Jump to content
I Forge Iron

Burners 101


Mikey98118

Recommended Posts

"Just a little off" can be handy

Millimeter, is something I've considered as a dirty word since teachers started pushing it back in high school. Millimeter tubing is always a little different than what I'm looking for, and millimeter drill bits are too...

Except that sometimes, those slightly different sizes become handy gas orifice diameters, and sometimes that little difference in drill sizes are just what you need to make a better match up with fractional tubing.

Link to comment
Share on other sites

  • Replies 3.6k
  • Created
  • Last Reply

Top Posters In This Topic

Three pieces of 4mm I.D. by 7mm O.D. by 300mm (11-13/16”) long seamless brass tube, with 1.5mm (0.058”) Wall Thickness are available from Amazon.com for $16.89. 4mm is 0.15748”. 1/4-27 thread for MIG contact tips have a minor diameter of 0.205” so this tube can be threaded for MIG tips at one end. 7mm is 0.275”; thus, accepting various 1/4” dies (fine thread is better than coarse thread for this). By stopping the outer thread short of the last 3/4” of length, you can use this heavy wall tubing is excellent for creating smaller versions of lamp thread gas assemblies. This tube can be interference fit into standard lamp thread; or slid more easily into it, if it is sanded just a little to smooth out its interior. The tube also fits fender washers, and other flat washers, for use in smaller burners as the only gas tube.

Link to comment
Share on other sites

Flat washer gas assembly mounting

 

It is necessary for incoming air to sufficiently mix with fuel gas. A swirling motion delivers the most mixing for the least drag on air flow. Pipe reducer fittings and other funnel shapes provide convenient ready-made forms for this purpose.

    It has been well established that the gas pipe and whatever MIG contact tip, etc. is used for a gas orifice should be axially centered in the reducer's large opening by, whatever means is convenient. BUT the devil is in the details, because how you choose to mount the gas assembly, is your first and best chance, to gain that something extra that we all want to see in the flame; don't waste it!

    Why such emphases on a “minor” detail? You have an energy budget; it's limited to the air induction that your gas orifice supplies to the gas stream, which is the burner's air induction engine. It takes energy to get air moving, and also takes energy to change air direction. So. starting air swirl at the same point where motion begins, will require the least energy from your tiny store.

    So why not install a high-power fan or compressor at the opening? How much breath is required to blow out a candle? That is about the maximum power input--at the wrong place--it takes to blow out a burner flame too. You want burner magic? It comes from control.

    Another important factor to consider; as with a whirl pool, nearly all of the incoming air will enter near the opening’s periphery. No significant air will move down the center of the opening, So what? So, this tells you where streamlining matters, and where it doesn’t.

    Mounting a gas assembly has two facets; what is easy versus what works best. There can be no "perfect answer because, aside from tooling and skill levels, we all have preferences; mine is maximum control of the parts being assmbled. You get the best results for the least work, if Murphy is never given a chance to muck things up.

    For burners needing a flat disc of up to 2-1/2” diameter or less, fender washers can be purchased, keeping your work at a minimum, by using only part of the instructions below. For larger openings than 2-1/2” you must completely fabricate your own part.

    So, why start with sheet metal, or a fender washer anyway? Because you begin with a flat surface; all you need do, is avoid kinking it, to ensure that your gas assembly will remain axially true. Use a divider (best) or compass (workable), and a prick punch, to lay out a disc of the same diameter as the outer edge of the large opening in your reducer or funnel. whether you want to silver braze, solder, screw, or glue the disc in position.

Cut a hole in the middle of the disc for your threaded gas tube to slide through. Mark out three roughly equal spaces for ribs between the air openings. Use the divider or compass to mark three equal spaces for the ribs. Drill 1/4" or smaller holes between the areas of the ribs and well outside the area of the nut over the center hole. Remember that there is no significant air flow in the central part of the disc openings, so don't shortchange yourself on material in this area.

    The ribs would be fairly narrow if you kept their lines parallel, but that isn't desirable. You want them to become wider as they extend toward the periphery of your disc. You will also cut a groove in their bottom face, and bend one side downward at a forty-five-degree angle; this will help encourage swirl in the incoming air, while helping to keep the structure rigid. You must cut the sections that angle downward small enough to fit inside the opening, leaving the rest of the rib still long enough to sit on the outside of the reducer or funnel. Why would you bother? To ensure that the gas tube’s mounting is diagonal with the air entrance; thus, helping to ensure that the gas assembly will remain axially true to the burner.

    The gas tube has an exterior thread, that allows it to run back and forth in a nut, or a 1/2'” long brass 1/8 IP for lamp fixture (to solder or silver braze on the mounting plate), for fine tuning burner performance.

