Burners 101

[Jbradshaw]

A tutorial on making cones would be much appreciated. Now that it's cold out I'm going to be working on burners again. 

This winter the plan is to make a some NARBs. I will be trying it with the already proven Frosty T first. But I also plan on powering one with a Mikey burner. I'm thinking it would allow one to modify the flame from rich to neutral to lean as desired. 

I also want to give a go at a vortex burner this winter. Hence wanting the cone tutorial (though I guess I could just buy funnels). 

[G-son]

Allright, here we go, a basic tutorial about making a cone from sheet metal. 
 

First, we need to know the dimensions. I have selected to make a small cone, 13mm (just over ½") small end diameter, 39mm large end diameter, and 52mm length. 1:3 small to large diameter, and 1:4 small end diameter to length ratio.
(Do keep in mind, it is the inside dimensions you want correct in the end, if you use thicker material you need to compensate by adjusting the diameter you use for calculating. Hade I used 1mm thick sheet metal it would end up 12mm inside diameter and 14mm outside diameter in the small end, for example - i'd have to add 1mm to the diameters to get the right end result.)
 

I simply googled "cone template calculator" and found http://craig-russell.co.uk/demos/cone_calculator/
In the first picture you can see how I have filled in the three measurments, and inside the red circle the calculator shows that the template should have an angle of 87.31 degrees, small radius 26,8mm and large radius 80,4mm.
 

If you're smart you will make a reusable template of paper, stiff cardboard or something like that, and then transfer the outline to metal. In this guide, I'll just scribe the lines straight on the metal. 

Picture two shows the tools and material I'll use, the metal was cut out of an empty shaving foam can just because I had one available. About 0,15mm thick.

Picture three shows the two straight lines scribed at as close to 87,31 degrees angle as I can - or rather, as close to 87 degrees as I can with the junk I've got available here.

Picture four shows the two radius lines scribed using calipers. (If you are making a paper template, there are obviously better tools for drawing circles - but I don't know what they're called in english, and if you have them I probably don't need to tell you how to use them anyway.)

In picture five the cone has been cut out. If you look closely, I have left about 4mm outside the two straight lines. In picture six I bend the excess into flanges that can be soldered/brazed to each other once the cone is completed. With thicker metal I would not make any flanges, instead I would cut the metal along the lines. Thicker metal can be welded/soldered/brazed edge to edge once the cone is completed, very thin metal can not - at least not with common DIY equipment.

In picture seven the cone is carefully bent little by little around a permanent marker. Any sturdy round object with suitable diameter will work - the marker is too thick for the final stages, but worked excellent to begin with. If you use thicker metal you will probably want to use a rubber mallet or something similar to carefully "massage" the metal around a piece of round bar or tubing. Go slow, it is very easy to make sharp bends instead of a continuous round shape. It's better to make 20 passes end to end rolling it a little tighter each time, than to try to get it completely round in the first pass.

In the last pictures you see the finished demonstration cone, ready for silver soldering the flanges - that I won't be doing now, burnt paint smells awful indoors. I just folded a small piece of scrap metal to hold the flanges steady together in the pictures.


There you go, a very basic tutorial about how to make your own sheet metal cones, I hope it all makes sense. Sorry about the picture quality, but I think the idea is clear enough.
There are many diffrent ways to do the metal work, use whatever suits you and your tools best. Once you have the template, the rest is just a matter of cutting and bending metal - and thanks to nerds there are plenty of easy ways to make the template. If you don't want to draw it yourself you can use the software available at https://www.conelayout.com/ to print it ready to use. 

Sorry, the pictures ended up in the wrong order and I'm not allowed to edit it. The last picture should have been first, and the first two last... Oh well. They're there at least.

[Mikey98118]

Thank you for your post. I'm reasonably sure questions will come up about particulars, such as hammer patterns during the shaping of these cones.

I like the flanges, which should be handy for running electrical wiring and gas tubes down.

So what size and kind of linear burner (atmospheric or Vortex) do you wish to build? Remember that Vortex burners can be run in atmospheric mode, or with the supercharger on; either way, it gives an enhaced performance, but with the impeller blades running it can be run a lot harder.

[SLAG]

G-Son,

Thank you for an excellent write up concerning cones.

It IS appreciated.

Could a moderator pin/sticky?, this article on this forum?

Thanks.

SLAG.

this thread has already been pinned

[Frosty]

Practice with construction paper before you try it with metal. It's faster and less work so you don't get as frustrated when it doesn't come out quite right. THEN when you get one that comes out the way you want you have a pattern. 

It's been a long time ago but we made cones when we were making home built rockets in jr. high school. Before the authorities and out parents found out who was launching the things that is.  It's not like we were brewing up large batches of rocket fuel and we never lit a brush fire. I don't recall the name of the teacher who showed us how but it really is as simple as G-Son makes it look.

Nice how to, thanks.

Frosty The Lucky. 

[Mikey98118]

SLAG,

Burners 101 is a permanent thread.

[SLAG]

Mikey,

Copy that.

Thank you for your rapid response.

SLAG.

[G-son]

43 minutes ago, Frosty said:

 

2 hours ago, Mikey98118 said:

Thank you for your post. I'm reasonably sure questions will come up about particulars, such as hammer patterns during the shaping of these cones.

I like the flanges, which should be handy for running electrical wiring and gas tubes down.

So what size and kind of linear burner (atmospheric or Vortex) do you wish to build? Remember that Vortex burners can be run in atmospheric mode, or with the supercharger on; either way, it gives an enhaced performance, but with the impeller blades running it can be run a lot harder.

 

2 hours ago, SLAG said:

G-Son,

Thank you for an excellent write up concerning cones.

It IS appreciated.

 

44 minutes ago, Frosty said:

Practice with construction paper before you try it with metal. It's faster and less work so you don't get as frustrated when it doesn't come out quite right. THEN when you get one that comes out the way you want you have a pattern. 

It's been a long time ago but we made cones when we were making home built rockets in jr. high school. Before the authorities and out parents found out who was launching the things that is.  It's not like we were brewing up large batches of rocket fuel and we never lit a brush fire. I don't recall the name of the teacher who showed us how but it really is as simple as G-Son makes it look.

Nice how to, thanks.

Frosty The Lucky. 

 

Mikey:
I'd love to give advice on things like hammer patterns, but I can't say I know enough to help someone with that. I started out cutting out a piece of metal, grabbing a mallet (or hammer, tried those too but they tend to dent the metal instead of bending it), and holding the metal over any rounded metal object in sight trying to figure out how to get that mallet make that metal thickness move the way I'd like it to. It's more a matter of getting a feel for how the material and tools work than an exact science, so the best thing to do is to simply give it a try.

Being my first burner build, I am thinking "keep it simple, stupid" is the best foundation to stand on. A vortex burner may be a good project later, but for now I think atmospheric is the best way to go. Crawl first, run later! 
For size, I'll build it around a "0.6mm" MIG tip, so if I'm not mistaking that'll make the mixing tube ½", or close to that. (I can roll a short tube out of sheet metal too, so it might be easier for me to alter mixing tube size to fit the gas jet, than change gas jet size to fit the rest of the burner - as long as a slightly uneven tube isn't a disaster.)


SLAG:
You are very welcome! Always nice to know that work gets apprechiated! (That goes to all of you.)


Frosty:
Did you make nose cones (that finish into a point), or cones with both ends open like this one? The open ended ones are fairly easy to work with (as long as the metal isn't too thick or "springy"), while a cone that goes all the way to a point can be difficult - the closer you get to the tip, the tighter the metal has to bend, and the harder it is to hold something inside as an anvil to hammer it against. But absolutely, it's much easier to make them in paper first so you can see what you're going to get. Making prototypes can save alot of time sometimes!

[Frosty]

The rockets we were making were in several sections: cylindrical body, truncated cone tail section and a nose cone on another truncated cone for the forward section. We needed a way to deploy the parachute and over powered like teenagers make things we couldn't let the deploying charge pop the top half off or the rockets came apart completely.

We weren't building rockets out of metal, even in the '60s that was a federal crime. We made them from construction paper impregnated with polyester resin. Not that we didn't prototype rockets from metal, we just never put an engine in one. Our parents would've killed us.

Dad was a metal spinner and machinist and I grew up in his shop so I had access to tools and equipment no school shop would allow on the grounds. Figuring out how to make round hollow forms was my meat and drink till Dad got successful enough to hire too many guys and OSHA booted me out of the shop. 

One of these days I'm going to set up my lathe in the shop and show you guys what a proper naturally aspirated burner looks and performs like. Linear or jet ejector.  Yeah, like I'll ever get to it. I'm a TBI survivor and the tree took me out of the game before I got the shop finished so my lathe is still stored in the Connex. <sigh>

To be honest I don't know if I COULD spin safely, even within the definition of safe(?) metal spinning.

Frosty The Lucky. 

[Mikey98118]

On 12/15/2017 at 4:45 PM, G-son said:

Being my first burner build, I am thinking "keep it simple, stupid" is the best foundation to stand on. A vortex burner may be a good project later, but for now I think atmospheric is the best way to go. Crawl first, run later! 
For size, I'll build it around a "0.6mm" MIG tip, so if I'm not mistaking that'll make the mixing tube ½", or close to that. (I can roll a short tube out of sheet metal too, so it might be easier for me to alter mixing tube size to fit the gas jet, than change gas jet size to fit the rest of the burner - as long as a slightly uneven tube isn't a disaster.)

Okay, here's my first suggestion.; look up a schedule #40 pipe chart, to see what nominal inside diameter a 1/2" pipe has and add an additional 1/8" diameter to it. Then use tubing, which comes in a whole lot more sizes than pipe, to get the desired diameter or as close to it as is convenient; this is a lot easier than using capillary tube to match up the MIG tip better to 1/2" pipe. 

[Mikey98118]

Yes, a regular .6 millimeter contact tip will work but is just a hair large to work at the maximum advantage in a 1/2" pipe burner.

[G-son]

Right, actual diameter of pipe isn't as "advertised". If I found the right pipe chart actual ID of sch40 ½" pipe is 0,62", about 15,75mm. Adding 1/8" (3,2mm) to that we end up just under 19mm. I don't think I have 19mm in the garage, but both 18mm and 20mm should be available. I'll try those first, since I already have them and they're pretty close to your recommendation.

When pipe diameter has been used to determine other dimensions (such as mixing tube length 9 times the diameter), is that based on nominal diameter or actual diameter? Since a ½" pipe is actually 0,62", that's a 24% diffrence, quite alot. 

[Mikey98118]

7 hours ago, G-son said:

When pipe diameter has been used to determine other dimensions (such as mixing tube length 9 times the diameter), is that based on nominal diameter or actual diameter? Since a ½" pipe is actually 0,62", that's a 24% diffrence, quite alot. 

I use actual inside diameter times nine, starting from where the flare of the air inlet or forward ends of side air opening's forward end or ends stop and the mixing tube area begins.

The nine diameters rule of thumb should be regarded as a general reference point for burners, as it is changeable not only according to mixture flow dynamics, in accordance to burner design, but also by preferred desired flame dynamics. I have chosen as much as ten diameters in burners meant primarily for hand torches and as few as eight diameters in burners meant to output the shortest flames possible in a stable Mikey burner, while eight diameters are Frosty's recommendation for his "T" burners.

[Mikey98118]

More on flame stability

Hard flames, (AKA High-speed) have a greater tendency than softer flames to become unstable; how much stability is needed is an individual choice. I have not found a problem in most people in  judge wisely on this issue. However, one thing that is true with most burners is that burners small than 1/2" are easiest to tune for hard flames and easier to tune into instability. Fortunately, unstable flames become more stable on burner installed in equipment. 
 

