Starting to think that Oxyfuel is impossible

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I'm starting to think that Oxyfuel cutting is impossible, and that anyone who can do it possesses some kind of magical ability.Most of my cuts are slag covered nightmares. My biggest problem is cutting through 5/8" plate, and it's exactly that; I can't cut through it. After not being able to break it off i flip it and to my dismay i didn't even cut all the way through about half of the plate. I go slow, I go fast, can't cut through it. I need a 5/8" plate for an assignment and I'm running out of time to turn it in. Suggestions? One idea I have is to go slug slow, to creep along, to make sure I cut all the way through, even if my final product is doused in slag. I'm just frustrated with this whole process. It's been nothing but a nightmare since I started it. Flux Core went well. Stick went well. Plasma cutting went well. Oxyfuel is just a huge weight on my shoulders. I mean, purely for the sake of efficiency, I find myself wondering why in the world any shop would use such a needlessly difficult process.Sorry, I'm rambling. Any advice would be appreciated. I need to cut this 5/8" plate.
Reply:Wayne did a very good job of explaining proper setup and operation procedures using Oxy fuel. He expanded on in detail a thread I started about it some time ago. His skill and experience is without question, credible and you can take it to the bank.Check it out.http://weldingweb.com/vbb/showthread.php...-cutting-torchExpert Garage Hack....https://www.facebook.com/steven.webber.948
Reply:What do you have for a torch and what tip size are you using? Is it clean or look like it was used to pound nails? A torch can actually be a precision tool if its treated properly. I cut a bunch of 2" plate last week for some drilling rig parts, just a normal work day. For 5/8" plate a number 1 tip should work fine for most people at about 30 psi oxygen pressure. With experience smaller tips and lower pressures will be possible. And being able to balance the flame comes into play also. It is a complex process... And pretty simple too.
Reply:Originally Posted by 7A749Wayne did a very good job of explaining proper setup and operation procedures using Oxy fuel. He expanded on in detail a thread I started about it some time ago. His skill and experience is without question, credible and you can take it to the bank.Check it out.http://weldingweb.com/vbb/showthread.php...-cutting-torch
Reply:Give us some information like what your gas pressures you were using and the tip size. Did you have the oxygen valve on the torch all the way open and use the valve on the cutting attachment to adjust the oxygen? If you have too small a tip, it's dirty and no preheat, it's not going to cut. You can do precision cutting with O/A if you practice and have the proper set up.
Reply:Originally Posted by 7A749Wayne did a very good job of explaining proper setup and operation procedures using Oxy fuel. He expanded on in detail a thread I started about it some time ago. His skill and experience is without question, credible and you can take it to the bank.Check it out.http://weldingweb.com/vbb/showthread.php...-cutting-torch
Reply:Originally Posted by Welder DaveGive us some information like what your gas pressures you were using and the tip size. Did you have the oxygen valve on the torch all the way open and use the valve on the cutting attachment to adjust the oxygen? If you have too small a tip, it's dirty and no preheat, it's not going to cut. You can do precision cutting with O/A if you practice and have the proper set up.
Reply:Originally Posted by Sm412I just need some tips. Do I need to go slower cutting through thicker plate?
Reply:Using propylene changes everything. You need higher pressure than acetylene for one thing and you don't use a neutral flame. Neutral flame means equal parts fuel gas and oxygen. Propylene uses about 2.5-3 times the oxygen of acetylene if I recall. Turn your fuel gas pressure up to about 10 and your oxygen to about 35 and adjust the flame a little more than just getting it to stay the same when you press the oxygen lever. It's already an oxidizing flame to begin with so more oxygen won't hurt anything. For cutting it doesn't matter if there's more oxygen. There's a stream of pure oxygen in the cutting jet. Is this propylene mixed with propane? I worked at a place that sold Chemtane that was added to propane to produce a hotter flame. You were supposed to hold the torch higher off the plate than you would for acetylene. It sounds like you were just too cold.
Reply:Originally Posted by DSWMaybe. Slag underneath gluing things back together often means you are too hot, aren't using enough O2 to blow the cut clear, or that you are moving too slow, or a combo of some or all of the above.I don't use propylene, so I can't say on your settings. With Oxy Acetylene, the gas pressure would be higher than I'd use and the O2 on the low side. I usually go 4/40 for most stuff or even higher on the O2. Speed is governed by how it cuts. I try to run just below the point where I start to outrun my preheat and loose the cut. Going super slow, allows the flames to melt the edges and cause the molten steel to flow back in around behind you. I cut slower on say 5/8" than I would say on 3/16" steel, but it's all relative. If I keep loosing the puddle and snuffing out the cut, I need to slow down. Otherwise I try to cut as fast as I can.Big tips help, but they are not absolutely required. I've cut plenty of 3" angle iron welded solid as a demo set in a ^ shape, cutting from thin to thick and back to thin again all in one shot without loosing the puddle using 00 tips. Trick is first to have a good clean tip and have the pressures set right and the torch adjusted properly. 2nd is to use the torch to preheat the cut line on the really thick stuff. If you use an acetylene flame to soot the plate, when it's hot enough to burn off the soot, it's usually hot enough to cut easily. When cutting I have to watch the sparks and adjust my cut speed. If I see the sparks flying straight thru, I'm usually good. If the sparks all all behind me, I'm probably starting to out run my cut. If I see a lot of slag starting to creep around the cut, I probably need to speed up more.
Reply:Originally Posted by Sm412What sparks will I get when it isn't cutting all the way through? Up and over, I assume?
