Burners 101

[Trevor84]

Hey Mike the left burner wants to blow like crazy, the burner I have to choke like foghorn and the weasle. 

 

The burner on the right seems to react like normal in a cold or hot forge while adjusting choke and as the forge heats up you can open the choke and the flame reacts normal looking. 

 

The left burner wants to blow the flame right off and all over the wall across from the burner ignites like a magician chucking a blue fire ball. No slow sloppy blue flame but as if the burner want to blow through the wall. 

I'm trying to upload a video I to YouTube to share the link. 

 

 

 

 

[Trevor84]

https://youtube.com/watch?v=UIRp5VJrQqM&si=EnSIkaIECMiOmarE

The left side reacts the same whether the brick is in place 

https://youtube.com/shorts/wcusMZY5Gz0?si=EnSIkaIECMiOmarE

 

Sorry I moove so much. 

 

Using a needle valve on each burner makes a lot of sense, good point ☺ 

[Mikey98118]

This video makes it clear that both forge ends can be open an equal amount. Therefore unequal back-pressure cannot be the source of your burner problems, and back-pressure at all is nearly as unlikely, as a source.

But the video also shows that your burners are running rich. Therefore, I still advise the suggest improvements. Un the other hand, they aren't running as far off as I figured, so the beveling should do the job for you.

I suggest a little kit of tungsten carbide files, which can do the job, even in an electric drill. If you are willing to buy a rotary tool, then diamond encrusted rotary files will do smoother work, almost as fast.

[Trevor84]

Tungsten carbide files, that makes more sense than the diamond ones. 

 

 

[Mikey98118]

At lower speeds, yes. At 30,000 RPM even 1/8" diameter tungsten carbide files try to kickback a lot. Surprisingly, diamond encrusted rotary files are nearly as fast, and leave a way smoother surface behind, because they aren't inclined to kickback, at 30,000 RPM. If you are mainly concerned about how much you get for how much you spend, the tungsten carbide rotary files are the way to go. If you only have a drill to spin them in,  tungsten carbide rotary files are the way to go.. I have no dog in this race, owning several packs of both kinds.

[Mikey98118]

Latest 2" cordless angle grinder? Maybe not.

Bosch Cordless CUT & GRIND Mini ANGLE GRINDER is the latest 2” 7.2V angle grinder found in the market; it is presently offered on eBay and on Amazon.com for $81.43 (a two year warranty is included). I feel that their high price is due to buyers desire for quality assurance. But this is quite possibly the same product that is being sold under the SHENHAOXU label for a lot less money…

So why be so keen on them, anyway? Because they can do even more delicate surface cutting and beveling tasks than the 3" cordless angle grinders. Tube burners, with three rectangular air entrances to be surface cut into ever smaller mixing tubes need ever more delicate power tools, if we want to do neat and tidy work .

If you want the best possible performance from miniature burners, your work MUST be neat and tidy. I've seen perfect flame envelopes generated from pretty ragged looking 3/4" burners; don't expect that happy result in 1/4" burners.

[Mikey98118]

The Bauer 20v 3" cutoff tool (available from Harbor Freight Tools for $50) is a burlier version of the of 12V 3” angle grinders. You trade handiness on delicate tasks for extra power; double strength batteries can also be added. This is one of the latest 3” angle grinders with close to the power to be expected from a 120V power tool. Worx and DeWalt brands also have 3” tools in this power range. More brands will probably be added in the marketplace.

    What then is the point of this tool? After all, there must be a point to it, if competing brands are proliferating, right? The point is all the power needed to be a practical workman’s tool, but not too much power for safety, when surface cutting; this is why they call it a cutoff tool, and not an angle grinder. All of these new power tools are used for both jobs. While it is considered hard to make an angle grinder too powerful, it is easy to make a saw unsafe, if overpowered; this is because of the danger of severe kickbacks from overpowered hand held saws. But powerful hand held saws have been used for over seventy years, right? Yes, but for cutting wood--not steel.

[Mikey98118]

The difference is positioning. If you plunge cut steel with a chop-saw, it can be done safely. If you put a friction blade on a circular saw, you can cut steel safely, so long as you keep its bottom guard flat upon the work surface. But surface cutting on curved surfaces, free hand style is likely to create kickback. Then is when too much power in you saw’s motor is likely to be paid for with your blood.

 

[Jake18]

I don’t know if you’ve talked about it already, I’ve done some reading but I have a question about the forge door’s effect on the burner, or the back pressure. How does this work? I would imagine that the opening being too small creates pressure in the forge , effecting the transition from the high pressure of the burner to the low pressure of the forge, and doesn’t allow air to come in with all the exhaust gas coming out. Correct me if Im wrong please, and I’d also like a better understanding of the physics of it. But how does a large opening affect it? 
Also, thank you for all the information you put out there so that we can learn, it’s greatly appreciated.

[Mikey98118]

We all thank you back, for wanting to lear

You have it right. It isn't all that different from the need for a tail pipe on your car. All that gas needs to be exhausted, or its engine shuts down. NA (naturally aspirated) burners are more easily affected by back-pressure buildup in the forge's interior than fan-blown burners are; its a lessor concern with them. And yes, it is the inducted air in the burner that gets interfered with, because back-pressure will shut down the burner long before it could start interring with incoming fuel gas.

A couple of decades back, we were all agonizing over how large or small to make our front forge openings; too large and a lot of heat was lost; too small and back-pressure interfered with the burner. Being old enough to appreciate that cheating is the best path to victory, I decided that variable was the perfect size.

So, I started recommending variable baffle walls, as the answer to this question. Please understand that there were probably loads of people who stumbled across this answer already; they just weren't talking about. So, being a lifelong blabbermouth, I did

What is the very best form of baffle wall? It sears my perfectionist heart to admit that 2" x 4" refractory bricks is. Ugh! What a bad taste taste in the mouth; yuk! How can I ever get people to go for hinged and latched doors with interchangeable high alumina kiln shelves (with different cut openings for stock) ever again?

Surely, there must be a few mad scientist perfectionists left (that I can sucker down to the deep end of "the people's pool") left somewhere? It gets lonely down here. Hey! The ice-water is fine; really...I wouldn't lie to ya--much  

[Mikey98118]

"...lear" ? Hilarious. I meant to write hear. Its a good thing I enjoy a good joke; having to face it in the mirror every morning

[Mikey98118]

A proposed homemade miniature angle grinder to rotary tool chuck adapter

This is a proposed construction plan--not a fact. I have purchased the drill bits, taps, angle grinders, and two JTO chucks. At present my project is being interrupted by a week or more in a hotel room, while the bathroom shower area is being remodeled .

At present, you must build this attachment yourself; eventually, something like it will be marketed. Whether that happens in a couple of years or a couple of decades, who can say? If you want to wait for some OEM to market an obviously needed attachment, which would save you the expense of buying two of their products, instead of just one, go right ahead. It took seven decades for manufacturers to finally market a see-through safety shield for rotary tools. Safety shields didn’t interfere with sales of other power tools; they just couldn’t be made to cost a lot.

    The first thing you will need is a JTO size drill chuck; this is probably the smallest size keyed drill chuck on the market; they have opening ranges from 0.3 to 4mm (0.013” 0.156”); a comfortable range for use with rotary tool accessories. Several importers and drop shippers sell miniature Jacob (keyed) drill chuck kits for around $10 through Amazon.com, and other online sources).  

    These chucks are small and tough enough to be run at the speeds suitable for use on 3” and 2” cordless angle grinders; they are normally mounted on DC motors, and used as miniature drills. It is common to find them sold with brass JTO to 1/8” mandrels for mounting to DC motor spindles.

Brass Collet Chuck sets had been employed on pin vices for decades, and now are used on DC motors; they consist of threaded mandrels, collet clamps, and threaded caps. being much smaller than any Jacob chuck, collet chucks can be spun as fast as any power tool you are likely to find. Being solid brass, they don’t rust. Being small, they are an attachment that takes up very little space in a tool kit. Brass collet chucks can be changed over just the same way as JTO keyed chucks are, and you can buy them in three chuck kits for less money than a JTO chuck, giving you three chances to get the work done right, for a smaller investment. They are sold on Amazon.com. So, what is their down side? Some sets come with cheap thin collet clamps; then you must buy a good set of collet clamps for another five to seven dollars, to avoid run-out.

Caution: Not all of these chucks have threaded mandrels with 1/8” holes for mounting on DC motor spindles. There is a newer version that is meant for mounting directly unto most (not all) rotary tools; this consists of a threaded cap nut and several collet clamps only, and are quite useless for this purpose.

Both the 12V 3” and 7.2V 2” angle grinders employ the same M5.8 threaded accessory mounting bolts, which screw into a rotating plate; these grinders don’t have a threaded spindle. This clever departure from the usual arrangement is what makes this attachment practical to build. If you are set up to enlarge the mandrel’s existing hole to 4.2 millimeter/s, while keeping it centered and parallel to the chuck’s axis, and then tap M5.8 threads into the mandrel’s enlarged hole, a screw can be run into the chuck’s mandrel; then its excess length cut off, and the end of the remaining thread filed to keep it from cross-threading in the angle grinder plate’s mounting hole.

    If you’re good with tools, you should be able to do an acceptable job of drilling and threading the mandrel on a drill press, with the mandrel inserted in the JTO chuck, and the chuck held in a press vice. Otherwise, use a lathe for the work.

    You will find that customers of these chucks often complain about run-out, when employing them on a DC motor. The problem isn’t poor quality control on the chuck, or its brass mandrel. The mandrel’s design is simply too short to assure accuracy on a motor spindle; this problem will be bypassed by your modifications to the mandrel.

    Installing a threaded screw into the mandrel allows a loose fit, unless you screw the thread in completely; check for movement to ensure that you don’t.

    Screw the thread completely into the angle grinder, and then screw on the drill chuck, until it touches the grinder’s rotating plate. Insert a long drill bit into the chuck, and spin it, to check for run-out. If no run out is seen, continue finishing the attachment. If you have more run-out than is acceptable, the simple solution is to face off the end of the brass mandrel in a lathe. The hard and slow solution is to check to see what direction the drill bit in leaning toward, ink mark it, and correct the face plate by running it over #400 grit sandpaper, while frequently remounting the mandrel to check for changes, until the run-out is gone. Next, secure the thread in place on the mandrel with hard setting Thread-locker; be sure to give it time to set up. Grind or file off a little more the thread end, so that it no longer bottoms out in the grinder’s face plate hole; this provides added assurance that the parts will run true, as the slack between the bolt threads and those in the tool’s threaded mounting hole should allow the chuck to perfectly match surfaces with the grinder’s face plate.    

    Thereafter, the chuck can be mounted on either one of these small angle grinders, using the chuck’s key as your wrench. You should then be able to employ your angle grinder as a perfect little angle head rotary tool.

    You may have noted that this attachment is called a rotary tool chuck adapter; not a drill chuck adapter. 3” angle grinders spin way too fast for use as drills (19,500 RPM). At present, 2” angle grinders run slow enough (6000 RPM) to occasionally be used as drills, depending on what material is being drilled, and by what bit diameter.

    All of these imported JTO drill chucks, like most USA manufactured chucks, are machined from low-carbon steel—not stainless-steel. You will either keep them oiled and dry, or they will rust.

 

[Mikey98118]

This idea is not proven yet. There is plenty of room for naysayers...

[Jake18]

haha, cheating definitely helps sometimes. And i guess bricks are just too easy. Maybe i'll do the hinged alumina shelves for the next build. Looks fancy ya know. And i don'y knopw if i would call myself a perfectionist but i do appreciate getting it right to the rightest it can be lol.I was in the process of designing a forge until i found this forum then became paralyzed in my progress by my desire to find the best way to do everything. It is quite frustrating as i have many projects i haven't started because i am trying to find the best way to do it. This summer when i have more time to tinker i'll probably be doing alot of expirementing with forges and burners. I guess expect to hear alot of questions then lol.

[Mikey98118]

The single weakness in gas forges is that, to be really efficient, people learn that they will need more than one size or shape forge. The only gas forge that qualifies on this score, is a Frosty-pile-of-brick forge, but while they can be made efficient, they will never be anyone's first choice for traveling for demonstrations.

This is just one more reason to make your first gas forge a mini-forge. Also, you will realize that, no matter how well you design that forge, you will come up with numerous improvements to make on it, once it's too late. Some of us have been making gas forges for decades, and it still happens every time we make our latest 'perfect' forge

[Jake18]

Yeah I was one of those that used to think that bigger was better to a certain point. Since then I’ve realized that you don’t need anything big. Most of it will be a waste if you’re not actually working what all you’re hearing up. 
And I guess that is one of the good and fun things about it. There’ll always be improvements to make and something to work on. Keeps us busy.

[Mikey98118]

From childhood, I thought that I loved building things. In old age it has become clear that what I loved was mastering, and playing with tools.

How about that! From hardheaded tradesman to geek in one uneasy lesson 

[Greg in Maryland]

Mike,

I just joined and this is my first time posting so here goes.  First of all - Thank you for the awesome topic.

I have a 3/4 T Rex burner and must admit I just discovered how poorly it was running/setup after finding your page.

 I replaced the flared burner nozzle with a straight nozzle (1” schedule 40 stainless pipe).  This was due to the flared nozzle being destroyed from use.  I played with the overhang and settled on 1.125 inches.  However , I can’t seem to eliminate the secondary flame to an acceptable amount.

Would this burner benefit from squaring the air intake slots and providing the 60 degree relief to the interior?  I did a little experiment by introducing some compressed air into the intake and it reduced the secondary flame to something acceptable.  It did lean the flame out and it was hard for me to determine it I could correct for that with a choke adjustment.

The picture is where I have left off.  I believe that was 15psi.

Any and all feedback is appreciated.

Regards.

[Mikey98118]

You asked "would this burner benefit from squaring the air intake slots and providing the 60 degree relief to the interior"?

Before we get involved in what is actually wrong with your burner, the answer is "yes, that would increase its power." Especially modifying the front of its air slots; not so much their rear edges.

However, the modification won't improve burner performance much, until you change the burner's flame retention nozzles; they have been named "slide-over step nozzles" for a reason. Every nozzle, of whatever burner size, has a an inner spacer ring, which allows it to slide back and forth over the burner's mixing tube. The outer portion of the nozzle has a spacer ring, usually 1" long, inserted in its rear end. What it looks like in the photo, is that your burner's nozzle has no spacer ring. If so, you need to buy the next larger size pipe or tube size, and insert a 1" long section of the present nozzle in it as a spacer ring.

Before I started building slide-over step nozzles for burners, tapered nozzles were standard; they were tapered  to about  the same amount of increased diameter as is gained with the addition of a spacer ring...

I know that stainless-steel has become expensive, and you probably don't look forward to buying more of it, to begin all over again. However mild steel pipe nipples are still pretty cheap down at your local hardware store. For a few bucks you can buy the parts to slap together a temporary mild steel flame retention nozzle, to test out what I write here; it will last a month or so, while you build the real deal

Any more questions? Just ask. Someone else will want to know the same answers too.

 

[Greg in Maryland]

Mike,

Appreciate the feedback.  I will construct the slide over step nozzle and report back.

Regards.

[Greg in Maryland]

Mike,

I tested the slide over step nozzle.  I had to overhang the nozzle 2.5 inches to get the secondary flame seen in the attached.  I used a 1.25” schedule 40 pipe for the nozzle (3” overall length) and a 1” schedule 40 for the spacer (1” overall length).  15psi on the pressure.  Thank you in advance for your feedback.

Regards

[Mikey98118]

Well, the flame is improved, but you're not there yet. If your nozzle is 3" long, and its spacer is 1" long, this only leaves 2" of overhang available, without creating a double shoulder area past the end of the mixing tube; this will weaken the flame. It has been over twenty years since I built one of these particular burners, so I can't swear that its overhang is exactly like I use nowadays, but it's likely.

So, hear is how I compute the amount of overhang. The length that the nozzle sticks out past the end of the burner tube should be as long as its inside diameter is wide, plus 1/8"; this additional distance is all that is used to soften the flame just enough to keep it stable. You tune the nozzle within that distance only. By the way these, and every other burner I design, have zero secondary flame, when tuned perfectly. Some guys deliberately de-tune them a touch, in order to maintain the slightest feather of secondary flame. I'm speaking of perhaps 1/4" thick of secondary flame envelope to ensure that no scale is created, while the work is heating in the forge. Just try tuning your burner this way; you will be glad your did.

Well, what if you can't get the promised performance with the overhang kept within these limits?

Then, it is time to see what is wrong with other parts of the burner. Is the MIG tip the correct size and length for this burner, and is its gas orifice clean (no tar or waxy buildup)? Looking at the photos of your flame, it is clear that none of the burner parts as out of axial alignment, at least.

By the way, congratulations on choosing fairly thick tubing for the nozzle parts; they last a lot longer that way.

Socket set screws are easier to live with on burners. Whatever screws you choose for the flame retention nozzle, be sure it is stainless-steel. anything else will oxidize in place, and must be drilled out to change nozzles; just don't go there

[Greg in Maryland]

Mike,

Yes - I did have a double shoulder area past the end of the mixing tube with the 2.5" overhang.  The appropriate overhang should be 1.5 inches.  The pipe id is 1.375 plus the .125 puts it at 1.5.  I initially set up the slide-over step nozzle for a 1.5" overhang with no double shoulder and the results were unsatisfactory.  The secondary flame was very prevalent.

Addressing the items you suggested troubleshooting:

I bought the burner new from Rex and have not made any modifications other than needing to replace the flame retention nozzle.  It comes with a 14-T .035 tweco tip.  I will verify the orifice is in specification.

I gently probed the orifice with a welding tip cleaner to ensure it was not obstructed.  I blew out the assembly from the fitting end (disassembled it from the valve).  I will submerge the tip in some mineral spirits in case there is any wax/tar buildup that I did not recognize.

I included some additional pictures for reference.  One thing I did do that might be worth mentioning is I had to remove about 1/4" off the end of the mixing tube because it was degraded (probably from my lack of understanding that it was not set up properly and it was running poorly).  I dressed the end so that it is perpendicular to the tube.

Finally:  I do own your book and appreciate how well it is written.

[Mikey98118]

I don't see any obvious problems in those photos. So, now we need to jury rig the burner, and try to simply make an end-run around its poor performance. I would start with the same tip in the next lower size; they don't cost much, and this change might solve all your problems in one go.

[Mikey98118]

Offers for 3" x 3/16" x 3/8" grinder discs are also available through Amazon.com; all of these offers come and go. So look down the page, if you’re not satisfied with the first advertisement you find.

    Spacer rings can be cut from plastic, to center grinding wheels  

(With 3/8" center holes) on angle grinders with 5.8 millimeter mounting screws. 2” and 3” Roloc  plastic backed flap discs can be center drilled with a 5.8 bit, and no spacer is needed. Also, Roloc flap discs are far less expensive than discs with 3/8” center holes in these small sizes.