    For people who can’t find or afford “doing things the right way,” or find all these parts and tools, there are brass pipe, steel tube, etc. that can be slid into the lamp thread from your hardware store, where it can be trapped in place with silver braze, solder, or even resin; it’s the lamp thread that has to move back and forth, for proper tuning. A nut snugged up on either face of the hole in the mounting plate can keep everything tight, so that tricky solder or brazing work, is only desirable; not essential.

    You also don’t need to perfectly match up the inside of whatever you use for a gas pipe with the inside of the lamp part. Adding inner and/ or outer spacers are just fine so long as you solder, braze, or, glue them, to prevent movement between your parts. Inner spacers don’t even need to be gas tight; just the ends of the gas tube need that. Inner spacers are just there to improve flow. Even electrical tape can be used to provide an interference fit between the gas pipe and lamp thread.

    Gluing gas assembly parts? Anyone who has played around with air-fuel torch parts will have noticed that a few of them are glued together (mostly on old equipment) with some kind of black resinous substance. And anyone who has rebuilt an engine knows that gasket sealant is black and quite tough. Two and two makes…

    Thread sealant comes in hardening and non-hardening types; both kinds are resistant to vibration, and, like gasket sealant, thread sealant for fuel lines, are rated for use with petroleum products. LPG stands for liquid petroleum gas; that includes propane, butane, methane, and propylene fuels. 

 

Link to comment
Share on other sites

MIG contact tips serve very well as gas orifices for high-speed burners down to ¾”. With the addition of capillary tubes, MIG tips continue to work well for ½” and 3/8” burner sizes. But 1/4” burners and all smaller burner sizes burn best with 3D printer nozzles, because they come with orifice diameters down to .2 millimeters (0.008”). Printer nozzles have millimeter threads, which work out conveniently with brass millimeter tubing. This is especially convenient, since small brass tubing, both thick and thin wall, are easiest to find in millimeter sizes.  

Link to comment
Share on other sites

MK8 extruder nozzles are interchangeable with Makerbot, Reprap Prusa 13, Ender 3, Ender 3Pro, and CR-10 nozzles; they are available in: 0.2mm (0.008”): 0.3mm (0.012”); 0.4mm (0.016”); 0.5mm (0.020”); 0.6mm (0.024”); 0.8mm (0.031”); and 1.0mm (0.0039”). The thread M6. The hexagon head takes a 6 mm wrench.

Link to comment
Share on other sites

MK8 extruder nozzles are interchangeable with Makerbot, Reprap Prusa 13, Ender 3, Ender 3Pro, and CR-10 nozzles; they are available in: 0.1mm (0.004”):  0.2mm (0.008”): 0.3mm (0.012”); 0.4mm (0.016”); 0.5mm (0.020”); 0.6mm (0.024”); 0.8mm (0.031”); and 1.0mm (0.0039”). ”). The nozzle’s hexagon head takes a 6 mm wrench; its M6 thread has a maximum diameter 0.0231” should screw nicely into a 7mm O.D. to 4mm I.D. brass tube (use a 5mm drill bit). With sufficient wall material left not to be too weak. But ¼” tube is probably not going to work out.

 

I have the brass millimeter tube, and am waiting for millimeter drill bits and taps to arrive, to find out if all this works as planned.

 

Link to comment
Share on other sites

I was going to suggest jewels for watchmaking may have the potential to be gas orifices, you know those synthetic rubies that are the bearing surfaces for pivots.  They ain't cheap though and heaven forbid you loose it!  I was thinking they could be flush or gypsy set by a jeweler.  The extruder nozzles sound a lot more straight forward to use if you can get em to work.  

Screen Shot 2020-12-29 at 9.01.04 PM.png

Link to comment
Share on other sites

Ede:  Good Idea but only if the hole goes all the way through.  I know that in my old pocket watches the hole where the axle of the gear goes in the jewel is not pierced all the way through.  I wouldn't want to think about how to drill it completely through if it wasn't already.  These days they are usually some sort of synthetically grown corundum.

"By hammer and hand all arts do stand."

Link to comment
Share on other sites

Good to see you back, thinking and posting here, EDE.

Actually, others came up with this wrinkle, and I think at least one of them, Another Frankenburner, has already started using printer nozzles. I started reading about them on his thread, which has since disappeared. What first brought them to importance for me is, that like MIG contact tips, they are low cost, easily available, and screw mounted. Unlike my favorite gas orifices, they have very short drilled holes at the end of streamlined interiors; a negative factor in larger gas orifices, but a big plus factor in tiny orifices, due to the tremendous increase in friction created in capillary tubes as their sizes decrease, Also, propane is far from a clean fuel, and will clog small tubular gas orifices all too handily.

Link to comment
Share on other sites

Frankenburner wrote: "This burner turned into a whole different dragon."

Yes; that is both the upside and the downside for me :rolleyes:

On the one hand, I expect they will increase the turn-down range in mini burner sizes. On the other hand, I will be starting back at first base; it's a whole new ballgame.

Link to comment
Share on other sites

Magic&Shell 2-Pack 7mm Hex Brass Shaft Couplings are a convenient choice for silver brazing a gas tube holder at right angles on a fender washer, but the small hole in the end of the coupling must be drilled out to 7mm to allow 7mm by 4mm heavy  wall brass tubing to pass through. You will also want to barely sand the tubing, or the inside if connector, to create a perfect fit. Place the tiny set screws on the short end of the hex wrench, and sand off their sharp ends on #400 grit sandpaper, to keep them from scarring up the gas tube; sets of two are available through Amazon.com for $7.

Link to comment
Share on other sites

Grit burrs (AKA stones) versus grit wheels

Rotary burrs have advantages when working inside small tubes and pipes. Wheels grind faster than burrs, because of their larger diameters, if the pipe or tube is large enough for their use. Both burrs and wheels are available in aluminum oxide, and in silicon carbide (which makes harder and sharper grit). But, silicon carbide burrs are much more expensive than the wheels. All of these products consist of grit held together by resin. But burrs are also glued onto steel shanks. Wheels have arbor holes that accept rotary mandrels, so wheels are less expensive, and more durable than burrs. Silicon carbide burrs and stones usually come in blue or green colors.

Link to comment
Share on other sites

 Sorting out the lemons

Rotary tools can replace a variety of other equipment for small-scale tasks; cost once restricted their use to professionals, but their expense has been declining for over two decades, along with that of their accessories. During that period, equipment choices have flourished, while steel cutting accessories and techniques have been improved; providing wonderful control for building a small burner, and the equipment it heats. Rotary tools can easily have attachments added (ex. clear safety guards) to enhance their effectiveness.

    Electric die grinders have been getting more compact over the same period, and have now become attractive to home hobbyists, and tradesmen.

    Now for the bad news; it’s the wild west out there. Nearly all of this equipment is imported from countries like China, and India; but prices don’t necessarily reflect their low manufacturing costs; while these are generally reasonable, you will find some marketers asking much more than the rest of the pack; it just shows the seller’s contempt for your intelligence.

    A favorite “bait and switch” tactic is a seller with the lowest initial price, followed with ridiculous ‘shipping fees’; the latest version of this scam is all of the prices, including shipping fees more than doubling, while you are in the process of ordering your ‘bargain’ tool. If you’re not paying attention, you get stung.

    Most people just get bilked with shoddy goods and service; there is a whole ‘industry’ that has grown up around drop shipping worthless junk; before purchasing online, look at customer evaluations of the item, and the seller, on Amazon.com; not on a net ad. Grifters are trying every trick they can think of to get around this system.

    Where do you think look- alike super cheap tools come from? Foreign factories have quality control too, but their rejected parts are more likely to be sold to another OEM, than scrapped.

    BUT, consider whether or not most of those bad reviews are legitimate, or just showing the complainer’s ignorance. Most of the larger mandrels I recommend for this work, are constantly dinged as “poor quality” buy users who failed to insert the mandrel’s shank completely into the tool’s spindle; you can tell this because their photos show mandrels bent somewhere toward the middle of their shanks, rather than just below their heads; demonstrating what they did wrong, and also that they still haven’t bothered to read a rotary tool instruction manual. Repeat complaints fall into two categories: real problems, and user ignorance. How do you tell them apart, considering that the tool is likely new to you? Look up a similar product that is known for its high quality, and read the complaints listed about it. The remarks that match, can reasonably be put down as user ignorance; the ones that don’t should be taken seriously. Then, there are obvious flaws. If you see owner after owner complaining that the tool just fell apart and/or quit working “right out of the box,” it would be silly to assume that all those people were just too stupid to use the tool properly.

    Between fly by night drop shippers and recognized tool lines, are importers who have developed their own product lines over several years; what difference is there between them and the overwhelming majority of yesterday’s brand name tools? Not much, since both types of company are essentially just sales outfits these days, with fairly weak motivations for ensuring customer satisfaction; they are better than fly by night drop shippers, but that is a very low bar.

    However, the one who needs watching most, is you. Tools “are what they are”; not what you wish they were, or what you think they should be. When you go shopping, leave all of your hopes and dreams behind. Go beyond practical, to outright cold-blooded.

    When it comes to buying power tools, remember that old street adage; “nothin’s fer nothin.” On the other hand, you will find a frequent refrain in bad product reviews; “you get what you pay for.” Not necessarily. There is no simple formula for ending up with a good tool. Either you will do some research before buying, or just roll the dice and hope. “Made in America” is the past. Your new standard should be “made with reasonable care, and backed by more than happy talk.”

