Burners 101

[Mikey98118]

Tuning the burner

Turn the gas flow on just a little way, and ignite the burner, immediately turning the gas pressure up high enough to blow any internal flame forward onto the nozzle. Otherwise, the flame can “burn back” into the mixing tube (until the gas pressure is finally increased), rapidly overheating the burner. In case of overheating, you must shut the burner down and allow it to cool sufficiently before igniting the burner again. Once the flame nozzle is heated enough for the nozzle’s stainless steel to start turning colors (like a chrome motor cycle exhaust pipe), open the needle valve up completely, or increase the regulator pressure up where you desire it.

    Practice lighting the burner several times outdoors, but in a shaded area (propane flames become nearly invisible in bright sunlight). You need to play with the burner for a few minutes, moving that hot flame retention nozzle back and forth on the mixing tube to produce the cleanest possible flame. I like to leave the long part of an Allen wrench in one of the socket set screws, with the screw kept just barely snug, for easy unlocking and movement without burning fingers during this phase of tuning.

    You are looking for a light blue flame, with a single wave front, no white inner flame behind the wave front, and little to no outer flame envelope (secondary flame) beyond the primary wave front. The outer edge of the flame is called its “envelope”; it is also known as the wave front. Why would the whole outer edge of the flame be called a wave front? Because gas flames burn from the outer edge inward. If there is more than a single flame envelope, each one; primary; secondary; and tertiary, will do the same.

    When the flame retention nozzle has too much overhang, the flame will soften; a secondary flame will form and grow. Shorten the amount of overhang until the secondary flame disappears; at this point your burner has a neutral flame. Now shorten the overhang more, and watch the flame color turn darker blue; it is gradually leaving a neutral flame and becoming lean (oxidizing); with some burners, the flame will snuff out almost immediately, instead. Other burners can create a highly oxidizing flame before it is snuffed. Lengthen the overhang again until the secondary flame starts to appear, and adjust the nozzle back to just where the secondary flame vanishes; that’s where you want to keep the overhang; lightly tighten all screws.

Now, move the gas tube and MIG tip back and forth to find the burner's sweet spot; this final step allows you to fine tune the burner just a little better than moving the flame retention nozzle did.

    Do not be surprised or concerned by thin yellow, orange, or red streaks in the flame, which can develop after the nozzle heats up sufficiently, or immediately if you didn’t clean all debris from within the burner’s parts; they are caused by a reaction between the super-heated oxygen and the and the stainless-steel of the nozzle (much more prominently from #304 stainless nozzles than from #316), and by other burning metal debris.

    As you become thoroughly familiar with your burner, its sounds will also tell you much. This is handy when the burner’s flame is hidden within a forge or furnace.

    Heated gas rises, and it will enter your air intakes when the burner is held near enough to the vertical down facing position, destabilizing the flame (this can only happen if the burner is connected to fuel hose; otherwise, a canister may dump liquid fuel into the burner before you reach that point, causing even worse problems). Practice bringing the burner to this position and then backing it off, until you feel confident of your understanding.

    If burner performance suddenly declines, check the gas orifice for a buildup of tars and waxes. Clean the gas orifice, using a set of torch tip cleaners. Because of the small diameter of the jet, this problem is common. Much less common is debris in fuel hose, valves, or regulator, but it has been known to occur.

    Minimum gas pressures should be 4 PSI on this burner, and the flame should be stable beyond 30 PSI

    After all tuning is completed, including final tightening of the set srews while the flame nozzle is incandescent, mark a spot 1/2” forward of the nozzle’s rear edge; drill and thread all the way through the flame nozzle, spacer ring, and mixing tube for a locking screw, which will ensure that the nozzle cannot slip out of position in hot equipment during heating cycles. Screw in a 1/2” long set screw, and ink mark the threads protruding into the flame retention nozzle. Remove the screw and run its nut up to just beyond the ink mark. Cut and file off the excess thread, run the nut over it, and sand the screw’s face to remove any burr from its thread end. Replace the screw in the nozzle.

    If you wear out the first flame retention nozzle, don’t attempt to use the same hole in the mixing tube with the new locking screw; it will be close to impossible to match up the threads in the new nozzle to the existing threads in the mixing tube. Drill a new hole somewhere else.

[Mikey98118]

MIG tips for 0.025" welding wire is what I recommend these days for 3/4" Mikey burners. When the book came out they didn't exist. MIG tips for 0.030" welding wire is what I recommend for 1" burners. I know you stated that your burners were 1" size, but they look like 3/4" size.

The inside diameter of 3/4" schedule 40 pipe is about 7/8". Do you want to check your burners to see which size they actually are?

[Jimw3326]

Great info, thanks. The existing retention tubes were placed where the flame looked best then welded. I can't tell exactly how long it was since it eroded away.

The inlets are beveled but I'm not sure about the angle.

[Frosty]

You got the inlet bevels backwards, you want them to act like an entrance ramp so air will enter more smoothly. 

Frosty The Lucky.

[Mikey98118]

Frosty,

If you are talking to me, I wrote: "Next, you want to grind a sixty degree internal bevel on all those squared ends." That is correct. Perhaps I should also have written: This leaves the bevel's knife edge on the tube's outer surface. But really; calling for an internal bevel in the air openings forward ends should be plain enough, yes?

[Frosty]

Nope, I was only restating the physical direction of the bevel in simple language with only the barest minimum reason. I explained why I do this in the other post I just submitted. 

Sometimes a long detailed explanation isn't so helpful when it's a simple is the issue. I know, simple issues can have complex consequences but those can be discussed later just as well. 

Frosty The Lucky.

 

[Jimw3326]

14 hours ago, Frosty said:

You got the inlet bevels backwards, you want them to act like an entrance ramp so air will enter more smoothly. 

Frosty The Lucky.

The bevels are on the inside. It might be a little hard to see in the pic, but being a pilot, I do understand air flow a little.

[Frosty]

Oy VEY! I had to go back and look again, the picture was so clear I was sure I saw what I saw. Soooo, I just realized I was looking at the far side. 

I'm going to put my dunce cap on and go sit in a corner now. Please disregard my previous posts on the subject.

Frosty The Lucky.

[Jimw3326]

No worries mate, dunce cap has my name on it.

[Mikey98118]

16 hours ago, Jimw3326 said:

The inlets are beveled but I'm not sure about the angle.

Even though I'm an infamous picky...sixty degrees is just a suggestion to get the idea across that the steeper the angle the better. Let common sense rule the matter.

 

1 hour ago, Frosty said:

I'm going to put my dunce cap on and go sit in a corner now

That's my spot, and there's no more room for you.

[Frosty]

Gentlemen take your corners? HAH, this one is mine, MINE I SAY!

That reminds me I have to find my Santa hat, tonight is Christmas costume Curling. No pillows necessary I can do the shakes like a bowl full of jelly just fine. Better , the temp is coming up with the next storm rolling in so the rink won't be so danged cold.

Frosty The Lucky.

[Mikey98118]

So, what diameter and length gas orifice are you using in the burner?

[Jimw3326]

Mikey, It's a Lincoln 350A. tip I modified. It was .045 tip (.050 maybe) that I welded the end and re-drilled to .032. Then I threaded the back to 5/16-24 to thread into the 3/8 brass tube that I threaded. The exposed tip is about .5 and overall is .8.

The pic posted here is of my first one, second one uses a brass tube and is much cleaner.

[Mikey98118]

The "through-hole"; a tunnel shaped forward area of MIG contact tips, is typically 1/2" in length.  How long do you suppose your new drilled hole is? Why this matters is that the through-hole section does more to accelerate the gas column exiting the MIG tip then all the rest of the tip's length. This tunnel also stops the spin that the narrowing portion of the rest of the tip would otherwise create in that gas column; it would otherwise reduce column's effectiveness at air induction into the burner.

[Jimw3326]

Wellll..... In my defense, I made it about 7 years ago before reading up on the latest and greatest. I now have in my anxious hands some long taper tips to replace those, they're 1.25" nose to thread 1.75 OAL. Also, I'm going to try to modify the intake to get a little more swirl going on. I'll post up some pics when I get there. I'll be off work for 10 days coming up and I hope to have the forge completely rebuilt by the new year.

[Frosty]

Naw, nothing to defend Jim, we all try stuff and some "mistakes" turn out to be golden just maybe not for what you were intending. The long tube also columnates the gas into a laminar flow so it forms a more uniform and smooth "cone" as it enters the mixing tube and produces a strong low pressure zone which induces the combustion air into the air ports.

Some of us went through phases where we didn't have much else to think about or tinker with.

Frosty The Lucky.

[Mikey98118]

11 hours ago, Frosty said:

Some of us went through phases where we didn't have much else to think about or tinker with.

Frosty has it right, Jim. I am not smart or well read, but have simply been thinking about this stuff for twenty-three years 

[Jimw3326]

I think I'm about to enter this phase!

[Frosty]

Welcome aboard Jim! We got us another one Mike Mwahaha!     

Frosty The Lucky.

[Mikey98118]

Igor will be so glad for the company

[Mikey98118]

 

Mounting a homemade side handle

Have a merry--and safe--Christmas

Rotary tools and die grinders can be braced for straight travel (similar to 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 for surface cutting. Twenty years ago, 2” angle grinders like Proxxon’s Long Neck Angle Grinder, or the Merlin 2 from King Arthur Tools, were the only power tools that could easily make straight line cuts in small burner parts; they were designed for inline motion, and had steel safety guards. Any rotary tool with a side handle mounted, can now do a faster job, more safely, for a small fraction of their prices.

    What has changed, to make this advance 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 looking past steel guards. But you can place your disc just short of 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; not at right angles, for better control during a surface cut.

    Most hand-held rotary tools have a threaded plastic collar that is protected by a plastic cap (AKA front cap; nose cap; housing cap) around the base of the spindle. These rotary tools have a threaded neck diameter of 3/4”; this is the area that a sheet metal side handle sets on, trapped between the threded collar and the tool housing’s plastic shoulder. Dremel popularized those same threads to securely mount attachments, such as their flexible drive shaft, and other manufacturers copied Dremel. The threads on clear plastic safety shields. It is easy to buy a 3/4” flat washer. The flattened end of a 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. The plastic shield, securely traps it in place, when needed; or it can be quickly removed, when it would be in the way.

    Why bother? Because wrist movement can’t be braced anywhere near as effectively as inline movement (which only becomes practical with the aid of a 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—not 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 the likelihood of 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.

Caution: Whether or not a handle improves the safety of your rotary tool, depends on power switch location and type; that can’t be listed for every model, since there is such a variety of on/off switch designs and locations. Mounting a handle will increase stability as you cut. But, stopping the tool before lifting a cutting disc from the kerf is also considered “best practice.” It is good if the switch type and location allows this, with side handle added. if switch type or location makes that impractical already, then no safety is lost by adding a handle. If the switch can be safely used to stop the tool during surface cutting at present, but adding the handle would change that situation, leave it off; this is quite unlikely, but still conceivable.

The main point of a side handle is to help in surface cutting, but cutting with an electric die grinder must be done far more carefully than with a rotary tool:

(1)  Any safety at all 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 a cutoff disc to the work surface.

 

(2)   A high-power die grinder (400 watts or more) should be run at half speed during surface cuts. A medium-power die grinder (no more than 230 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 handle.

 

(4)  The disc must be breakable; a resin-based friction disc; and thinner is safer than thicker; it isn’t less likely to break of course, but will be 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 flung about near your body. Don’t kid yourself that you’ll always avoid kickback; that’s not in the cards.

 

(5)  The 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” cutoff disc; better safe than sorry.

Safety, is seldom an absolute, except in the negative sense. “Just don’t 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’re cutting on flat surfaces, yes. If you’re cutting off the ends of angles or pipes, the saw still maintains an advantage, so long as you pay close attention. When cutting air openings into pipe or tubing, no. If you’re cutting into curved surfaces on cylinder ends, to create equipment shells, no.

    When grinding, sanding, or 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 is likely 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 and brass. 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.

[Mikey98118]

Fuel Gas Pressures

Harking back to tuning burners: Every burner size has a minimum gas pressure needed to create a stable flame, and a maximum pressure, beyond which the flame starts losing peak performance. Furthermore, minimum fuel gas pressures vary more widely than maximum recommended gas pressures in different burner designs.

Frosty "T" burners probably have the lowest fuel pressure ranges available of any burner type, followed by linear burners, and my high-speed tube burners have the least variance in low end range.

[Mikey98118]

On 12/31/2022 at 6:20 PM, Mikey98118 said:

and my high-speed tube burners have the least variance in low end range.

And that happens to be around 4 PSI; varying very little by burner size.

[Mikey98118]

On 12/21/2022 at 10:31 PM, Jimw3326 said:

I now have in my anxious hands some long taper tips to replace those, they're 1.25" nose to thread 1.75 OAL.

That sounds just fine; excellent in fact; do they have 1/4-27 threads (or else what is the thread configuration) What is the brand name? It would be good for others to switch to these tips, too

Someone is sure to ask, "is tip length all that important?" How important usually depends on how small the gas tube that feeds it is; the larger the tube the more important. But an extra 1/2" of tip length can also be crucial in tube burners that are screwed existing air/fuel torch-heads, in order to end up with enough length in the air openings.

[Jimw3326]

On 1/7/2023 at 4:46 PM, Mikey98118 said:

That sounds just fine; excellent in fact; do they have 1/4-27 threads (or else what is the thread configuration) What is the brand name? It would be good for others to switch to these tips, too

 

These are Bernard tips and they have a weird thread that would be approximately 5/16-8. Like I said.....weird. What we have at work are .045 (.050) & .035 (.040) so I have some 1/16 brass tube with an id. of .033. I drilled out the .045 tip to accept the tube snugly and tapped the inlet end with a center punch to flare it. Re-threaded the tip to 5/16-24 to fit the existing gas tube. Since you said the tip needs to be long enough to straighten out the flow, another thought exercise, I took one of my previous tips and put the tube in it also the same length as the taper tip. I'll also grind the new one to a taper and see if there's any significant difference. I'm also going to put some swirl vanes inside the tube just behind  the tip and see what happens.