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Burners 101


Mikey98118

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22 hours ago, rjs said:

concerning 1/4 x 27 tpi taps:

https://www.amazon.com/HSS-Right-Hand-Thread-Tap/dp/B008AT64P8

about $18.50 with the shipping and it says it is high speed steel

Bob

 

I got mine from ebay. Much cheaper http://www.ebay.com/itm/400992184543?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

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1 hour ago, Mberghorn said:

the listing you quoted is for a bottoming tap.  Those things are hard to start without going in first with a tap with a tapered lead in like this one .

http://www.ebay.com/itm/HSS-Right-Hand-Tap-1-4-27UNS-Taps-Threading-1-4-27UNS-High-quality-1pcs/152391238235?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D41375%26meid%3Db18bd6e275114845b583bd79088c8598%26pid%3D100005%26rk%3D2%26rkt%3D6%26mehot%3Dlo%26sd%3D301840549163

Bob  (who, in the past, has been shipped the wrong tap even when he ordered the correct one)

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On ‎3‎/‎3‎/‎2017 at 11:23 AM, rjs said:

the listing you quoted is for a bottoming tap.  Those things are hard to start without going in first with a tap with a tapered lead in like this one .

http://www.ebay.com/itm/HSS-Right-Hand-Tap-1-4-27UNS-Taps-Threading-1-4-27UNS-High-quality-1pcs/152391238235?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D41375%26meid%3Db18bd6e275114845b583bd79088c8598%26pid%3D100005%26rk%3D2%26rkt%3D6%26mehot%3Dlo%26sd%3D301840549163

Bob  (who, in the past, has been shipped the wrong tap even when he ordered the correct one)

I'm not quite sure why it says that because the one that I got is a normal tapered tap. Maybe I fall into that last category of not getting the tap that was ordered, thank goodness there!

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 “F” size drill bits are used for 1/4-27 or 1/4-28 threads, if you tap into stainless steel or have to use a plug tap. If you are threading into mild steel with a starting tap (AKA taper tap) you can use a number 3 drill bit with a few drops of tapping oil (remember to back off the tap about every eighth of a turn to break off the forming burrs). The “F” bit will only produce 50% thread engagement, while the #3 bit will produce 75% thread engagement.

Standard MIG contact tips have 1/4-27 thread. I only recommend starting taps (AKA taper taps) for threading in steel. Even standard 1/4-28 starting taps are often not found at your local hardware stores, which will often try to sell you plug taps instead; but they are easily  obtained online, at reasonable prices. A starting tap for non-standard 1/4-27 will have to be special ordered through an outfit like Tacoma Screw for big bucks, and then you get to wait for however long it takes.

Usually the "wrong" tap will cause a 1/4-27 threaded part to cross-thread when it is screwed into a 1/4-28 threaded hole. But usually both threads are steel. Here, the “screw” in question is a pure copper, soft and highly malleable MIG contact tip that is only one thread pure inch different then the threaded hole it is inserted in. So, rather than cross threading, it changes shape a very small amount needed to conform to the standard thread. I deem it better to take a little extra care the first time it is screwed into place, than to end up with a giant hassle trying to obtain the “right” tap, or ending up with a tenuous amount of thread engaging between MIG tip and gas tube. The choice is yours, but 1/4-28 starting taps have worked quite well for me and tens of thousands of others over the last eighteen years. But, if someone wants to take the other path, I think that's great. Pleas let the rest of us know all about your adventure, afterward :)

 

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I inherited a bunch of my grandfathers tools when he passed and he had a big old school tap and die set, which is way better than the cheapo one that I had, and his set had all the even numbers from 14 all the way up to 28!! Now it has a 27 as well though, lol.

Thanks for the heads up on bit sizes, Mikey! I usually just go down two sizes from the width of the fastener thread.

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I love building small burners out of stainless steel tubing; it makes classy looking tooling, but is unforgiving. It doesn't take more than one time every few years with a nearly completed burner marred with a broken tap embedded in the flame nozzle to sharpen your knowledge about how to treat stainless steel right, 'cause if you do it wrong...it will do you worse!

