oxy/acetylene cutting

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ok guys any of you all have any tips for oxy acetylene cutting ?im past the gas welding stage now im on to torch cutting in school...  I find sometimes there is a fair bit of slag build up on the bottem of the pieces im cutting.??  Why is this ?  I think maybe when this happens im going to slow ?Any tips and hints would be appreciated.  Yesterday I was doing some really nice cuts but couldnt reproduce them today.
Reply:You might try cleaning your center oxy hole often. You should be able to see a long very straight oxy flame trail in the middle when you are adjusting your torch if not stop and clean it . Adjust your torch angle to lead at the bottom in the direction of your travel (only a slight angle). There is a lot of opinions on this next thing I do, but I like to "pre-heat" the line of cut by passing the torch over the steel several times prior activating the oxy lever. I only do it on steel over 3/8" thick. I assume the your oxy/fuel settings are correct and that the tip is of correct size. Hope this helps.
Reply:Lots of slag gerally means one of several things. You are too hot, the 02 presure needs to be turned up, the tip is clogged, OR you are moving too slow if the settings are close.Try moving faster. If you go too fast you'll loose the cut, but you should see an improvement in the lack of slag. At that point it's just slowing down a bit to keep the heat ahead of the cut. Remember nice and steady movement is key.Good luck.
Reply:More info would be helpfull.What changed from yesterday to today? Material, gas settings, tip size, dirty tip, how you were cutting? What are you cutting and what is you set up? Select proper tip size for thickness of material.inspect tip seat, area should be smooth and clean,cutting orifice should be free of obstructions or will result in poor performance and cutting efficiency. pre-heat orifices must be free of obstructions or will extend pre heat time and result in poor performance and cutting efficiencyinstall tipset gas pressure Check a oxy-fuel cutting chart or check your BOOK or with your teacher. Open the oxy and fuel tanks. Never stand in front of the regulators when turning on the tanks!Open the oxygen valve on the welding torch completely. Open the pre heat oxygen control valve on the cutting attachment and adjust the oxygen regulator to desired delivery pressure. Close the oxygen pre heat valve.Open the fuel valve on the welding torch handle and adjust the regulator to deaired delivery pressure. Close the fuel control valve on the torch. Open the fuel valve slightly and ignite the gas with a spark lighter.Continue to increase the fuel until the flame clears the tip by about 1/8" then reduce the supply slightly to return the falme to the tip.Slowly open the pre heat oxygen contorl valve until you get a neutral flame.Depress the cutting oxygen lever and adjust to a neutral flame. Flame is set and ready to cut. Pre heat metal to a chery red then move the torch in the direction you wish to cut.Moving too slow will allow the cut to fuse together, and too fast will not allow the metal to pre heat and the cut will be lost. Some pics would Waldo
Reply:Since you're in class, you may be marking several lines and cutting one after another. If so, you're overheating the piece. You need to quench after each cut. We used 3/16" in class and they'd heat up fast.I also agree with 'speed up'. If you don't out-run your cut once in awhile, you won't learn how fast you can go.9-11-2001......We Will Never ForgetRetired desk jockey. Hobby weldor with a little training. Craftsman O/A---Flat, Vert, Ovhd, Horz. Miller Syncrowave 250
Reply:a common misconception is to just turn up the oxygen pressure when things are going right.  Alot of people that ive met and work with have the "just turn it up and blow through it" attitude, and thats what makes a poor cut.  In general, you dont want any more pressure than is neccesary to get through the metal your cutting.  I cut alot of 1", and i use a number 2 victor tip, and about 35 psi of oxygen.  Excess oxygen pressure will create turbulence and will gouge the metal your cutting.Slow down, listen for that constant spray sound, watch your kerf.  Towards the end of your cut, the metal will be hotter, you can speed up to compensate.  You can also learn to control the amount of cutting oxygen by feathering the cutting lever.  You dont have to press it all the way down, use as much or as little of that lever as you need to make the cut.
Reply:Thanks for the advice guys.  The only thing that changed is that the tip was brand new yesterday when I used the torch but today everyone was using it so id say it was just an issues of a dirty tip.   I also noticed while adjusting the flame  I had the oxy adjusted a little too high and a couple of the pre heat flames went out until I turned the oxy back down a touch. Probably a sign of a dirty tip ???
Reply:the most important hole to keep clean is the large blowhole in the middle,  The other outter holes can be dirty, theyre just preheating.  What makes the actual cut is the stream of oxygen coming through the middle.  If it isnt perfectly clean the oxygen jet will disperse and cause gouges in the cut.  If you light up the torch and adjust to a neutral flame, then hit the cutting lever, you should see a perfectly straight line going through the middle of the flame.  If its not straight, clean the tip until you get a nice straight stream.  its impossible to make a smooth, clean cut with a dirty tip.
Reply:The tip has to be clean every time, even the preheat holes, as well as the face of the tip. The tip needs to be an appropriate size, the pressures need to be in the "sweet spot", and your technique needs to be solid. Get it all correct, and the cut will tell you so! Oh yes, I always cut perfectly, every single time!! City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:ok so yesterday my cuts were back to good but today they were hortrible..  Dirty tip again I would assume.   I do have another question though.   If I have a torch with a tip in it and I do not know the size to adjust the pressures how do I figure what to set the regulators at?   Or would I just adjust for a neutral flame right from the regulator and whatever pressure I end up with be the pressure I use ????Thanks
Reply:Tips are all marked on the outside to show the size. What I did in school, was go to my LWS and pick up my own tip for the school torches. No more confusion about tip cleaning! Swap in my own, make my cuts, then swap it out when done.  B.Y.O.Tip!But for pressure, 5 psi Acetylene and 30-50 psi Oxygen, depending on thickness, worked for me.City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny