Burners 101

[Mikey98118]

All things have their limits, beyond which, something good just goes to far, and turned sour. Vortex burners are souped up linear burners; as such, they are something good.

Ribbon burners, and multi-flame burner heads, are also something very good. But all such devices employ one kind of plenum chamber, or another to form those multiple flames.

Plenum chambers seriously lower flow pressure of the gas/air mixture passing through them; so do vortex enhancing burner designs. Either path is good; but they cannot be combined; choose one or the other--never both together!

 

[Hefty]

Oh, I didn't realise they don't mix.  I was actually thinking about basing a NARB on AFBs 3d printed vortex burner.

So, would the further braking force of the plenum chamber cause the already comparatively slower vortex flow of FAM to burn back in the mixing tube?

I guess I could just 3d print a linear assembly, without the vortex vanes.

[Mikey98118]

I should have more exactly defined those limitations. A linear burner with still fan blades would do well enough feeding a ribbon burner head, but not with a running fan with impeller blades. Also a linear burner with flat blades or a squirrel cage fan pushing air into a plenum chamber, would do fine and dandy. But not an axial fine with impeller blades.

    Still impeller blades don't lower mixture pressure enough to create a problem, when the gas/air flow enters a plenum chamber, And fans that push air forward will increase flow pressure before the mixture enters the plenum chamber.

As to the 3D printed burner...I don't think so; it is more effective than still fan blades, and therefore, it is likely to lower mixture pressure enough to create back-firing from the plenum into the mixing tube. I could be wrong, but it doesn't look like a good bet to me.

[Hefty]

That's a fair enough explanation. I was mainly hoping to do it because I had the 3d printed burner already. I can put together a linear or another T burner for a NARB easily enough. At this stage, it's still a round tuit job anyway.

[Mikey98118]

Nothing whatsoever prevents you from using the information in the last two pages to design a modified version of burner air intake for a 3D printer. Circumstances alter cases. Another Frankenburner would be the first one to point out that his design was made for one purpose, and you can make just as good a design for ribbon burner use; a different purpose.

[Hefty]

Yes, and would be my eventual goal. I'm still at the point where I understand the basics and have the skills to recreate burners from known designs but I don't have the experience yet to recognise on my own, for example, that a vortex burner and a NARB plenum may not mix, but I understand why when someone more experienced, such as yourself, explains it to me.

I'm not at the point where I have the time to experiment with modifying designs. The closest I come at the moment is combining parts of known designs and, as in this case, even that isn't always appropriate/advisable.

Not a complaint, just acknowledging that these things take time. I can't be forging things, building a second forge, and designing a burner all at the same time.

[Mikey98118]

When ever you feel like it is time, all of us are willing to advise you; step by step, if you desire it.

[Mikey98118]

The question "which vortex burner design is the hottest" is bound to come up shortly; is it my fan-induced burner, or Another Frankenburner's (thus far nameless) 3D printer model? Mine will produce the most BTU per hour, but his produces the hottest flames. How do we figure that?

Its flames look pretty much the same as any other first class burner's. BUT its flame retention nozzle definitely does not; his nozzle turns yellow out in the open air, while burning propane. Mine only turns orange, burning propane. The only time I got a nozzle yellow, out in the open air, my burner was running running on propylene; that burns about a third hotter than propane.

If you care about fuel costs, flame temperature beats out BTU consumption every time

[Mikey98118]

On 12/1/2018 at 8:49 AM, Another FrankenBurner said:

This experimental burner flame is very straight and longer.  I am not sure if that is good or bad as far as forge use.

This is regarding the flame photo you posted on Posted December 1, 2018. The short answer is yes, becuase it is complete combustion in a single flame envelope, its being longer simply means that it is putting out the same high heat over a larger area, just the same as a short flame of greater diameter would.

The long answer would be that, good or bad in flame size and shape is mostly relative to the size and shape of the equipment it is meant to heat

[Mikey98118]

 

Freeing up jammed accessories: Collet nuts on rotary tools may need to be sharply rapped once or twice with the tool’s tiny wrench, to free up jammed accessories. Unscrew the nut a partial turn, so that the accessory can slide free; sometimes, they will revolve, but cannot be slid forward and removed. What has happened is that the collet, which the accessory’s shank slides into has jammed in place, locking the accessory’s shank together with the collet. Tap sharply, on the end of the nut with nothing larger than the tiny wrench that comes with your rotary tool; this will transmit just enough of a shock wave through the parts, to break the collet’s grip.

