o/a cutting help - settings?

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I am new to o/a cutting and am having a bit of a problem.  I am trying to cut some circles out of some very thin sheet metal and as I cut the hold closes up behind the torch.  At first I thought it was just slag that would chip off but when I was done the first one - I had to do a lot of grinding to get the circle loose.I am at 4 psi acetylene and my oxy gauge has markings for cutting thicknesses and it is at 1/8 (the lowest one)any tips or suggestions on technique to prevent this?  I have tried varying my speed but going slower just makes it worse, and if I go any faster it stops cutting.thanks for any tips.
Reply:IMHO You need to move Faster!_______________________OF COURSE I DON'T LOOK BUSY... I DID IT RIGHT THE FIRST TIME
Reply:Not sure what 'settings' to use,   My O2 is usually way up there and Acetylene is just off the red line a tad - all adjustments are done on the torch based on how its cutting.   If its closing up behind you then most likely you are not actually cutting, just melting it into submission.   O/A cutting is not about making liquid metal - if you are just washing out a puddle you need more pressure.  you might try moving up to the next larger tip, give you a wider cut (wasteful but helps sometimes)When any government, or any church for that matter, undertakes to say to its subjects, "This you may not read, this you must not see, this you are forbidden to know," the end result is tyranny and oppression, no matter how holy the motives.
Reply:Thanks for the suggestions.  I will try more heat (more acetylene, I guess?) and moving faster.  I definitely did not that I was melting it into submission mostly and at some places it just got nice and cherry and the o2 blew a nice path through it.  It seems that it is a delicate art that needs work to be mastered - I'll have to set aside some time to practice, not when I am in a hurry to get a project done
Reply:Cutting thin sheet with a torch is a total pain. You might try leaning the torch so the flame is pointing ahead a bit. That makes the line of the cut 'thicker'.
Reply:OP: Pictures of your setup and what you're trying to do would help. OA cutting isn't brain surgery, for that you'd need a sawzall. -JoeI can remember in the 7th grade my mom said "people will offer you drugs" by the 10th grade I was like, "where the hell are these people?"
Reply:Sounds as though you are over heating the material, the molten metal is flowing.  Once the cut starts you can lift the torch a bit to get the preheat flame off the material.  You don't need the pre-heat flame at all once the cut starts - the O2 will make the cut as long as you don't loose it.  This means making sure you have a good clean cutting flame, clean orifices in the torch tip.Hobart LX235Victor 250 Oxy-Acetylene Rig (welding and cutting)Bobcat 773F-350, 1999, 4x4, 16' 10K# trailerOutdoor Wood Burner - 10 cords/year
Reply:when cutting try to get the oxygen at 5 times the acetylene pressure. that said, look on the tinman tech site for a description of how to adjust a torch without trying to guess what pressures the gauges  areshowing.
Reply:Thanks for the pointers. I was able to get it done and played around with the settings a bit to get a better cut based on the info provided.  Now just have to keep practicing and getting better.
Reply:What size tip are you useing?Ranger 250 GXTSmith Gas Axe
Reply:To look up the gas pressures for different size welding torches, tips and cutting torches you need the VICTOR hand pocket guide.EBAY....$12.50 Used to be free when you bought a set of torches.http://cgi.ebay.com/WELDING-CUTTING-...8#ht_500wt_689A MUST HAVE.It works like this...Select the type of torch handle Performer,Journeyman etc., then the size 0,00, or 000 then the welding tip size, and that will lead you to the oxygen pressure and the gas pressure for that size torch and that size tip.Contrary to popular belief you don't just set all torches and tips to 5 lbs. and expect good results.Also if you are cutting... the tip MUST BE CLEAN. All of the holes clean.Last edited by Donald Branscom; 07-04-2011 at 11:58 PM.AWS certified welding inspectorAWS certified welder
Reply:The settings never change no mater the thickness of the material. All carbon steel can be cut nicely at 5 - 7 ACE. and 37 - 42 OX. The tip diameter changes for the thickness being cut.
Reply:Originally Posted by MrLeadManWhat size tip are you useing?