I’ve searched the archives and found one mention of someone “dialing down” the knob on the regulator to get a smaller output of gas. Can anyone tell me if that is unsafe/dangerous? I’m trying to get a tiny focused flame, and “dialing down” the regulator was the only way to do it. I have no idea what the pressure to the torch is, because, of course, there’s no gauge. (Is there a gauged regulator that will fit a “disposable” canister?)
Anyway, am I doing something unsafe by limiting the flow of propane at the canister?
Can anyone point me to documentation that explains what’s needed, for the present regulator on a 1# canister to operate safely with a torch?
Is your torch just a propane and air torch or a propane and O2 torch? An unregulated valve is basically an on/off valve with no adjustment. If it is just propane and air, you shouldn’t have a problem. If it is propane and O2, especially regulated O2, you have the chance of some sort of flashback if you reduce the propane pressure such that O2 forces it’s way into the propane hose. Do you have smaller sized tips that you can use to get a smaller flame? There is a lot going on here and we need to know more about your current torch. We might also be able to suggest other torch setups that would do a better job of meeting your needs.
Rob, thanks very much for the response. I’m using an Oxygen Concentrator, 5 LPM, no regulator. I’ve been using this with a Smith Little torch, fusing 16-20 ga sterling wire. The tip that gave me the best control was a Smith #6, but I found I had to dial down the propane at the regulator in order not to get a flamethrower style flame when I lit the propane (I’d been using Paige tips for other work, so this was the first I’d used the Smith tips - they’re new and presumably clean). When I reduced the gas using the regulator, I was able to get a small enough propane-only flame (~2" long). Then adding oxygen for a maybe 1/8-3/16" cone gave me approximately what I wanted to fuse the wire.
Looking for a still-more-focused flame, I just got a Swiss Torch with micro tips (Otto Frei had a sale). Again, I found that “down-dialing” the propane regulator gave me better flame control. I have a flashback arrestor at the regulator (though Contenti’s web page for this regulator says that Smith says a flashback arrestor is not needed for this regulator).
Hope that gives you the info you requested; if not, let me know and I’ll try to give you more.
the Smith regulator for the disposable 1lb tanks has a knob that is just “on/ off”, and does not adjust the output.
(I called and asked Smith tech support this question awhile ago…)
red/ green knobs:
I am a bit confused…the Smith little torch has red and green knobs on the handle…the red knob is to adjust the gas/ propane…are you using the red knob to adjust gas flame?
tip size:
Did you get 5 tips with your Smith Torch?
(#3,4,5,6,7…with #7 being the largest)
you are currently using #6…have you tried the smaller tips?…like #4…?
I have a similar setup with both a Little Torch and Meco using Paige tips on both torches and 1 lb. green Coleman propane camp stove cylinders and a 5 lpm O2 concentrator. I can dial the flame down to where, if I am not careful, it isn’t hot enough to solder little 20 gauge posts on to a small 22 gauge 1/4" disc earring. I then have to increase the propane/O2 mix at the torch handle to get enough heat. It is always the knobs at the torch handle that get adjusted to create a flame that will do the job, not at the cylinder. The non-regulated propane valve is wide open and the O2 concentrator is at 5 lpm. While I have them, I never use the single hole tips that came with my torches. I guess that my only suggestion is to work with how you adjust the propane and O2 mix with the valves on your torch handle. I have never used a Swiss torch so I can’t comment on it. My only thought is that the propane regulator may be faulty as I think that it does do some regulation. That would be a question for whomever made the non-adjustable regulator. Good luck and let us know what you find out…Rob
I found the original comment (about ‘dialing back’ the regulator) -
Elsewhere in that thread, he says it acted like a “flamethrower” with the regulator set higher - that’s what I’m experiencing with my Smith preset regulator.
Rob, I’ll try opening it up at the regulator and fine tuning with the torch knob.
Julie, I’m talking about adjusting the flow on the regulator. My regulator doesn’t behave much like an on/off switch. Starting from fully open, it gives me way too much gas (“flamethrower” mode); if I twist toward “off” a couple of twists (not revolutions of the knob, just finger twists), I can get it to drop the pressure to generate a workable flame. I do use the red and green knobs on the Smith Little, but primarily to light the torch or turn it off. If I need a larger flame, of course I open those up and adjust them, but for this project, I need almost the tiniest flame I can get. I tried all the tips that came with my torch (#3-#7); I got nothing with #3 (which I’ve read is expected for propane); and I can’t remember now why I didn’t like #4 or #5, but #6 turned out to be the best for what I was doing.
Smith Little vs Swiss torch: The observed difference: the Smith tips produce a triangular/conical flame, with a wide cone at the base. With the Swiss + micro tips, the inner cone is more cylindrical, around the diameter of the tip. The smallest tip produces a flame with an inner cone that seems as if it can’t be more than 1/64" in diameter. It’s my impression that the narrow inner cone is a key to the improved control I get with the Swiss (I just started using it today, so this is just a first impression).
