cutting torch woes
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Senior User
Joined: Apr 2004
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cutting torch woes
just got a cutting/welding torch setup, i've used them before when they were already set up. what do i set the regulators at. all the book said was not let the acetylene go above 15 psi i think.
i think i can figure the **** and stuff out on the torch its self, just dont know how to set the regulators.
also its a new torch kit, i had the oxy bottle refiled, the acytl. bottle is no telling how old, that sfuff doesnt go bad does it, cause the bottle is over half full.
i think i can figure the **** and stuff out on the torch its self, just dont know how to set the regulators.
also its a new torch kit, i had the oxy bottle refiled, the acytl. bottle is no telling how old, that sfuff doesnt go bad does it, cause the bottle is over half full.
Tuned
Joined: Sep 2003
Posts: 483
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About 5 to 7 on acet and 25 or so on oxy. These are dependant on tip size of course and oxy a little dependant on metal thickness. There is a good handbook for under 5$ (I think) called Victor cutting and heating guide at welding supply stores. Open tank valves slowly and keep oil away from torches like you would avoid the plague.
FTE Legend
Joined: Sep 2003
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From: NY and VA
If you are going to do a lot of cutting, try propane it cuts well and lasts a lot longer than acet. It requires a special cutting tip, and you should have the hose that is made for acet and propane. Most of the scrap yards use propane.
Hotshot
Joined: Oct 2002
Posts: 18,488
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From: The Big, Oregon
The problem with propane is that it's a pain to get lit and it's a lower pressure. Mapp gas works really well, that's what I use at work. Cutting 2 1/2" plate on a 45* angle with a number 5 tip, running about 12-15 pounds on the Mapp, and 40 on the oxy. Of course, i could only go about 2-3 feet on a big bottle of oxy, between preheating and cutting. In your case, running acetylene, 20-25 on the oxygen and 7 on the acetylene would be about right.
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Senior User
Joined: Nov 2004
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From: Bothell, WA
The acetylene doesn't cut the steel it only heats it to the point where the oxygen can blow it away so supplying more than is required to start the cut is wasted. Your acetylene will last a lot longer and the cuts will be cleaner using lower pressures and the proper tip sizes. The amount of acet needed to efficiently start the cut depends on the metal thickness and tip size. Cutting depends on the oxygen flow. Try these settings:
1/8" mat'l - tip #00, acet @ 1-2, oxy @ 5-10
1/4" mat'l - tip #0, acet @ 1-2, oxy @ 10-15
1/2" mat'l - tip #1, acet @ 2-3, oxy @ 15-20
3/4" mat'l - tip #1, acet @ 2-3, oxy @ 20-25
1" mat'l - tip #2, acet @ 3-4, oxy @ 25-40
Don
1/8" mat'l - tip #00, acet @ 1-2, oxy @ 5-10
1/4" mat'l - tip #0, acet @ 1-2, oxy @ 10-15
1/2" mat'l - tip #1, acet @ 2-3, oxy @ 15-20
3/4" mat'l - tip #1, acet @ 2-3, oxy @ 20-25
1" mat'l - tip #2, acet @ 3-4, oxy @ 25-40
Don
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Senior User
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From: Bothell, WA
Safety tip: Make certain you have a back flow valve on the acetylene side of the torch to prevent the flame from blowing back into the acetylene hose. Things get exciting when your acetylene hose is on fire. It's worse if the tank valve itself get's on fire which is a very dangerous situation.
Safety notes:
1. The 15 psi number for the acetylene is listed because acetone is used to stabilize the acetylene in the tank and pressures above 15 psi will withdraw the acetone. That in turn could cause the acetylene in the tank to become unstable and explode.
2. Open the oxygen tank valve all the way. Just crack the acetylene valve slightly open so it just takes a quarter crank to close the valve if something does go wrong.
Safety notes:
1. The 15 psi number for the acetylene is listed because acetone is used to stabilize the acetylene in the tank and pressures above 15 psi will withdraw the acetone. That in turn could cause the acetylene in the tank to become unstable and explode.
2. Open the oxygen tank valve all the way. Just crack the acetylene valve slightly open so it just takes a quarter crank to close the valve if something does go wrong.