THREAD/SCREW - Drill & Tap Chart

Machine Screw
Size
Threads
Per Inch
Minor
Dia
Tap Drills Clearance Hole Drills
Alum, Brass,
& Plasitcs

75% Thread

Stainless Steel,
Steels & Iron

50% Thread

All Materials
Close Fit Free Fit
# or Dia Major
Dia
Drill
Size
Decimal
Equiv.
Drill
Size
Decimal
Equiv.
Drill
Size
Decimal
Equiv.
Drill
Size
Decimal
Equiv.
0 .0600 80 .0447 3/64 .0469 55 .0520 52 .0635 50 .0700
1 .0730 64 .0538 53 .0595 1/16 .0625 48 .0760 46 .0810
72 .0560 53 .0595 52 .0635
2 .0860 56 .0641 50 .0700 49 .0730 43 .0890 41 .0960
64 .0668 50 .0700 48 .0760
3 .0990 48 .0734 47 .0785 44 .0860 37 .1040 35 .1100
56 .0771 45 .0820 43 .0890
4 .1120 40 .0813 43 .0890 41 .0960 32 .1160 30 .1285
48 .0864 42 .0935 40 .0980
5 .125 40 .0943 38 .1015 7/64 .1094 30 .1285 29 .1360
44 .0971 37 .1040 35 .1100
6 .138 32 .0997 36 .1065 32 .1160 27 .1440 25 .1495
40 .1073 33 .1130 31 .1200
8 .1640 32 .1257 29 .1360 27 .1440 18 .1695 16 .1770
36 .1299 29 .1360 26 .1470
10 .1900 24 .1389 25 .1495 20 .1610 9 .1960 7 .2010
32 .1517 21 .1590 18 .1695
12 .2160 24 .1649 16 .1770 12 .1890 2 .2210 1 .2280
28 .1722 14 .1820 10 .1935
32 .1777 13 .1850 9 .1960
1/4 .2500 20 .1887 7 .2010 7/32 .2188 F .2570 H .2660
28 .2062 3 .2130 1 .2280
32 .2117 7/32 .2188 1 .2280
5/16 .3125 18 .2443 F .2570 J .2770 P .3230 Q .3320
24 .2614 I .2720 9/32 .2812
32 .2742 9/32 .2812 L .2900
3/8 .3750 16 .2983 5/16 .3125 Q .3320 W .3860 X .3970
24 .3239 Q .3320 S .3480
32 .3367 11/32 .3438 T .3580
7/16 .4375 14 .3499 U .3680 25/64 .3906 29/64 .4531 15/32 .4687
20 .3762 25/64 .3906 13/32 .4062
28 .3937 Y .4040 Z .4130
1/2 .5000 13 .4056 27/64 .4219 29/64 .4531 33/64 .5156 17/32 .5312
20 .4387 29/64 .4531 15/32 .4688
28 .4562 15/32 .4688 15/32 .4688
9/16 .5625 12 .4603 31/64 .4844 33/64 .5156 37/64 .5781 19/32 .5938
18 .4943 33/64 .5156 17/32 .5312
24 .5114 33/64 .5156 17/32 .5312
5/8 .6250 11 .5135 17/32 .5312 9/16 .5625 41/64 .6406 21/32 .6562
18 .5568 37/64 .5781 19/32 .5938
24 .5739 37/64 .5781 19/32 .5938
11/16 .6875 24 .6364 41/64 .6406 21/32 .6562 45/64 .7031 23/32 .6562
3/4 .7500 10 .6273 21/32 .6562 11/16 .6875 49/64 .7656 25/32 .7812
16 .6733 11/16 .6875 45/64 .7031
20 .6887 45/64 .7031 23/32 .7188
13/16 .8125 20 .7512 49/64 .7656 25/32 .7812 53/64 .8281 27/32 .8438
7/8 .8750 9 .7387 49/64 .7656 51/64 .7969 57/64 .8906 29/32 .9062
14 .7874 13/16 .8125 53/64 .8281
20 .8137 53/64 .8281 27/32 .8438
15/16 .9375 20 .8762 57/64 .8906 29/32 .9062 61/64 .9531 31/32 .9688
1 1.000 8 .8466 7/8 .8750 59/64 .9219 1-1/64 1.0156 1-1/32 1.0313
12 .8978 15/16 .9375 61/64 .9531
20 .9387 61/64 .9531 31/32 .9688

Above is far and away the best drill and tap chart I've ever seen; I've been using it exclusively for the last three years.

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Yeah,  I wish I had had that chart back in the middle 1990s,  I still remember destroying a brand new 1/4-28 tap trying to tap a piece of hot rolled steel with a pilot hole diameter of .206 inches.  &   no I do not remember where I got that .206 from  perhaps it was printed on the tap?  The vendor honored the guarantee but he was grumpy about it.   