    Should a new tool come from the factory with the collet stuck in place, unscrew the nut a couple of turns, and poke the shank of an accessory against the top of the collet (at an angle), to break it loose.

    If you change accessories frequently, you may find relief from dtiking collets with a brass collet nut; brass collet kits, which include 1/8” collets, sell for around $7.00 on eBay and Amazon.com. Just as some collets release better than others, some collet nuts are better too. Most collet nuts fit other spindles, so switching a better collet nut from a less used rotary tool to your favorite, should be an obvious move.

    Many people simply replace the collet nut (and its sticking collet) with a Dremel keyless chuck. Make sure to buy this attachment from Dremel; a cheap look alike won’t work very long, if it even works at all. How clever is this move? Enough that a few rotary tools are now being sold with this kind of chuck, instead of a collet and nut. Nothing succeeds like success.

    That said, even the Dremel chucks are not problem free. Key-less chucks cannot be tightened anywhere near as effectively as keyed chucks, or even collet chucks, and these tiny keyless chucks increase that problem; obviously, your whole hand can tighten a keyless chuck on a drill motor far better, than a finger and thumb can tighten one of these. Some people have ended up using pliers. A drop of oil or lithium grease in one of the jaw ways (the groove they ride in) will smooth performance.

[Mikey98118]

 

What you should know about speed control:

(1)  The first rule for speed control, is do not attempt to adjust speed while a tool is engaged; move it away from the work surface first.

(2)  It is a popular marketing ploy to include inbuilt speed control circuits on compact equipment, such as rotary tools; avoid their use like the plague. If you end up with a variable speed tool, just leave its inbuilt controls on high (in effect, not engaged), and employ a separate router or fan speed controller (for brushed motors), or a brushless speed controller (for motors without carbon brushes). Plug the right type of speed controller onto your tool’s power cord; it will do the job, without any risk of overheating the equipment’s delicate speed circuit, and shutting down the tool, until the burned-out circuit can be bypassed. Speed control circuits on the very cheapest power tools just use potentiometers (variable resistors); as in heavily power robbing. A modern variable frequency drive slows the number of pulses per second in the right kind of DC motor (which is found on most hand-held equipment these days), but not the amount of power in each pulse, so it’s drop in torque is comparatively minor, as motor speed slows. Many of the cheaper inbuilt speed controls are erratic, and give poor control in their bottom range (or none in some settings), long before they fry.

    Dremel mounted the first speed controls on rotary tools; they were cross-slide types. This was and still is a hardier design then the tiny inbuilt circuits on other tools. Dremel has kept these controls low priced, easily available, and plug-in on their oldest rotary tool models; none of which is true of the new speed control circuits. The Dremel #100 has a sliding on/off switch. The #200 model uses a sliding combination on/off switch and speed control; these switches are interchangeable. You can use an external speed control on a #100 because it’s sliding switch only turns the tool on and off. But don’t use a separate speed control on the #200, because it will mess up that model’s own speed control circuit.

(3)  Even with external speed controllers, do not run motors below half-speed for very long, to avoid overheating their windings (ex. just long enough to drill a single micro hole in pipe or tube).

(4)  You can still overheat the motor by bogging it down under a heavy load; even on full speed (and faster on reduced speeds), but it happens slowly enough for the heating motor housing to give warning, in time to let the tool cool off. But, overheating an inbuilt control circuit happens suddenly. Your first warning is usually a dead tool, and then you may notice a little smoke…or not.

(5)  The faster you race a gasoline engine the hotter it gets; it’s natural to expect that about electric motors too. But the opposite is true. As you slow an electric motor down, it heats up.

(6)  Flex-drives complicate motor heating problems, because the faster you run them, the hotter they get. Foredom Tool’s top of the line KTXH440 is set up to run between 500 and 15,000 RPM; these are, by definition, the best of the best. How can we expect a Chinese import freebie to last at 35,000 RPM? So, you have competing needs with a flex-drive mounted on a rotary tool. What to do? Run the tool at half speed, in short bursts to let both drive and motor cool down; use it no more than you must. Does this sound inconvenient? What part of flex-drives don’t really belong on rotary tools didn’t you get?