    Skip right past all those joyful four- and five-star reviews, which mostly boil down to “A sparkly! I’ve always wanted a sparkly of my very own.” Go straight to the one- and two-star sections; both of them will bring up the same problems, but the two-star section tends to have more clear minded comments, while the one-star section has more rage. Consider what percentage they amount to, together. Finally, look at the three-star section to see how many of those reviews belong in the two-star section. 

    Are those reviews way out of date, or are there plenty of recent reviews that say the same thing? Some products do get improved; rarely, but it does happen. On the other hand, some sellers have begun blocking you from reading their one- and two-star reviews. When you see that, just move on, because anything more that you learn, is only going to be bad news.

    When you see complaints about obviously used tools sold as new, it indicates that the seller is willing to fob off lemons to people, rather than accepting responsibility for them. If you buy into his jolly advertisements, instead of the bad reviews, you’ll richly deserve all you’re going to get.

    When you see rotary tools sold with their own case, filled with accessories, and a flexible drive thrown in, you are supposed to jump at the chance of something extra for free. What you you’ll get is a pile of junk for more than a high-quality rotary tool would have cost. Wishful thinking is willful stupidity.

    Another indication that the tool is junk-for-sale is awkward brush cap protrusions and/or no care taken to position air entrances were your hands won’t smother them. Plenty of junk tools don’t have these flaws. But no care taken about such obvious defects, should alert you that more important matters, won’t be seen to either.

Link to comment
Share on other sites

Getting things straight :)

7mm by 4mm seamless brass tube can be interference fit into standard lamp thread; or slid easily into it, if the lamp thread is sanded just a little to smooth out its interior. it also fits micro-motor couplings, for use in smaller burners as the gas tube.

    Drilling and tapping thread for MIG tips, or 3D printer nozzles into this tube requires a drilling press and vice, or else some kind of temporary fixture to help guide the drill bit, keeping it axially true enough for this process to work properly. Fortunately, lamp thread, from the lamp section of a large hardware store, will do nicely as your guide. Use it when drilling the hole for the tap, and again to guide the tap true, during threading.

Link to comment
Share on other sites

Back to the why of things

So, the why of things seem to have been forgotten in the details of how. The minimal diameter of these brass gas tubes continue to be important for good flow into the gas orifice, whether that is a short length of capillary tube trapped in a MIG contact tip, or a tiny 3D printer nozzle.

Threading the gas orifice into the end of the gas tube continues to be important so that they remain easy to clean. Propane is not a very clean fuel source. Small burners need ever smaller gas orifices. The orifice on a 1/4" burner WILL become plugged with tar and wax from the fuel. A friend of mine, how always bought the cheapest propane he could find, had his burner plugged completely closed in three weeks. I had to drive to his place and prove to him what the problem was, because he couldn't believe it was possible. After unscrewing the MIG contact tip, and using torch tip cleaners to pop out the black little sphere of tar, any thought of making gas orifices the easy way ended permanently; that orifice was thirty-one thousandths of an inch. The orifice size on a 1/4" burner has one-fourth that area!

Link to comment
Share on other sites

 

    You don’t need oil when drilling brass tube, but don’t expect it to drill faster than mild steel.

    Start threading with your tap as close to axially parallel as possible, and only turn the tap until you can feel resistance suddenly increase (the “quarter- turn and reverse tool to break burr” rule of thumb isn’t adequate for hard brass and 75% thread engagement; instead, you must back off the tap off as soon as you feel a sudden increase in resistance to movement. It doesn’t matter how little progress you make before breaking the burr away from the thread end, and starting another twist; have the patience to follow this advice. You are going to be using small (and therefore easily broken) taps. Chase the forming thread frequently, to keep it forming smooth.

    Be liberal with your tapping oil, and back the tap out completely (in order to clean out collected metal chips) every full turn; a broken tap can only be removed if there is enough of it left to unscrew it from the part using pliers or vice grips.

    There are three kinds of thread taps: "Bottoming," "plug," and "starting” (AKA “tapered”) It should be obvious that stubbornly insisting on a starting tap (even if you have to special order it), will return big dividends once you start threading this tube. Learn the difference between starting and plug taps, so as to defend yourself against ignorant or lazy sales clerks. It is better to pay a premium price and/or wait for a special order starting tap than to try forcing a plug tap to work in a critical part.

    MIG contact tips have much longer threads than 3D printer nozzles, and MIG tips are soft copper, which is easily bent into perfect alignment with the gas tube. 3D printer nozzles are hard brass, with short threads. There is more than enough slop between the nozzle and gas tube threads to allow the nozzle to be set out of axial alignment. If this happens, ink mark the area on the gas tube that needs sanding, and use #400 grit sand paper to adjust the nozzle into true alignment.

   

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...