Reply:Clean tip, clean tip, clean tip,  And oh,  Did I mention clean tip .     One hand should hold the torch,  the other like a knife blade vertical and rest the torch tubes on it.  Maintain a constant stand off and steady movement.    When you.pull the cut O2 lever, the neutral flame should stay the same length and you should get a visual "straight column" of oxygen up the middle of the flame tail all the way to the end of the full flame.Tiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:Thank you! I'll take all of that into consideration next time I cut. I'll go hotter and see if that helps the situation. Only thing is, my instructor was able to make the cut with the same settings and I'm wondering what they were doing that I wasn't. The only thing I noticed was he was steadier and more consistent than I was with how high he held the cutting tip. Maybe that will help too. Thing is, I just don't know. In any case, I'll master this by the time I'm done with the welding program.
Reply:If you look at picts of "clean" cuts, the ones that are done at the correct speed, the cut lines on the edge of the plate go almost straight down. As you start to out run the cut, the lines start to curve back in the direction you came from. If you go too slow, you start to loose those nice clean lines as the edges melt back behind the cut path.I think Wayne may have covered some of this in his videos, but it's been a bit since I watched them. His videos are a great example of how to cut well with a torch, and there's a lot of good info there that you can glean simply by looking at all the stuff going on. What the sparks look like, and so on..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Originally Posted by soutthpawClean tip, clean tip, clean tip,  And oh,  Did I mention clean tip .     One hand should hold the torch,  the other like a knife blade vertical and rest the torch tubes on it.  Maintain a constant stand off and steady movement.    When you.pull the cut O2 lever, the neutral flame should stay the same length and you should get a visual "straight column" of oxygen up the middle of the flame tail all the way to the end of the full flame.
Reply:Originally Posted by Sm412Thank you! I'll take all of that into consideration next time I cut. I'll go hotter and see if that helps the situation. Only thing is, my instructor was able to make the cut with the same settings and I'm wondering what they were doing that I wasn't. The only thing I noticed was he was steadier and more consistent than I was with how high he held the cutting tip. Maybe that will help too. Thing is, I just don't know. In any case, I'll master this by the time I'm done with the welding program.
Reply:My first set was Marquette. I learned to weld with it, but it was useless for cutting. Took it back to Grady Welding Supply, they sent it off for repair. Later I used somebody's good torch, what a difference! I now own Smith. It works as well as my unsteady hand can make it. When I need a perfect cut, I use a straightedge.An optimist is usually wrong, and when the unexpected happens is unprepared. A pessimist is usually right, when wrong, is delighted, and well prepared.
Reply:If your instructor took the torch and made a good cut with your settings, your problem is your technique.  My first wag is you are to shakey, and if you made a cut across a 5/8 plate that didn't go through, with all that slag blowing up around you, you probably are just a little nervous about the process as well.  I think a beautiful cut requires a steadier hand than a beautiful bead, because you can't make any sort of whipping or weaving motions when cutting.  As others have said, you have to make sure the sparks are going out the bottom of the plate.Grab a piece of steel to keep the flame away from your hand.  It can be almost anything, flat, angle, even round.  3/8 x 2 would work fine.  Lay it close to the cut line, but not next to it.  It is just to keep the flame from sending the heat across the top of the plate back to your hand.
Reply:You have to know how to set the flame correctly first. A combination torch (3 adjustment knobs) is generally more easy to use if your inexperienced at gas cutting. My settings are 6-8 acetylene and 35-40 oxygen. If your flame is not correctly set, your not going to get anything cut.A 0 tip is good for up to 3/4" material cleanly. Over 3/4" and I will go to a 1 tip.Last edited by snoeproe; 05-23-2015 at 07:23 AM.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:When I adjust the torch, I just ease down on the oxygen lever to find the sweet spot. I want the cutting cone to go out as far as possible from the tip. And sound like a jet engine. Then I know I’m going get everything that tip has to offer.  Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
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Reply:Originally Posted by CEPWhen I adjust the torch, I just ease down on the oxygen lever to find the sweet spot. I want the cutting cone to go out as far as possible from the tip. And sound like a jet engine. Then I know I’m going get everything that tip has to offer.
Reply:Was your instructor using propylene as well or a different fuel gas? Pictures would really help.
Reply:http://www.weldingtipsandtricks.com/...l-cutting.htmlNothing Ever Got Done By Quitting, Never Give Up.
Reply:Propylene has more BTU's in the outer cone than acetylene, that's why it's good for heating. Acetylene has more BTU's in the inner cone. Acetylene can only be used for welding because it is the only fuel gas to use an actual neutral flame rather than an oxidizing flame.Once you get the pressure, speed and temp right to get the cut going you should be fine. Oxy cutting doesn't technically need fuel once the cut starts. The oxygen from the cutting jet actually reacts with the molten steel and adds a lot of heat to the cut (you could actually turn off the fuel once things start going), it doesn't just blow out the kerf. Try cutting stainless with an OA rig if you want to see what just blowing out the kerf looks like.
Reply:You need to have the steel at a hot enough temperature and the cut may go a little ways with only the oxygen jet. People claiming you could keep the cut going indefinitely don't know what they're talking about. If the cut could go continuously, why does everybody using a cutting machine not turn the fuel off?
Reply:I said it was possible, not practical. The point was, the oxygen is burning the steel out of the cut not the fuel. The fuel is only there to get it to a critical temp where it will react with the oxygen and keep the leading edge of the cut at the right temp which in some circumstances would be possible from the heat of oxidation alone.
Reply:Have cut over 300mm without a flame. Got the plate red hot, started the cut and then turned off the fuel. It cut perfectly for about 100mm but as the plate lost temp the cut started to look chewed out.Only really good if you want to make some quick cash and bet your mates you can flame cut steel without a flame
Reply:Oxy/fuel cutting is basically rusting the steel away. Oxygen doesn't burn. The technical term is rapid oxidation.