You may want to reach out to support at MillerWelds.com, who i believe makes Smith torches (?)…
the support representative i spoke to was very kind, informative, and very helpful when i called.
they explained about cylinder volume needed relative to torch head flow rate (or some such…my retention is spotty but it made total sense when we talked…i had gotten a smith versa torch and they were telling me the minimum tank sizes i needed to use…)
I have felt that the change over from my Dad’s Prest-o-lite Plumber’s torch to the Smith Little Torch had a significant learning curve. But once I found the knack of it it has run pretty smooth. I had to remind myself that this was the same principle as with the torches I used in the boatyard when I was working in steel.
My process then as now is open the regulator on the propane wide open, let the O2 flow at 4-5 lpm and fine tune the flame at the torch body. I would bump up the O2 flow depending on the situation. But now I have two torches that I run, one with a melting tip from Paige Tips and the other with various soldering tips. ( I sometimes anneal and solder with the melting tip depending on the material, don’t tell.) I will bump the O2 when when annealing with the melting tip. If it consumes more propane it will need more O2 to support it. Think in terms of the size of the openings the gasses are running through as well as the material you are working with…
And lastly, ever the contrarian, I like to use the single orifice Smith tips for some jobs. They are basically micro brazing tips not unlike the large brass braziers we used in the boatyard. The tips we used to cut steel were more like the multi port tips from Paige, I could braze with a cutting torch tip but not really well.
Having just tried it, you can dial down the pressure on a Smith fixed regulator. Turn the dial to off, then very gradually turn the dial open. It helps a lot to use a candle to light the torch rather than something that sparks.
It is also possible to get very small flames. The flames below are well under a centimeter in length.
The following magnified photo is of a #3 Smith Little Torch tip. You can see that the flame is the same size, or smaller, than the base of the torch tip shaft. This was tricky to light. It needed minimal opening of the fuel dial on the Little Torch, very little O2, and use of the candle flame to adjust things until the flame was stable. A Smith #3 can be difficult to set up.
It’s flame is quite a bit smaller than the Little Torch #3 tip. Again, compare the flame size to the thickness of the torch tip’s shaft.
In addition to using a candle when dialing in difficult to light torch tips, it helps a lot to adjust the oxygen at the concentrator as well as at the torch. I circled in red the steel ball that shows gas flow from the concentrator:
Dial the flow rate down to zero to put the ball at the bottom. Get your fuel lit. Very gently increase the O2 at the concentrator, using the round dial shown at the top in my machine’s case, until all of the yellow flame is gone. Fine tune the fuel and O2 at the torch, but also at the propane tank and at the oxygen concentrator if needed.
Thanks for the Miller contact info. I’ll see what they say. Re how far I’m turning the red torch knob, I’m betting it’s closer to 1/8 turn. I’m looking for a really tiny flame.
Thanks for your insights! I started with a small butane torch and worked my way up to the Smith Little with Paige tips - definite learning curve there. With the current project (tiny pieces, fusing sterling), I ditched the Paige tips for the Smith Little tips - big improvement in terms of getting smaller flames - but the Swiss Torch turned out to be the absolute best. Learning curves everywhere. I’m a happy camper now. Today’s modification: regulator mostly wide open (90%), controlling the propane at the torch. It worked, and answers the biggest concerns of my teacher.
Neil, thanks for this - (including adjusting the propane at the regulator). I’m veyr impressed with those tiny flames. With my Smith Little, I wasn’t able to get anything close to that Impgen flame. I can’t recall why I abandoned the smaller Smith tips, but probably due to lighting difficulty. I’ll try doing what you describe, and see if I can get my torch to hold a flame with the #3 tip.
I had never even considered dialing back the oxygen flow at the concentrator. I’ll play with it and see what happens - so far, I’ve done OK adjusting it ad the torch.
Today, I experimented with opening the propane regulator to just under the “flamethrower” level - maybe 90% open - and using the Swiss Torch knob to control the gas, and it worked fine. (This didn’t work so well with the Smith, don’t know why.)
Thanks again for your thorough descriptions - I’ll treat them as “homework” for tomorrow.
There isn’t much heat in such a small flame, not enough to fuse 16 ga. wire, but if it does what you need it to, great. I don’t use the Little Torch much any more, but the #4 tip was probably the one I used most. That does produce a very long flame.
I prefer a Meco torch now with certain Paige tips and certain ImpGen tips.
i am not familiar with an oxygen concentrator so i am not familiar with lighting torches with them being flowing/ on…with the O2 running from the start(?).
with an O2 tank set-up, the propane is turned in and lit first, and the O2 is introduced after…if the O2 regulator pressure is set too high/ or the tip is small, the O2 can blow out the flame…in which case the O2 regulator pressure needs to be reduced…
the red knob is turned on approx 1/-1/4 turn, and then the torch is lit
sometimes the flame is 4-7” long
…and then the gas flame length is adjusted using the red knob to the desired length…
and then the O2 is introduced with the green knob…it is kind of a back and forth dialing in the red and green knobs, to get the desired inner cone…
the heat is at the tip of the blue inner cone…not so much the yellow outer flame…
does using an O2 concentrator, with it running from the start, affect the torch lighting process?
Using a concentrator is pretty similar, same process, but instead of a regulator, there’s a dial on the machine that controls the LPM output. I leave that set to fully open. The rest of the process is the same as you describe.