[Mikey98118]

Flames with added oxygen, full or partial, can be laminar or turbulent, and still be very hot. But air-fuel burners are nearly all either turbulent or weak. I have only seen one burner with a very hot laminar flame, and that was a "T" with a flame nozzle.

[ede]

[Mikey98118]

Yes, EDE, that is a perfect hard flame on what I'll assume is a 3/8" Mikey burner...BUT we need to discuss how you choose to build it. Did you decide to use the narrower air openings, which I felt would increase swirl, leading to increased flame sizes? Does it produce a stable flame over a  longer pressure range? I am pleased to see you stuck with all stainless steel construction, which costs so little additional money in small burner sizes.

Glad to see you back, and how the heck have you been?
 

[ede]

Hey Mikey, glad to be back thank-you.  Been doing well, forging lots of tools lately.

As far as the build, this is actually a 3/4” stainless Mikey burner with 7 slots.   Using a .023 tip after switching from the .030 has made all the difference in performance.   Some forge author  suggested switching tip sizes,  i was a little cynical but he was right.   I’m getting nice long heats on 2” stock and Yes, very stable flame at all pressures.   

Glad to see your continued posts and helping out fellow smiths.     

[Mikey98118]

MIG contact tips come in very limited sizes since they are only designed to run welding wire through. The next best plan is to drill into half-hard brass, creating your own gas jet. Most people aren't set up to accurately drill miniature holes, and so I suggest capillary tube to get around their limitations. Whichever way people go has its own problems.

In MIG tip tables I recommend both .023" and 030" contact tips on my 3/4" burners since one is a little undersized and the other is a little oversized. But one will always turn out best on any given burner because none of them are exactly the same.

[BIGGUNDOCTOR]

What about using carburetor jets? 

[Charles R. Stevens]

BG I would think the same issue as with comertial gas’s jets. Ease of sourcing them. Secondly most automotive, motorcycle and small engine jets are acualy a needle and set assembly

[Hans Richter]

Hi gents, discovered this little guy between my belongings -a classic Bunsen burner and decide to reactivate him to melt wax for the casting activity’s, kiln ingots before entering the crucible and so on.

Till now using the kitchen stove (despite of the ‘landlord’) or ordinary weed burners (you know). Nice clean and hot flame. Do you use Bunsen or familiar burners to, and for what purpose?

Cheers, Hans

[ThomasPowers]

Drawing temper on items.  Warming cold items for gluing/epoxy.  Boiling the tea kettle out in the shop...

[G-son]

20 hours ago, BIGGUNDOCTOR said:

What about using carburetor jets? 

This is a box of main jets for small Dellorto carburetors, used on mopeds and other small twostroke engines. They are easily available, often in sets of ten, and the size is (unlike many other jets) graduated in hundreds of a millimeter, i.e. 68 means the jet has a 0,68mm hole. The step between jet sizes is about 0,025mm, so the series usually goes 60, 62, 65, 68, 70, 72, 75 and so on (I'm suspecting that the actual hole sizes may be in even 0,025mm steps all the way, but the stamped numbers are rounded to even numbers).
Thread size is M6x0,75 for the ones in the picture, Dellorto also uses M5x0,75. There are many other types of jets around for carburetors, the hard part might be getting a tap for the correct thread or jets that fit a standard thread.

These jets are not designet to produce a straight jet of fuel (or gas, or anything else), it is just supposed to be a flow restriction of very precise size. I am not sure if the relatively short hole with a sharp step at the beginning works well as a gas jet for a burner.

Coming to think of it, I do have a couple of scrap (a.k.a. spare part) carburetors somewhere, maybe I should take the part that the jet screws into from one of them, and try building a burner around that. 

[Mikey98118]

Since the smaller the burner size the shorter the gas jet needed, some of the smaller jets would probably work out okay. Furthermore, being a threaded brass part, they should work out well as a base for holding capillary tubing for longer gas jets onto...