If you blow a control circuit, do you have to throw away your tool and buy another? That depends; if you are into electronics, it is simple to de-solder the circuit and replace it with a short length of wire. If not, it is still simple, but you will have to buy a soldering tool, some rosin core solder, and some electric wire of the same gauge (size) or larger than what was used in the circuit; the cost will be about equal to replacing the tool, but you’ll end up with a repair tool out of the deal. Your “fixed” tool will only run at full speed, unless you use a separate speed controller, but that is what you should have been doing in the first place. The separate speed controller can also be used on many other tools.

Speed controllers for brushless motors: Most speed controllers are designed for motors with carbon brushes (brushed motors). Brushless motors (BLDC) need brushless speed controllers; they aren’t hard to come by, or expensive. But there are no plug and play versions available for hand tools; at present they’re only available as kits. The easiest kits to deal with have all the electronics contained in a perforated metal control box, to which you must add electric cords and/or wires; one set incoming from your power source, another outgoing to the tool; wire a receptacle to it (if you want to plug in two different brushless tools at once), or use the last few inches of the extension cord you probably just cut off to make a lead to the power source.

[Frosty]

AMEN to #1 & 2!

Frosty The Lucky.

[Mikey98118]

 

Maintenance dos and don’ts. Before running your new rotary tool, die grinder, or micro-drill, be sure to understand its limitations. Most people treat a beat-up old car better than their brand-new power tools. Read and understand the owner’s manual; if there isn’t one, read the manual for a similar tool online.

  Don't force a rotary tool, by applying pressure against the part surface. Accessories  don’t cut or grind any faster when you apply pressure; they work slower, so you’re  heating up the motor for nothing. Simply maintain contact with the work surface, and let the accessory do what it’s designed for.

Don’t use an extension cord that isn’t rated for the equipment (rated to supply sufficient volts for its length). Follow the equipment manufacturer’s recommendations; otherwise, you create a drop in voltage to the motor that will quickly overheat it, in a similar way that forcing the tool does.

     Don’t press micro-drills hard against a surface, or you will overheat them; pressing high power die grinders, a reasonable amount, is okay, but don’t press medium power die grinders. What constitutes a reasonable amount? You don’t hear it slowing down the motor.

Don’t use damaged accessories; when they break, the heavy vibration of their  uneven loads do the motor and bearings no good. But aren’t ball bearings super tough? Yes, but the plastic tool bodies they rest in are not; damage to the plastic motor housing, and delicate electrical parts, can accumulate, until it is sufficient to over-stress those parts. Better tool designs have fat rubber boots around rear bearings just to slow that kind of damage. Why not on the front bearings too? Equipment designers know, but I would just be guessing.

    

Don’t run a tool below half-speed for more than a minute at a stretch; you will greatly heat the motor up during that period; if you heat it very much, you can melt the solder in electrical connections, stopping the tool. Every time you heat that motor up, even a little, you degrade its varnish; which is the only electrical insulation on its windings. Varnish damage greatly shortens motor life.

Most Industrial grade flex shafts are meant to run at a maximum speed of 15,000 to 23,000RPM. Is it any wonder that running a light duty rotary tool’s flex shaft at 35,000 RPM makes its status “disposable”? Keep your tool at half-speed, and take breaks every few minutes, to prevent overheating either flex-shaft, or the tool’s motor.

    

Do slide accessory shanks all the way into the tool’s spindle; leaving it sticking

partway out is an invitation to a bent shank, which also does the tool no good. That 1/8” shank has to stand up against concentric forces on accessories, which aren’t perfectly balanced, and are revolving at up to 35,000 RPM; this is tough enough if you follow approved procedures; and impossible when you push hour luck.

Bent shanks happen quite suddenly, with cutoff discs and circular saw blades,

because their larger diameters greatly increase concentric forces. As soon as a

shank bends, those forces are multiplied. At this point the collet usually isn’t able to

keep an accessory in the spindle. Consider yourself lucky if you can stop the tool

before a saw blade’s teeth is flung at you at high speed!

Do keep tools dry, whether running or stored. If you only have a two-prong plug (as with most power tools), it is NOT ground fault interrupted, no matter how up to date your house or shop wiring is. Don’t use electrical tools around water; especially not two wire tools.

Keep your tool stored nice and dry; if nothing else, it can be sealed in a Ziploc plastic bag, along with a package of silica gel, when stored in an unheated garage or shed. If you are planning to build heating equipment, water vapor in the air will end up dumped out of the exhaust as super-heated steam, greatly increasing rust and other oxidative processes in your shop. Don’t expose electrical tools to that by being lazy about putting them away properly sealed.

