air-carbon arc cutting

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I have a Linde 235 Amp AC machine. I was thinking about setting it up with a torch for air- carbon arc. What would be reasonable expectations for this setup in terms of metal thickness? Or would I be better off with O/A? Which method is easier to master? I have a small O/A now, can't cut much thicker than 3/8". I want to cut some train rail.TIA, Big BMiller Challenger 172Miller Thunderbolt AC/DC 225/150Miller Maxstar 150 STLVictor 100CVictor JourneymanOxweld OAHarris O/ASmith O/A little torchNo, that's not my car.
Reply:I'm not sure your machine would really run an airarc. They list the minimum AC rod as 3/16" and the minimim amps as 200amps to 250amps.I'd just use the O/A. Define "small" If it's one of those "porta-torch" kits with the "MC" acet, then no you'd need bigger cylinders. I doubt a "B" sized acet would work due to the witrhdrawl rate, but it might be possible.I've cut rail with my torch with only a 75cf acet. cyl and 100cf O2. Most of it is how you set the torch and the tip in the torch. Another big thing with a smaller torch is to get the rail hot first. Sit there and run the flame back and forth over your cutline to heat up the rail. You don't need to turn it bright red, only start getting the heat in it before you start the cut. Then start the cut and go to it. I want to say my tip is a "0" or a "1" in my torch, and my settings are usually 4psi acet and 45psi O2 for something like this. Take your time and don't rush, but don't go too slow, you need to adjust your speed as you change thicknesses on the rail..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:Hello bigb, initially I was going to post that you couldn't operate an air carbon arc gouging unit from your AC machine, upon further investigation I did find that my thoughts were incorrect, I have included a link that describes the process and includes it's limitations and requirements, http://www.weldguru.com/CAC.html. It does specify that special gouging rods are required to be used with AC current. I have never used AC current for air carbon arc gouging, always DC, I don't believe that AC is likely that great of an option as it isn't readily discussed in most descriptions of the process. My familiarity with AC carbon arc use has been as a twin-stick method used years ago for brazing and soldering with arc welding machines. I will be interested to hear of how your results come out if you decide to try to air carbon arc gouging with your machine, please keep us informed. Best regards, Allanaevald
Reply:Gouging with AC current is more commonly done on nickle and chrome based materials as the rapid switching of polarity helps to push "sluggish" materials around.Have we all gone mad?
Reply:Carbon arc gouging is rough on machines. It's fun as all get out to do. But you really should have an industrial grade machine to do it. In addition to the welder, you need a serious air supply as well. O/A would be the way to go. Right size tanks, and cutting tips and you should be good to go.
Reply:Have you considered using a bandsaw?  It's slow going, but unless this is a really heavy rail, or you're mitreing it, a portaband should be able to chew through it.  It'll leave a cleaner cut surface too.If this isn't an option, then oxy-acetylene will get the job done with the right size tip. Originally Posted by bigbI have a Linde 235 Amp AC machine. I was thinking about setting it up with a torch for air- carbon arc. What would be reasonable expectations for this setup in terms of metal thickness? Or would I be better off with O/A? Which method is easier to master? I have a small O/A now, can't cut much thicker than 3/8". I want to cut some train rail.TIA, Big B
Reply:Thanks for all the advice, I have decided to first try to get a bigger cutting tip for my Pro Weld torch, if I can find one. My tank is a "B" size. I am going to upgrade both tanks to bigger ones when I can afford to, or maybe I'll get lucky and find a good Victor or Smith setup on Craigslist.Miller Challenger 172Miller Thunderbolt AC/DC 225/150Miller Maxstar 150 STLVictor 100CVictor JourneymanOxweld OAHarris O/ASmith O/A little torchNo, that's not my car.
Reply:You will want to watch the withdrawal rate on a "B" cyl. They recommend 1/10th currently, and 1/7th previously as the max withdrawal rate. A "B" is 40cf, so you are looking at 4 to 5 1/2 cf per hr. That means you are limited to like a 00 Victor tip.Here's a chart that lists gas usage by tip size.http://www.hoopersupply.com/tipchart.htmlYou might think about using propane rather than acet. You'd need to make a few changes to things like the tip and the hose, but you could use a standard 20 lb propane cyl that you probably already own. There's been any number of threads on cutting and heating with propane..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:BigB - What's happening? A single cut? Rail can be scored and snapped too you know.A slicing wheel on a hand grinder makes a nice score.The small torch will cut it. Crank up the O2, start diagonally on a thin edge and roll the torch to direct the "burn" to preheat the upcoming cut. Save the wheel flange for last.I heard that a small tip can have the cutting orifice drilled out to increase cutting range, without increasing fuel witdrawl rates. You'll have to investigate that modification for yourself.Good LuckLast edited by denrep; 03-14-2010 at 11:49 PM.
Reply:I have a 5 foot section and I want to make 5 anvilsDSW, thanks for the chartLast edited by bigb; 03-14-2010 at 11:57 PM.Miller Challenger 172Miller Thunderbolt AC/DC 225/150Miller Maxstar 150 STLVictor 100CVictor JourneymanOxweld OAHarris O/ASmith O/A little torchNo, that's not my car.
Reply:You'll be okay. You're probably only cutting 1.5" at the thickest.I've cut 4" pins with a porta-torch.Good Luck
Reply:You only need big tips if you're piercing.  You can cut suprisingly thick plate with 0 or 1 tips.  I've done 2 inch on a #1 tip but just cranking up the O2 a little.  However, if you start with too small of a tip for piercing, you'll preheat for a long time then blow about halfway through the plate before the molten puddle gets redirected to your scalp.
Reply:use what ya got and turn the oxy up.  I've cut 3" plate with a 0 I think.  It was the smallest tip we had at work and the boss said it couldn't be done.  10" dia circle dropped right out.  I did have to drill a pilot though, I wasn't about to try piercing that.My name's not Jim....