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Thread: Torch Troubles

  1. #1
    Administrator Site Admin Anon's Avatar
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    Torch Troubles

    This isn't exactly about foundry burners, but at least it's about flammable things.

    I have a small, refillable (and also quite expensive) butane torch. I was using it to do a small brazing job (actually the first time I've tried brazing . . .) and it wouldn't burn right. It would sputter increasingly the longer it was on, finally going out about the time my workpiece reached brazing temperature. It also became increasingly hard to relight, requiring matches and eventually burning wads of paper to get it going, instead of its built-in piezo. I finally got the brazing job done, but it took far longer than it should have.

    It seems to be burning with an oxidizing flame (I taped up the air vents and the flame stabilized a bit . . . clearly it gets some of its air from a hidden vent somewhere . . . ), which is another way of saying that it's not getting enough fuel, even with the fuel valve wide open. Could there be a clog somewhere? If so, how do I fix it?

    No, it isn't out of fuel. I refilled it, and that seemed to help for a few seconds, but then it started doing it again.

    This is an intermittent problem . . . it's done this to me before, and after I set it aside for a few months, it started working again. As of now (when I've finished all my brazing, of course) it seems to work fine. Any suggestions as to what's wrong with it, and how to fix it, would be greatly appreciated.
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  2. #2
    I am only familiar with butane cigar and pipe lighters. Sometimes those get air locks. Also, some fuels aren't as clean and can clog up the works. For an air lock... hold the flame valve open, while you are filling it from the fill valve. Sometimes that will help get rid of the lock.

  3. #3
    Sputtering sounds like you're holding it upside-down, letting liquid into the valve.

    I'm not unfamiliar with this, having used handheld propane torches in such orientations, not to mention I once had my 20 pound tank icing up good, so I turned it on its side, letting liquid through the regulator, eventually resulting in sputtering at the monster burner as it spurted liquid! :lol:

    But liquid results in a rich, not lean, flame. Liquid doesn't pull as much air as a gas jet does, and in addition, the liquid has a lot more fuel in it, hence, rich.

    Tim
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  4. #4
    Kinda sounds like a problem with the valve since it is intermittent. A seal getting out of alignment ever so often. Just a guess.
    When you don't have what you need! Improvise.

  5. #5
    Administrator Site Admin Anon's Avatar
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    No, I wasn't holding it upside down--I've done that before, though, and it actually seems to improve the burn, which would go along with my theory that it's too lean.

    I'll try the air lock thing . . . okay, that didn't help.

    The fuel is advertised as "triple-filtered" and "non-clogging," but that doesn't mean it actually is non-clogging.

    If it's a valve problem, how should I fix it?
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  6. #6
    I doubt this one but some butane refills need to be right side up instead of upside down. If you have it bass ackwards it refills with gas instead of liquid.
    Its almost empty.

  7. #7
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    Actually, the way this one is designed (the fill spout is on the bottom) it has to be upside-down for the liquid to fill. That's the position in which the fuel canister is above the torch.

    I finally took the whole thing apart (a drastic measure, as I know how hard these things can be to re-assemble correctly) and after several long, tedious, frustrating, and slightly dangerous hours of fiddling, I found the problem. First of all, the design is terrible. The "variable" fuel switch is really just an on/off valve--sliding it farther does absolutely nothing. This is the first major problem--how am I supposed to adjust the flame for a neutral burn without a variable valve? This would be okay if it burned fine on that single setting . . . but, as luck would have it, it doesn't.

    The second major problem was the fact that the fuel line had no sealant of any kind on one end (it wasn't even a tight fit, and onto a smooth nipple at that), and, as a result, leaked badly. I found this one out the hard way . . . when air intake is restricted and the gas velocity lowered, it burns inside the nozzle instead of the end, igniting this leaking gas, and very nearly taking my hand with it. Luckily, it wasn't such a big leak that I couldn't blow it out.

    The third major problem is that the valve isn't only non-adjustable, the gas pressure on the other end varies widely according to how much liquid butane is in the fuel tank. Since, due to the leak, the torch uses butane several times faster than it should, the level in this tank varies quite dramatically with usage.