People assume that power tools aren’t exposed to water vapor, because there is no movement in and out of their tool vents, when the tool isn’t running; this is wrong. Temperatures rise and fall every day. Heating air expands, pushing air out of your tool’s air vents. Then, temperatures fall at night, and ambient air contracts, sucking fresh air (with its moisture content) back into the tool. Day after day, fresh moisture is allowed to attack the tool; only a little at a time, but it adds up. Months later you want to use your ‘safely stored’ tool, and it starts right up…or maybe not.

Do clean the motor housing’s exterior after each use. Allowing metal dust to accumulate inside tools can lead to electrical shorts. Blow dust out of air

intakes immediately after creating a cloud of dust from whatever you’re working on; or after cutting, grinding, sanding, or drilling on glass, ceramic, brick, or concrete. You can buy canisters of dry compressed air from office supply outlets. Too expensive? Blow your breath into the tool’s air entrances through a plastic straw.

Be sure to blow away debris from around switches; especially sliding switches. Some tools have stiff plastic sliding levers; at one time they were considered safer; hilarious, right? Debris buildup can jam some sliding switches.

 

Do let any Chinese power tool run for five minutes to seat its carbon  

brushes, right out of the box; most of them come with the brushes already seated, but some do not.

Tighten the plastic covers over the tool’s carbon brushes and their springs  with the flat screwdriver end of the included collet wrench immediately upon receiving

your tool. Check both brush covers before starting the tool, until you’re satisfied

that they aren’t starting to unscrew; if they are, use none-hardening thread-

locker or electrical tape (around the thread) to help secure them in place.

Most new variable chucks need tender loving care; oil them and baby them over

sticking spots, until they wear in a little. Retract the jaws all the way open, and

run a drop of oil as deep into one of the ways as you can. Next, close and open

the jaws fully, three or four times, to lubricate moving parts and leave a rust retarding layer of oil on internal surfaces. Repeat as needed.

Before you get irritated about all the defects you might have to face in today’s imported power tools…if you could jump into a time machine and buy the heavily overpriced tools of the nineteen fifties, you would find them pretty much without defects, but clumsy and heavy. The golden age of tooling never existed. Then as now, we had to take the bad with the good. Objectively, times are never worse or better; just different.

Note: There are more differences in power tools than at first meets the eye. Even models that look exactly alike can have great quality variance; especially with their batteries. I recommend looking at the same tool being offered on Amazon.com, then on eBay, and finally on Temu to find clues about which tool being sold by some faceless drop shipper is a bargain, and which one is an utter dud.

[Mikey98118]

Rotary tools versus miniature angle grinders: Of all the power tools used to build burners and the equipment they heat, your first decision will probably end up being whether you prefer working with rotary tools, or miniature angle grinders. Twelve volt 3” angle grinders are considered the handier choice for cutting on curved sheet metal surfaces, but rotary tools can do very well, with the addition of a side handle and clear plastic safety shield. Rotary tools are considered the right choice for grinding and sanding on burner parts, but a special chuck can be made to mount on miniature grinders, which turn them into handy little angle head rotary tools. Neither rotary tools nor angle grinders constitute a very good choice for drilling in steel, due to their high speeds. So long as you are careful not to buy a lemon, and to also build its accessory, either choice simply boils down to personal preference.

[Hefty]

Mikey, I'm starting to get my head around the changes in pressure and velocity in the mixing tube and nozzle and the effects they have. 

A different question I have but I suspect the answer will relate to the same kind of information: How do you control the shape of the flame without messing up your tuning? I don't want to go as small as a soldering "pen" torch but I'd love to be able to make a similar shape of flame in a small-ish torch, say 3/8"-1/2".

Am I trying to jump to far in one go?

[Mikey98118]

4 hours ago, Hefty said:

Am I trying to jump to far in one go?

The short answer is "nope." With the proviso that your burner design is a strong one to begin with, simply lengthening the mixing tube will lengthen and narrow the burner's flame.

Each burner design reacts differently to input gas pressure, but lowering it will also tend to change flame shape, too.