Elder User
Joined: Jun 2003
Posts: 686
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From: Edgewood, Wa
Originally Posted by GLR
If you are going to do a lot of cutting, try propane it cuts well and lasts a lot longer than acet. It requires a special cutting tip, and you should have the hose that is made for acet and propane. Most of the scrap yards use propane.
We tried propane at our shop for 6 months. Got all the new tips and such for it. Propane doesnt "cut" it spatters, is wastefull, and slow. we went back to acet, and will never look back.
also, scrap yards are not known for quality cuts, just rip and sell...
Post Fiend
Joined: Jan 2004
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From: Elkhart IN
make sure you keep the acet. tank upright. when you lay it on its side the acet. gets drained out of the honeycomb stuff that its disovled into in the tank. if you do lay it down make sure it sits for a while befor using it. when you by tanks, make sure you transport them standing up and down and chained up. its a big fine if you get pulled over and they are laying down. if you get in a accident and the vavle gets knocked off that thing becomes a flying missile.
Posting Guru
Joined: Apr 2003
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From: Indiana
make sure you keep the acet. tank upright. when you lay it on its side the acet. gets drained out of the honeycomb stuff that its disovled into in the tank. if you do lay it down make sure it sits for a while befor using it.
Just bought it today the place I got it didn't say anything about it. I got one of the little portable ones. Do I need to disconect everything before transporting?
My bottle didn't come with caps.
Does it hurt anything if I shut off my tanks and drain the lines after I'm done?
My tip says 0-3-101 second line says A 12mm. What tip do I have? I will mostly be heating things with it and cutting from time to time 1/8 to1/4 what do I set my guages to? When I was using it my flame was about a foot long that ain't right is it?
Also any tips, tricks, or oh my God run for your live type pointers will be appreciated.
I have used mapp gas a long time ago. should I use ace. Or somethingelse next time I fill? I'm looking for safety above all else.
Last edited by Chris_ce; Feb 21, 2005 at 02:17 PM.
Post Fiend
Joined: Jan 2004
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From: Elkhart IN
well im not sure on the tip issue, but i know that we always have our regulators at 7psi acet. and 25 o2. its fine if you drain the lines when your done, just the next time you use it, if you have alot of hose it can take a while to get acet to the tip, but this shouldnt be a problem with your setup. on the saftey issue, as long as acet is handled right its just as safe as propane. never turn your regulator for acet over 15psi as it becomes unstable and could cause an explosion. with a portable unit like yours you shouldnt have to disconnect everything durring transport just make sure your bottle valves are off. on your bottles, does it have some sort of safety device so the vavles dont get knocked off? when your adjusting the flame, you should turn the acet up until the black carbon smoke is almost all the way gone. you should then turn the o2 up until you have little cones inside the flame. hit the o2 handle and if the cones stay the same and dont get bigger its set right. hope all this helps
Senior User
Joined: Nov 2004
Posts: 305
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From: Bothell, WA
with a portable unit like yours you shouldnt have to disconnect everything durring transport
I have seen single settings used all the way up to 10 & 40 and I won't argue that they won't cut metal, they are however a waste of acetylene. The acetylene's primary purpose is to heat the metal till it starts to melt after which oxidation takes over and keeps the cut going. Try the settings listed above for maximum cutting efficiency and economy. While one setting may work for a wide range of metal thicknesses you will get cleaner & smoother cuts and save money using a setting designed to match the thickness of metal you are trying to cut.
Elder User
Joined: Sep 2004
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The reaction between iron/steel and oxygen is exothermic. The steel is actually burned, not blown off, by the oxygen. (OK, the oxygen does blow off a bunch of molten steel, but it's the generated heat that really matters).
It is possible to start a cut with a preheat flame of a neutral mixture of acetlyene and oxygen, get the steel hot, turn on the center oxygen jet to begin the cut, and then turn the aceylene off completely. The oxidation reaction between Fe and O2 creates enough heat to keep the cut going on its own, without any more acetylene. In practice, we keep the acetylene on anyway, but it is useful to understand the chemistry involved.
It is possible to start a cut with a preheat flame of a neutral mixture of acetlyene and oxygen, get the steel hot, turn on the center oxygen jet to begin the cut, and then turn the aceylene off completely. The oxidation reaction between Fe and O2 creates enough heat to keep the cut going on its own, without any more acetylene. In practice, we keep the acetylene on anyway, but it is useful to understand the chemistry involved.