Mikey98118

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.

Thomas has answered the question wondrous well on this thread; unfortunately, his very well thought-out remarks can only serve as a summary, because the subject starts simply in theory, and turns complicated in practice I would suggest putting it in your shop notes and rereading it a couple hundred times (as an introduction).

Oh, that was a good one, Frosty; you just know I'll borrow the heck out of that!

I think the reputation of being weak on heat has come from the various people who have tried them to heat home casting furnaces; the problem is that their rather perfect flames have been coming out of brass flame nozzles, which must be kept at a small distance from the equipment openings, to keep such nozzles from melting. When a flame enters that way it induces massive amounts of unneeded secondary air; I believe this is where the underwhelming view of their heating potential springs from. Anyone can see videos of some of the refurbished old-fashioned models running on the web; one look at their flames, and you now weak flames ain't their problem. The new burners have steel flame nozzles; end of problem. That should read "know"...

Liquid fuel burners Kerosene, and then gasoline burners have been around for over a century, and both the original pump-up hand burners and the new oxy-gasoline torches are available today. The classic kerosene and gasoline hand torch makes a single flame envelope of neutral blue, which is nevertheless rated by so-called experts as burning at a lower temperature than propane; I do not believe their conclusions. What made the old style gasoline burners dangerous were their leather seals. There are modern versions of such burners available from China, which use modern plastic seals, and steel flame nozzles, instead of brass, which can serve well enough in forges and casting furnaces, in places were gaseous fuels are scarce or expensive. There are also safer English manufactured gasoline weed burners, which have a separate gas tank and flame head, for the cautious-minded.

Actually kerosene, and then gasoline burners have been around for over a century, and both the original hand burners and the new oxy-gasoline torches are available today. The classic pump-up gasoline hand torch makes a single flame envelope of neutral blue, which is nevertheless rated by so-called experts as burning at a lower temperature than propane; I do not believe their conclusions. What made the old style gasoline burners dangerous were their leather seals. I don't think Andrew's burner design is anywhere near that dangerous.

Regulators at a glance Many torch regulators can be used with LPG--but never old acetylene regulators; some new acetylene regulators have seals that won't be dissolved by LPG fuels. Unless you have a gas equipment EXPERT telling you that a newer acetylene regulator has the right kind of seals, don't use it; gas equipment fires are not fun.There are more multi-fuel shop regulators becoming available on torch sets; they are safe with LPG. The most useful regulator is a 0-30 PSI (pounds per square inch.) LPG (liquid petroleum gas) regulator. The cheaper 0-20 types are good enough for forge use if you're careful with them, but don't kid yourself that all you lose for half the money is some pressure range. the 0-30 regulators are much better quality IF you buy the main brands; there are lots of cheap import look alights being passed off on the careless! Careful use starts with always closing off the pressure on your regulator when you shut down the forge. Open the regulator slowly when you start up the forge; you don't want full cylinder pressure slamming against your regulator and pressure gauge parts. BTW, look-alike equipment is also flooding the market on torch regulators too; if you don't see a well-known brand name on the equipment, it is probably junk. NOTHING prevents you from using any LPG regulator. It doesn't matter about matching up threaded fittings from different countries. Regulators can all be put together with any pipe fitting, using a short length of fuel hose, and barbed hose fittings. There is no free lunch. If you think a proper regulator is too big an item in your forge budget, make cheap with something else; not the regulator. Just about everything in your forge and its burner can be upgraded later, but regulators are only going to go up in price.

Many torch regulators can be used with LPG fuels, but the most useful one is a 0-30 PSI LPG regulator (the cheaper 0-20 types are good enough for forge use). Some shop regulators can be used--but never old acetylene regulators; some new acetylene regulators have seals that won't be dissolved by LPG fuels. Unless you have a gas equipment EXPERT telling you that a newer acetylene regulator has the right kind of seals, don't use them; gas equipment fires are not fun. NOTHING prevents you from using any LPG regulator you like. It doesn't matter about matching up threaded fittings. Regulators can all be put together with any pipe fitting you like, using a short length of fuel hose, and barbed hose fittings.

And it is still on the street for looks of reasons; not least of which is how easily it can be upgraded when its user wants more from his forge.

Well, before going to all the trouble to add more burners, I would change out the reducer fitting on this one. Reil started out recommending a 1-1/2" X 3/4" reducer on his original burner design, which I upped to a 2" X 3/4" reducer if you replace the drilled side hole in the gas pipe with a MIG tip

Yes, you certainly can use a drilled orifice (try .026" ot .028" diameter) ; I would suggest starting at 3/4" long for the gas orifice, and shortening by 1/16" or less at a time, until you are satisfied with the flame, using a 1/8" diameter hole on the rest of the length that a MIG tip would take up, if you were using capillary tube in a copper MIG tip, instead of deep drilling into half hard brass round bar. Understand that you flame is so close to right that it won't take big changes to go the rest of the way.

We will get to that, but first I gotta say you did a slick job on your forge shell and table; I love to see smart metalwork work. As to the burner; it's not easy to be sure about its construction in a flame picture. However, the flame itself tells me that you are very close. One of the things that causes a lot of confusion is proper size of MIG contact tips; they don't just change in accordance with burner tube diameters; they also change to some degree by mixture flow. Frosty runs a little bit large MIG tips in his burners then I do in mine. A 3/4" Mikey burner is meant to run with a MIG tip for .030" wire as a maximum and a tip for .023 welding wire as a minimum. So before we go any further, try checking out your tip options to see if you can make the magic flame the easy way

Why do I feel that this thread will soon be closed?

So, with a three-burner forge cooling from the excessive secondary air, can combine with high back pressure from too many burners, too make the third burner of little worth for the fuel wasted.

Your burner works well enough to use as is; that doesn't mean there isn't room for improvement.

3.5% is what the author of the original article suggested for making refractory tiles, etc. He suggested 5% for making finish coating. what other guys making these products use is a different matter.

Your forge temperatures look good. But that very large exit flame is so reducing, that it is blue; not good. I hope you have plenty of cross breeze going in your shop. Just becuase the forge is done, that doesn't stop you from pulling the burner out and improving it in your spare time...