Burners 101

[Mikey98118]

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?

[Frosty]

Anything you say Mike, you betcha!

A little trust goes a long way. The less you use the further you'll go. #30 from, "70 Maxims For Maximally Effective Mercenaries." 

Read the whole web comic, "Schlock Mercenary." Thomas Powers clued me to this and "Doc's Whiteboard." Schlock is no longer being written. <sigh> Doc, of the Whiteboard lives in Ninilchik about 300 miles from here and is a major player in building, repairing, selling, paintball equipment. 

Frosty The Lucky.

 

[Mikey98118]

33 minutes ago, Frosty said:

A little trust goes a long way. The less you use the further you'll go.

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

[Frosty]

I'm not very warlike nor mercenary myself. I give people the benefit of the doubt pretty reflexively. I make decisions after I've known them a while though it doesn't take long to get some people's number. People are who they are and few can hide it very long. 

Reading what others write makes it very easy for me to get a "read" on them. Usually about 200 words, some longer others in the first paragraph. 

I'm not as good at it as I used to be, catching a tree with my head didn't help.

Frosty The Lucky.

 

[George N. M.]

Jerry, I've been reading "The Whiteboard" for about 15 years now.  I just discovered "Schlock Mercenary" and have been binge reading it for the last 2 weeks.  I'm up to about mid-2006.

[Frosty]

I've binged "Schlock Mercenary" to June 2012. It gets stranger and funnier. I believe I have another 10 years to binge through. 

I check the Whiteboard before looking at email or the forum daily. 

Jer

[Mikey98118]

On 9/20/2024 at 7:28 PM, Mikey98118 said:

On 9/20/2024 at 7:28 PM, Mikey98118 said:

 

                                                                     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.

[Mikey98118]

                                                                     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.

 

[Mikey98118]

    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.

[Jake18]

I am about to begin building a couple of Mikey Burners. I’ve read through the forum several times a while back but haven’t had time to make a burner or go back through the forum due to college. I vaguely remember you talking about some modifications to the burner design in your book and I was wondering if you could give a summary of the modifications you would do to the original design.

[Mikey98118]

1 hour ago, Jake18 said:

I am about to begin building a couple of Mikey Burners. I’ve read through the forum several times a while back but haven’t had time to make a burner or go back through the forum due to college. I vaguely remember you talking about some modifications to the burner design in your book and I was wondering if you could give a summary of the modifications you would do to the original design.

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.

 

[Mikey98118]

On 10/12/2024 at 7:51 PM, Mikey98118 said:

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

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.

[Mikey98118]

On 10/12/2024 at 7:51 PM, Mikey98118 said:

8mm by 5mm tubing will also work just fine, but calls for metric threading.

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.

[Mikey98118]

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.

 

 

[Mikey98118]

                                                       Air entrances on linear burners

So, just what advantage is gained in a burner from from a conical shaped air entrance, such as a pipe reducer fitting, on a linear burner? Mainly, increased mixing of incoming air with the fuel gas. 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.

    Any device that provides lateral air movement at the burner’s air opening, will boost swirl through its conical shape; this includes the 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 fan 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.

 

So, we see how disc shaped air chokes on the entrances of modified pipe reducer fittings got their start; they do help create swirl, but why would they be needed? Because those air entrances, which were especially cast for this purpose,used existing pipe reducers as their models. Unfortunately reducer fittings for water pipe tend to have two to one or smaller constriction ratios. Anything less than a two and one half to one ratio is insufficient; three to one constriction ratios are better. This is why I avoid threaded pipe reducers for linear burner air entrances.

[Mikey98118]

                                             The burner's mixing tube; your second chance

So, if you want to use a threaded pipe reducer, are you kinda out of luck? Nope, you can still get up to a 2.5 to 1 constriction ratio; it just takes an added step or two. The best news is that, if you already purchased a badly designed burner, it can be improved, in just a step or two

  If you internally bevel a short length of schedule #40 pipe (standard water pipe from the hardware store), and screw it into the reducer fitting, that reduces its internal diameter about 1/4". If you use  schedule #80 pipe, the reduction is about 1/2". Be sure to bevel that pipe end, so that the internal conical shape is not interrupted!

  Now drill and thread one or more screw holes through both  the pipe fitting and the spacer you have just screwed into it, so that the mixing tube, which is also to be internally beveled, will be held firmly in place, after being pushed into this collar. If you use the next size smaller pipe, it will need to be power sanded a few thousangths, to fit into this area.

  But, how long should the mixing tube be? Too short, and the gas will not completely  mix of with incoming air. Too long, and it slows down the mixture's flow speed into the flame retention nozzle, weakening performance. Although it will very, depending on burner design, between eight and nine times the tube's internal diameter, generally works out quite well on naturally aspirated burners. So, start at nine diameters, and cut back a 1/4" at a time, to reach optimal performance.

  But, what about existing burners? Cut off the mixing tube, even with the end of the pipe reducer. Next, cut the off the flame retention nozzle, even with the mixing tube. Drill and thread one or more holes in the flame retention nozzle, and in the pipe reducer, to slide the next smaller mixing tube into; remember to cut the new mixing tube at nine times it internal diameter, to begin with.

  Won't you need a smaller gas orifice for a smaller mixing tube? Perhaps, but my experience has been that nearly all those cheap burners had oversize gas orifices, anyway. If, not, push a short piece of syringe needle into the existing gas orifice, to make it smaller.

If the the part used for the burner's gas orifice permits, its hole can be enlarged and threaded for a 3D printer nozzle, if you do not care to fool around with needles, are capillary tubing.

