[TheForge] Oxy/Propane reprise

Mon Nov 9 21:13:37 EST 2009

Ron:
Frosty would probably chime in that you'd seen an Allstates propane 
torch torch, which he loves, apparently for good reason.
All cutting modern cutting torches have a venturi assisted oxy jet i 
read somewhere.

Ron Lass wrote:
> Hey guys,  I remember attending a demo of a propane cutting torch at a local welding supply party.  This thing, (I can't remember the name) but it worked on a venturi principle for the propane,  you just adjusted the O2 and the propane followed.  I tried it and it worked great on a 1" piece of steel.  Next, my wife was convinced to try it, (never cut anything except with a knife or scissors) and she did a perfect job.  I think the secret may be in the venturi type setup.
> 
> Ron Lass
> 
> 
> 
>> Date: Mon, 9 Nov 2009 15:35:59 -0600
>> From: crosspein at sbcglobal.net
>> To: theforge at mailman.qth.net
>> Subject: Re: [TheForge] Oxy/Propane reprise
>>
>> Since I already had the torch angle at a "push" angle of about 20 
>> degrees, I'm going to assume that torch was too far away, and probably 
>> in need of adjustment.
>>
>> I had read on some mailing list somewhere (while trying to get as much 
>> info on this as I could find) that the secondary flame envelope on 
>> oxy/propane was hotter than the primary, so keeping the torch further 
>> away (up to a point) was better than up close. I guess that's what I get 
>> for trusting internet wisdom :-)
>>
>> Too bad I have class tonight. I'd love to play with this when I get 
>> home. But we're TIG'ing Al, and I find that great fun too, but I'll be 
>> glad when the semester is over. I didn't get into the next session 
>> (filled), and I'm not spending enough time with my hammer.
>>
>> **Paul
>>
>> Peter Fels & Phoebe Palmer wrote:
>>> Paul:
>>> That travel speed was much slower than it should be. Try tilting the tip 
>>> in the direction of travel once the cut is started.
>>> Adjust the torch when the oxy lever is depressed. There should be little 
>>> or no feather. Crank the preheats up so you can proceed faster..go as 
>>> fast as possible without losing the cut.  pf
>>>
>>> Paul N wrote:
>>>> Thanks Ben,
>>>> There's no question that the wind was a factor, as the torch blew out a 
>>>> few times with a gust of wind. I'm still a little unsure of how my flame 
>>>> profile should look. I was setting the mixture so there was little of 
>>>> what I would call an "acetylene feather" of I were using acetylene. But 
>>>> those cones in the preheat flame were mighty small, maybe 1/8" to 3/16".
>>>>
>>>> I was successful in cutting my circle, I just had some difficulty a few 
>>>> times. Actually, now that I gave it some thought, that I did cut about a 
>>>> 90" long kerf, and while I don't know how fast I was moving, if it were 
>>>> about 3 inches per minute, that's still about 30 minutes of continuous 
>>>> cutting. And there were segments where I was actually moving along 
>>>> pretty well for an inch or two before I got a little ahead of my heat 
>>>> and had to pause.
>>>>
>>>> And I know I was going pretty slowly, particularly when I got "near the 
>>>> end" and was worried that the change in balance was going to make the 
>>>> thing move alot, so I was a little more outstretched, and consequently 
>>>> less steady with the torch. (As it turned out, the work was sufficiently 
>>>> secure, and as the cut completed, it didn't move much)
>>>>
>>>> It'll be a good week before I get a chance to try again. Gotta devote my 
>>>> saturday this week to the UMBA fall meeting. At least I have a more 
>>>> manageable piece to practice on now. A 4'x4'x3/8" piece is not that easy 
>>>> to move around :-)
>>>>
>>>> Thanks again,
>>>> **Paul
>>>>
>>>>
>>>>
>>>> Ben Barrett wrote:
>>>>> Hmm.  My setup is almost identical to yours, and I have had good luck,
>>>>> although there are some differences:
>>>>> * I run my torch in a wind-free environment.  My own movements are
>>>>> visible in the pilot flame of my fuel-saver, but not on the torch at
>>>>> all.
>>>>> * I have a smaller tip, #0/"aught" IIRC, but still a victor
>>>>> oxy/propane tip on a clone torch body.
>>>>> * I tend to keep my propane regulator around 3-5 PSI, and the oxy
>>>>> around 20-30... sorry for the range here, but I honestly don't know
>>>>> how accurate that is anyway (is an acetylene regulator but was new).
>>>>> When the tip was new, I got about a 30" long flame, much longer than
>>>>> anything I had seen on oxy/acetylene, very narrow and tubular and
>>>>> well-formed, and I was told that I should be able to cut pretty far
>>>>> away from the tip if I had good enough control to manage it.  The tip
>>>>> has had some use now and not much cleaning but still maintains ~20" of
>>>>> clean narrow cylinder of flame... now just recently I had taken to
>>>>> running it slightly oxygen-rich, because of the increased intensity of
>>>>> heat, which does seem to shorten the flame from its maximal length.
>>>>> I might've been running the propane closer to 6 or 7psi in the
>>>>> beginning, too, but have mostly been using this setup for heating (not
>>>>> cutting) but the oxy lever is out of my way when the torch is clamped
>>>>> next to the pilot.  I don't know what to suggest to you, since your
>>>>> scenario sounds so similar, and hopefully I'm not overlooking any key
>>>>> differences.  My initial level-setting procedure for the torch-body
>>>>> needle valves seems identical to that of oxy/acetylene, I first bring
>>>>> a fuel-only flame off the tip then add oxy.  Wind is a foe of either
>>>>> =/
>>>>> I have a feeling that propane mixtures need a little more "oomph" to
>>>>> light, something about the fuel being so heavy and syrupy, but I can't
>>>>> quite quantify that.
>>>>>
>>>>> Best of luck,
>>>>>
>>>>> Ben
>>>>>
>>>>> P.S. - my rig has cut before, and was reported by more experience
>>>>> hands to be quite capable, and just fine as expected.
>>>>>
>>>>>
>>>>> On Sun, Nov 8, 2009 at 7:16 PM, Paul N <crosspein at sbcglobal.net> wrote:
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