Now for the long answer. Some designs tend to output longer narrower flames more easily than others do. The best design for doing this trick was the Hybrid burner; they are out of business, and never had any interest in helping people to build their own burners at home, anyway. \

Fortunately, twenty-three years later, I still remember that design. How would you go about building such a burner for say, creating a jewelry torch? By acquiring a spent Co2 cylinder from an air rifle, would be the slick move

If you want to just build a very good jewelry torch, without brazing or welding, I suggest looking at a YBSVO 8mm (0.312”) Sausage Stuffing Tube ($13). This is the smallest stuffing tube size on the market; it is good choice for a 1/8” naturally aspirated burner; it is available on Amazon.com. Input "sausage stuffing tube" and page down. If you decide to go with this path, let me know, 'cuase I just bout one to build such a torch with 

[Mikey98118]

 

So, what to do, if we want to build a proof of concept burner, before spending the time and effort to make a tiny Hybrid burner from steel? Is anything easier to cut and drill then copper plumbing parts? Is super gluing them together just too much work? I would suggest using steel or brass pipe for the mixing tube, though

[Hefty]

Hmmm, I can find the 8mm sausage stuffer tubes on the main amazon site for $12.99 but with $10.64 shipping to Australia (not too bad for international shipping) but the Australian site only has 12mm ones as part of a 3 pc set for $14.99 with $6 shipping. Ebay has the same set for $18 and free shipping. Aliexpress has them for $13.57 (free shipping but probably a few months to get here) but if I go up to 14mm, I've found a 3 pc set (assorted sizes, smallest 14mm) that are trumpet bell shaped funnels and only $4.83

So I might follow your build but reproduce a slightly larger torch? Haven't decided yet.

[Mikey98118]

14mm would be pretty close to equal of the the inside diameter of a 1/2" pipe. A half inch burner is somewhat on the large side for a jewelers torch. What is it you actually want to do with that flame?

[Mikey98118]

Hefty,

If obtaining parts at a reasonable price in Australia is the source of your grief, perhaps a 1/4" Mikey burner is what you need to shoot for.

Look at Trevor's 1/4" Pocket Rocket on page 116 of this thread, and picture it with the length of the mixing tube (the part that extends from the front of the air openings to the end of the tube), increased from nine times the internal diameter of the tube, up to eleven diameters, to create a nice torch flame.

[Hefty]

Knowing what I want to do with the flame is most of my problem!! Yes, I'd like to be able to make a small jewellers torch for finer heating, soft soldering (would a torch like this get hot enough for hard soldering/brazing on small parts?).

 

I have some mild steel tube with an I.D. just over 8mm that I can play with and I've just ordered some 3d printer nozzles in .02mm increments up to 1mm, but yes, getting specific parts cheap here doesn't always work out so the 8mm sausage stuffer may or may not pan out.

I've got access to pretty much everything I need to fabricate a Mikey burner or similar, but as I bemoaned earlier, I'm pretty time-poor so my tinkering comes in fits and starts with lots of time thinking things over in my head or asking questions on here in between.

I think in typing this, I've made up my mind to try  a small Mikey burner and maybe also print an 8mm throat version of AFB's printed burner and I'll compare the burners and also school myself on the effects of different mixing tubes on each of them.

I'm sure I'll have plenty of questions asking the way!

[Hefty]

That should have said "different mixing tube lengths on each of them"

[Another FrankenBurner]

3 hours ago, Hefty said:

8mm throat version of AFB's printed burner

Here was my ¼ inch.

Here was my 1/8 inch.

I have not given them enough time. 

 

[Mikey98118]

6 hours ago, Hefty said:

would a torch like this get hot enough for hard soldering/brazing on small parts?

Yes; that is a very hot flame.

You will find AFB's flame is even hotter. How do I know this? Even if I couldn't see that the flame retention nozzle's incandescence is yellow hot, instead of merely orange hot; the flame itself is light blue. Total combustion within a single flame envelope, is the ideal for compact heat, and light blue is the tint indicating a perfectly neutral flame. As the color darkens it indicates a gradual shift into a lean (oxygen rich) flame, with an inevitable decline in temperature.

Also, I am pretty sure the AFB flame is a lot softer than mine. If you're planning on doing any delicate jewelry work, a soft torch flame is important.

[Hefty]

Thanks to you both for your replies.

AFB, two questions (for now, haha):

1. Are the 1/4" and 1/8" designated measurements just the call-out dimensions of the mix tube pipe or are they accurate throat dimensions?

2. What is the refractory you use for the nozzles. I was considering sifting some of my castable to get the larger bits of aggregate out. Do you think this would hold up?