Regards,

Bob

 

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I bought a 1/4-27 high speed steel tap from eBay last week; it not only was a taper tap (AKA starting tap), bought it has a short section of drill bit on its front end. This is the reason I spend more time researching materials and tools for every new burner design; market forces are always changing the ground rules for what is available and at what prices.

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I found something interesting that I was thinking might work well as a different size of jet orifice, just wanted to get people's oppinions, I'm not sure about the manufacturing tolerances but I'm guessing they are probably pretty good. They are feed nozzles for 3D printers and come in a variety of orifice sizes, here are some that I found. http://m.ebay.com/itm/181817833046?_mwBanner=1

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Maybe yes; maybe no. It is hard to say without knowing anything about their internal shapes. I would be more incline to try them on oil burners, or gasoline burners.

Materials lists for miniature gas tubes and jets for miniature burners

1/8” nipples actually have .405” outside diameters; that starts becoming overlarge for gas pipes as burner sizes drop below 1/2” so smaller MIG tips in smaller gas  tubes becomes the obvious next step to take. Smaller MIG tips with 10-24 thread can fit into actual 1/4” outside diameter tubing with .180” inside diameters. The reduction in tip and tube sizes serve small burners better.

      .250” outside diameter by .180” inside diameter seamless tubing has .035” thick wall that will except 10-24 internal thread, and 1/4-32 outside thread; you can buy it in #316 stainless steel ($2.87 and shipping for one foot length): http://www.onlinemetals.com/merchant.cfm?pid=12938&step=4&showunits=inches&id=902&top_cat=1   

.250” X .180” #304 stainless steel tube $2.41 and shipping for one foot length): http://www.onlinemetals.com/merchant.cfm?pid=12913&step=4&showunits=inches&id=312&top_cat=1   

 

Or you can buy it in DOM mild steel tube ($2.95 and shipping for one foot length): http://www.onlinemetals.com/merchant.cfm?pid=7752&step=4&showunits=inches&id=283&top_cat=197  

 

MK Products 621-0001 series MIG contact tips are used in their Cobra® MX (262, 266), Cobramatic®, Cobra® System III, Cobra® MX Fronius MIG guns; they are 1-1/2” long, including threaded section; they thread into a 12-24 tapped holes. The shorter MK 621-0393 series MIG tips also thread into 10-24 threaded holes for .030” and .035”

http://www.ebay.com/itm/like/322429680280?vectorid=229466&item=322429680280&rmvSB=true

 

Lincoln also makes compatible spray-arc contact tips that are compatiple with MK Products; they are 14” diameter, and use 12-24 thread, are 1-1/2” long including threaded section; and are called PX-621-001 for .035 wires (.044” orifice); PX-621-003 for .045/3/64” wires (.060” orifice); PX-621-076 for .030 wires (.040” orifice); PX-621-0325 for .030 wires (.036” orifice);: http://www.lencocanada.com/files_500-08/500-8.pdf

Lincoln also makes compatible short-arc contact tips in PX-621 ; they use 12-24 thread, are 1-3/4” long including threaded section; and are called PX-621-002 for .035 wires (.044” orifice); PX-621-077 for .030 wires (.040” orifice); PX621-0286 for .045/3/64”  wires (.060” orifice): http://www.lencocanada.com/files_500-08/500-8.pdf

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These materials and tools allow you to create miniature gas tubes and, with the addition of capillary tube in the MIG tips, miniature gas jets. Why should you care? Aside from keeping these parts in keeping with the smaller burners they will power, smaller diameter gas tubes create less turbulence in  the gas stream as it passes into the MIG tip, allowing a shorter gas jet to do the same job as a much longer tube made from a larger pipe.

There isn't enough thickness in the recommended tube to run internal and external thread in the same areas; nor need it. Infernal thread at one end of the tube can hold the small MIG tips, while external thread at the tube's other end can screw into hose barbs or other gas fittings, including a needle valve, to create a smaller version of the standard gas accelerators I've recommended for eighteen years. The external thread can be extended for most of the gas tube;s length, slimply stopping short of the internal thread for the MIG tip to use the Gas tube on a linear burner's reducer fitting.

Finally, for 3/8" and smaller burners a short piece of capillary tube inside one of the longer MIG contact tip (1-1/2"), can when desirable, become both gas jet and gas tube in itself; doing so forces you you to carefully position the air openings, as the accelerator cannot be re positioned to find the sweet spot. For instance, you would do best to use the standard accelerator configuration in a regular 1/4" or 3/8" burner, while you would be better off extending the external thread for linear burners, and use the capillary tube in a long MIG tip when re-fitting an air/propane canister torch into a high power torch/burner. 

