2 times the mixing tube diameters work out best. About 3/32" to 1/8" thick spacer rings in step nozzles generally work out best. For the other end of the burner, I'd like some input. If I understand correctly, linear burners likes to have some sort of "funnel" before the mixing tube, with a starting diameter of ~4x tube ID. No; a three to one ratio of air opening to mixing tube inside diameter is what I recommend for Vortex burners, and the minimum ratio I would recommend on for linear burners without superchargers. I can easily cut and roll a cone of sheet metal, and weld or braze it to the tube, would that be a sensible construction? Aerodynamically, it would seem way better than the pipe reducers others have used successfully... although sometimes you need a "less aerodynamic" design to cause some turbulence or for other reasons, so that might not be a good thing. Also, if such a cone seems like a good design, should I go with a short cone with steep walls (red in the picture), or a shallower, longer cone (green)? I'm guessing the shallower cone would flow more air (perhaps a good thing with a 1/2" tube and slightly too big MIG jet), but again, aerodynamic efficiency isn't always what you need. I'm guessing I'd want some form of air choke. Right now I don't have a clear design for the gas jet/tubing or how it will be held in place, that depends on what I can get my hands on, but something like a washer sliding on the gas pipe should work for choking I think? (Orange on the picture.) If you can easily create your own sheet metal cones, then you have a great advantage, because you can choose to use longer cones; here is a fine place to go with four to one length to diameter.

True; a neutral oxyacetylene flame will leave some additional carbon in a weld bead; this is why the process used to be used for ribbed spring steel engine tubing.

Well, if it is in print it must be true--not.

I believe that that carbon monoxide has no ill effects on heating steel; the same can't be said about your lungs.

So this is what happened to you. Are you going to build ribbon burners next?

I have been of divided mind about them for years. The new ones could be very nice for folks in the third world. However, I'm in the highly litigious first world....

It's true that professionals who knew what they were doing, safely handled these torches when they were new. However, I believe their present reputation stems from ignorant newbies trying to refurbish ancient piles of junk into serviceable tools, sans experience. There are videos on the web showing perfect flames coming from some of them, besides others that are barely running. I find this to be the same kind of challenge newbies with any other kind of burner face.

Insulation It only takes a moment's comparison between heat lost through an exhaust opening with heat lost through forge walls to make it clear that just insulating the forge, to lower heat loss is a waste of time. You are insulating the forge to superheat its internal surfaces into high levels of incandescence; at least into yellow, and hopefully into white-hot ranges. An efficient forge is a radiant oven. The burner flame is primarily used to create radiant heat transfer; not for heating stock directly; get that straight in your mind, or give up all hope of knowing what you're doing in forge design. Why? Because every choice you make about refractories, kiln shelves, and ceramic fiber products needs to reflect the need to superheat the forge interior without gutting those materials. Insulation in walls and under the floor have consisted of two one-inch thick layers of ceramic fiber blanket for many years inside curved forge walls, and one-inch layers of ceramic board, with a further one-inch layer of ceramic blanket between the board and forge shell, in box forges. K26 insulating firebricks have become a tougher alternative to a ceramic board in box forges and a better alternative to ceramic blanket under floors in round forges; they are available from eBay and other online sources. There are several kinds of refractories used for hard firebricks, but only one kind that used to be sold for insulating firebricks, until recently: that was the pinkish to yellowish bricks made by including a foaming agent in clay refractory to make the lightweight bricks that are use rated to 2300 F, which you see used all too often in old gas forges, and electric pottery kilns. To call them friable is to completely understate their fragile nature; calling them future rubble is more to the point. Such bricks are better used as secondary insulation in things like Pizza ovens; equipment that tends to heat up and cool down slowly during very long thermal cycling; just the opposite of a forge.

Brazing hearts have fascinated me for several years; I'm not done with them yet.