[Mikey98118]

                                                                                   Flame retention nozzles

The first question to ask, is do you need one, if your burner is placed within a forge; probably not. Do you want one? Definitely. Because your forge will most likely run just fine without a flame retention nozzle mounted on its burner, why bother? Well, some people don't bother with one. However, if you have no flame retention nozzle on your burner, I hope you at least screwed a pipe coupling over the end of your burner's mixing tube; otherwise the mixing tube itself will start oxidizing away, within the forge.

  The point of all this is that you have plenty of time to provide the burner with a flame retention nozzle.

  I see lots of pipe reducers being employed as nozzles; if your reducer ends up a little too large, a short piece of stainless steel pipe or tube can be held within it, with a stainless steel socket set screw. Be sure that the screw is stainless. Mild steel will become stuck in place, after a few heats.

  Moving the short piece of pipe or tube forward or back within the reducer will change its width to length ratio, just as effectively as moving the position of the outer tube does with a slide-over step nozzle; allowing you to fine tune burner performances, in the same way. Once again, this improvement does not have to be done right away.

 

 

 

 

[Mikey98118]

                                                                    Drilling in steel with a rotary tool

This takes more delicate work than a hand drill requires. The chucks on rotary tools have a maximum of 1/8” capacity. Furthermore, these tools spin far too fast for even a 1/8” drill bit to last very long, when drilling in steel. By turning their speed down to the bottom of the tool’s range, a 1/16” M35 drill bit will work to create pilot a few holes in tubing or pipe, which can be increased to 1/8” with a tungsten carbide rotary file, and then finished with a diamond coated rotary file (both of these rotary tool accessories are sold in kits for as little as $10).
 

    Hand drilling holes with rotary tools for 8-32 thread taps (which are used on small flame retention nozzle holes for socket set screws) can be done if you are careful; the taps call for a #29 numbered drill bit (9/64”); that is 0.136”; this is 0.011” larger diameter than the 1/8” shank limits of rotary tool chucks, so you need to enlarge the holes left by a 1/8” rotary file. Drill, and then file or grind, at one-half speed in your rotary tool.

    Enlarge the hole a little bit with a diamond coated rotary burr. You are removing only 0.006” all the way around the hole’s periphery. So, you want a tool that works smoothly, and just slow enough to keep control of the process. Swing the diamond coated burr lightly around the hole’s edge, and check to see if a taper tap will thread in the hole easily. If not repeat enlarging and checking. Be sure to keep track of how many passes produce the desired result. It is wise to perfect your technique on scrap steel, before enlarging holes in your flame retention nozzle parts.

    There are tungsten carbide rotary files with heads up to 1/4" diameter, so at need, this process can be used for larger screw holes in sheet metal parts.

[swedefiddle]

Good Morning,

Do not drill with a Rotary Tool!!  Use a Drill!! Cordless or Air.  Drilling semi-slowly allows you to push the Drill Bit to stay on Center. If it starts off-center, it will stay off-center. You have a chance to move your Drill Bit to center, Only When You Are Starting the Hole!!!

I use Jet Drills (for drilling Carb Jets and Forge Burner Jets), Metric and Number, for drilling the specific Jet Size for the Burner. I always use a 'Pin Vice' in my fingers, NO POWER TOOLS!! when drilling Jets.  I am one of the 'Old School' Ol'Goats, that has Jet Drills, Jet Tapered Reamers and Jet Micrometers. No, I don't remember where I bought them. You have to keep your eyes and ears always open, to find them. They show up at the oddest times and if you don't say yes, they are GONE!!

Yes, you can Solder up a Jet and drill it smaller. Yes, you can solder up a Mig Tip and make it whatever size you want. The Mig Tip should NEVER get hot, in use. It has cold gas going through it and cold air around it!!

Neil

 

 

[Mikey98118]

Good afternoon, Swedefiddle.

To begin with, I don't disagree with a single thing you said. We are coming from  two different concerns. I am only thinking about drilling pipes tubes for socket set screws, and should have preference my statement with that limitation. Also, the discussion of how to use a rotary tool, to do the job of a hand drill, is only for the sake of people who shy away from buying two different power tools, to build something they feel tentative about, already. In other words, it is newbie bait

  I only hope that more people will totally disagree with me, and tell us about their way of doing this work. And while I do not drill gas orifices, I will still be going back over your methods, to memorize them. There is no such thing as useless knowledge; only stuff we don't want to use, today. However...first, a big cup of java

[swedefiddle]

Good Morning,

Thank You and Your Welcome!!

The hardest thing to understand is, "Common Sense is not Common". LOL

Neil

[Mikey98118]

I love hearing the private methods guys have come up with to do their work; spent decades dreaming up my own

[Frosty]

The "common" in "common sense" has nothing to do with how wide spread it is, it is a measurement of grade. Say a common nail as opposed to a ring shank or glue coated, etc. In the common usage of the phrase common means, Nothing special, doesn't require special study, skill, etc. Another way to say it is "nothing special sense". . . but that's pretty awkward. 

When I drill out mig contact tips for jets I chuck the mig tip in the drill and clamp the drill bit, reamer, etc. in the vise. Envision a vertical axis lathe. Aligning the drill bit is the touchy part but easy enough to do. Simply insert a drill bit that fits the mig tip without moving sideways in the vise and adjust until you can run the drill press feed up and down easily.

I use my drill press to keep everything aligned precisely when making T burners as well, all the prep work necessary on the T fitting is to grind or file the parting line smooth and center punch it. EZ PZ

Frosty The Lucky.

[Mikey98118]

Thanks, Frosty. Any more of you people out there, willing to share?

[Latticino]

Do this sort of work very rarely.  I use an old Unimat SL1000 in lathe mode for this, if needed.  Can be set to be fairly precise and with a decent drill bit you can get a good orifice.