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burner(1).jpg

Above is a photo of a canister-mount 3/8" Mikey burner. You can see it is choked back severely; this is because it was just ignited. and was still running cold. Once fully heated the flame nozzle turns orange, and the flame can be turned up more than twice that high. and much faster running. The main point is that this burner, and others, can be canister mounted or mounted on the end of a special extension hose for use in really small forges, as the burner portion is stainless steel, and can be placed inside of a sealed burner portal, to attain very high temperatures.

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The idea of repurposing a plumbers torch this way is very interesting to me. Did you cut of the rest of the original torch tube? Did you use the original orifice as the jet? Or retrofit a capillary tube as described in the previous post? Also it appears that the hole is beveled on the outside, rather than on the inside. If this is true I must have misunderstood your book. I thought the air holes were supposed to be beveled on the inside of the mixing tube (good thing I haven't gotten to that part of my burner build yet).

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The rest of the original torch tube is cut away except for about 1/2" of threaded portion, which is press fit into the the stainless steel mixing tube, so that it can be screwed back onto the bottom portion of the original torch (goose neck, needle valve, etc.). The original gas jet is tossed away. A short bit of .023" I.D. capillary tube is press fit into a MIG contact tip, and the tip is threaded into the end of the goose neck ((old gas tube). The bottoms of the three rectangular air openings are beveled on the outside; the tops the those air openings are beveled on the inside, as per the book.

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One of the things I like about using a canister-mount torch this way is the needle valves on them (I have purchased several of them for study) all have exceptional valve seats, every one of which close completely; this is far from a given with needle valves on pipe fittings these days. Considering that the torch costs less money than the average needle valve, I consider them bargain basement priced parts for re-purposing.

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Please note that the apparently lighter blue of the 3/4" burner in the second and third photos are actually the same tint of blue flame; only it is seen in brighter light. Propylene gas actually makes a lighter blue than propylene flame in the same light; but not much lighter.

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Burners are all about the flame, but...

 

For me, Dragon's Breath describes any kind of exit flame coming out of a forge or casting furnace. However, there can be several different reasons for such flames. When it comes to blue exit flames, they are do to incomplete combustion within the forge, and are full of carbon monoxide; not cool; not acceptable! back in 19999 I started down the long road of burner design because of only a little bit of blue flame coming out of my first forge, which was heated by an old Ron Riel burner.

However, your burner doesn't have to make perfect flames to burn well enough for a properly built forge to finish the combustion of a minor amount of fuel gases. So how do you find good enough? Is there any blue in the exit flame? Then, you need to improve the burner and/or the forge. When that forge runs hot enough there will be no carbon monoxide rich blue flame coming out of its exhaust opening. I have kind of specialized in very hot burners, because they are the easiest way to insure completely clean exhaust; they are far from the only way.

Next comes tuning the burner; once again the hotter the burner the easier it is to tune perfectly. But once again, perfect tuning isn't needed to end up with acceptable performance; its just the most straightforward way.

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@Mikey98118 Would you be able to go into more detail about reducing atmospheres in a forge, such as how it is achieved. I understand that it is beneficial so as to help reduce the amount of scale that builds up but I am unclear as to how to achieve it, or for that matter what it actually means.

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You can produce what is mistakenly considered a neutral flame in your burner, and yet still be producing secondary flames just beyond that so called "neutral" flame. The secondary flame is produced by left over fuel gas from the supposedly neutral flame, which is proved to be somewhere between slightly, up to heavily reducing; how reducing is showed by the amount of secondary flame. But you can build a burner that produces a true neutral flame (that is 100% primary combustion); these have no secondary flame, and therefor produce zero reducing atmosphere. However, that burner will have a variable choke; engaging the choke will again produce secondary flames, and therefore a reducing atmosphere. How reducing depends on how much choke you employ.

So, a little fringe of feather beyond the primary flame is the beginning of a reducing atmosphere; usually able to be burned by a super-heated forge. Continue choking the flame and its atmosphere will become more heavily reducing. Any tinge of green in the flame tells you it is at least moderately  reducing; the more green the more reducing.

Again, we find the goal is to make a good enough burner to burn well enough in your forge, so that you can tune the forge and the burner to produce the conditions you want to work with. How about a burner that will make a "perfect" flame? It can be done, but a perfect flame cannot be maintained in a burner without constant fiddling, because there will be minor fluctuations in the incoming gas supply. You just need a good enough burner, with a good enough tuning job, in a good enough forge, to provide the conditions you need and want at a given time.

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