    The fourth problem is that there is no way to check the fuel level in the tank without completely disassembling the torch. This makes the other three problems very hard to diagnose.

    The fifth problem was with the piezo unit . . . it had a large and completely useless internal spark gap, enclosed in a plastic tube to keep it from igniting the leaking fuel line. When I re-routed a few wires to bridge this gap, the strength of the sparks increased significantly.

    I sealed up the leaky fuel line, removed the internal spark gap, struggled to get everything back in place, and filled the fuel tank. This time, I got it full--the directions on the torch say to fill for 10 seconds, which is what I'd been doing up to this point . . . I filled for a full minute. And now--you guessed it--it runs rich.

    For a $1.00 Wal-Mart cigar lighter, this level of quality might be reasonable, but for a twenty-buck torch, this is ridiculous. For those of you that might buy torches like this in the future, stay away from the WL Lenk LPT-200 . . . it's complete junk for the price. These torches, in general, are very handy to have, but not when they're this badly built.

    If anybody has any suggestions on homebrew improvements to that valve, let me know . . . it's directly on the fuel tank, though, so modifying it would be a major undertaking.
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  8. #8
    Quote Originally Posted by Anon
    For a $1.00 Wal-Mart cigar lighter, this level of quality might be reasonable, but for a twenty-buck torch, this is ridiculous. For those of you that might buy torches like this in the future, stay away from the WL Lenk LPT-200 . . . it's complete junk for the price. These torches, in general, are very handy to have, but not when they're this badly built.
    A good butane pipe lighter starts at $50... The lighters that sputter out, and die after a few months of cost about $20!! For about $30 you can get a MAPP Oxy Combo torch at some hardware stores. The tanks are the same size as a plumbers propane tank. It can braze weld and cut...

  9. #9
    Administrator Site Admin Anon's Avatar
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    Eh . . . I have a $10 propane torch, that fits normal propane cylinders and works just fine. The problem is, it's a little bit overkill for electrical soldering. Besides, my parents won't let me use it inside.

    I like that little torch, when it works right. The disappointment for me was finding out that the innards were no higher quality, nor better assembled, than the fireplace lighters you can buy for $1.00 each at Wal-Mart. Really, you could narrow the jet a bit, point it down a tube, and you'd have the same thing that I spent twenty bucks on. I was expecting something that didn't leak gas, at least.

    I know about the MAPP gas setup--do you know how long the fuel tanks last? My oxy torch hardly uses any fuel, so I can afford $7.00 a tank for fuel (oxygen is a different matter . . . ), but I suspect this will use a bit more.

    Edit: I was thinking about the MAPP gas torch--not the MAPP/oxy torch, which I already have. I paid closer to $50 for it . . . and oxy is a rip-off, so I was looking for something that heats faster and better than a propane torch, without requiring oxy.

    On a different note, I've been experimenting with quick-heat resistance soldering, like the "Cold Heat" units that sell for an exorbitant price at Radio Shack. So far, all I've managed to do is make a lot of smoke and mess--my transformers are all too small to heat up to soldering temp (half an amp at 9 VDC), and my 6V 5Ah lead-acid is way too powerful. It reaches welding heat almost instantly, albeit over a very small area, and fries my alligator clips (not to mention my fingers . . . ) Obviously, it's impossible to solder like that--the solder overheats too quickly. Besides, it's bad for the battery. A few resistors wouldn't hurt, but I'm going to look around for a better power supply sometime--I don't want to run this off batteries. Does anyone know how "they" manage to keep the AA batteries in the commercial version from dying in about half a minute, while keeping the tip hot? My estimate now is that it will take several amps at 6V, which isn't much soldering time.
    The process of turning stumbling blocks into stepping stones can at times require the use of a large sledgehammer.

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  10. #10
    Those cold heat units are a waste of money. The tips (whatever funky alloy it is) are super brittle, and break easy. (Keep it away from your FETs too!!) For soldering, what wrong with a plain old soldering iron?

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