a good clean cut

admin

Ya I know this is basics 101.  I am practicing trying to teach myself enough to get started fencing soon. When I use my cutting torch the cut does not look like any of the pictures in the books. It just looks like melted gunk. sometimes I have to go back and cut again because the metal behind me (Slag?) melts back together again. One of the books I am reading notes you may have a little slag holding together and can tap lose with a hammer but this is pretty solid when tapped with a 22 oz hammer. I suspected the fire is too hot but I tried cutting back the acetylene as low as it would go without poping and going out - same result. Is it possible the tip I have is too large? Sorry no pics until I can figure out how to upload from my wifes camera. Maybe tommorrow or Saturday. I am working on 1/8 steel, using a 0 tip on a victor 100 torch. Books using as a reference - victor welding guide  and welders handbook from hp.using about 4 psi on acetylene and tried both 10 and 18 psi on oxygen. Hope this gives you enough info. Don
Reply:Your ratio could be a tad low. You will hear of ratios from 1:4 up 1:7 on the Acetylene to Oxygen . I run around 1:6 to 1:7. The type and cleanliness of the material being cut has a fairly big impact on the quality of the cut.
Reply:on material that thin i would angle my torch in the direction of the cut, it helps quite a bit actually.Nothing Ever Got Done By Quitting, Never Give Up.
Reply:Id say jack the oxygen up... I run 4 psi on acetylene and 25 psi of oxygen on a 0 tip. I'm no expert on precision torch cuts but it works for me. thats probably why your refusing your slag, or your moving too slow.Last edited by CaptainWilly; 02-15-2008 at 03:42 AM.I like to party!
Reply:I used to be able to make a pretty smooth cut with a torch until age and hands starting to shake kind of messed that skill up. Over the years here is what worked for me. Leave the Meco torches alone, leave the light weight torches alone, get a full size torch. Harris has a good one but is still a little light weight. I use Victor, the 315 mixing barrel and corresponding cutting head, the weight makes it hang steadier. Make the biggest pile of bones you can, muscles wiggle and shake, bones don't. In other words brace your hands and arms on something solid, even part of your body if you can. The steadier you are the smoother your cut.Tip size and cleanliness is extemely important. I cut every thing from 16 ga. up to 3/8" with a 00 tip. Even use it on 1/2" if I'm not cutting a lot of it. I use 10# acetylene and 40# oxygen untill I go over 1/2" thickness. The angle of the tip to the material makes your cut clean with very little slag left. The cutoff should just drop off. I keep my tip at a 90 degree angle to the metal on 1/4" and up. Roll the tip toward the direction of you cut on 3/16" down. The thinner the material, the more angle. 12 ga. on down I have torch at about  a 10 to 15 degree angl to the metal. Start your cut on the thin stuff and get it out in front of your tip. With a little practice you can keep the cut 2,3,4 inches out and you will have very little slag.With the pressures I use I can vary the cutting preheat quite a bit. I usually turn the acetylene on to where it flares about 2 1/2" from the tip and then add oxygen until the flame is neutral and when pressing the cutting lever the torch makes a ripping sound. You can adjust your torch from this point for thin to thick. With practice you will learn the correct travel speed.One other thing, the cleaner your metal, especially on the bottom, the less slag will remain on the metal.Sorry if this reads as lecture, it's not. Just trying to pass along something that has worked for me for a long time.
Reply:Originally Posted by OldtimerI used to be able to make a pretty smooth cut with a torch until age and hands starting to shake kind of messed that skill up. Over the years here is what worked for me. Leave the Meco torches alone, leave the light weight torches alone, get a full size torch. Harris has a good one but is still a little light weight. I use Victor, the 315 mixing barrel and corresponding cutting head, the weight makes it hang steadier. Make the biggest pile of bones you can, muscles wiggle and shake, bones don't. In other words brace your hands and arms on something solid, even part of your body if you can. The steadier you are the smoother your cut.Tip size and cleanliness is extemely important. I cut every thing from 16 ga. up to 3/8" with a 00 tip. Even use it on 1/2" if I'm not cutting a lot of it. I use 10# acetylene and 40# oxygen untill I go over 1/2" thickness. The angle of the tip to the material makes your cut clean with very little slag left. The cutoff should just drop off. I keep my tip at a 90 degree angle to the metal on 1/4" and up. Roll the tip toward the direction of you cut on 3/16" down. The thinner the material, the more angle. 12 ga. on down I have torch at about  a 10 to 15 degree angl to the metal. Start your cut on the thin stuff and get it out in front of your tip. With a little practice you can keep the cut 2,3,4 inches out and you will have very little slag.With the pressures I use I can vary the cutting preheat quite a bit. I usually turn the acetylene on to where it flares about 2 1/2" from the tip and then add oxygen until the flame is neutral and when pressing the cutting lever the torch makes a ripping sound. You can adjust your torch from this point for thin to thick. With practice you will learn the correct travel speed.One other thing, the cleaner your metal, especially on the bottom, the less slag will remain on the metal.Sorry if this reads as lecture, it's not. Just trying to pass along something that has worked for me for a long time.
Reply:I agree more oxygen pressure.  Also try moving faster.  If you are going to be doing a lot of cutting of thin stuff you might like propane.  I have heard that is better at not melting back closed behind the cut since it has less heat.  But I have not tried it myself yet.  Angling the torch in the direction of the cut also helps a lot.Good LuckMe!
Reply:Thanks very good and useful answers all. I will give it a try tonight or tommorrow after work - I knew welds had to be clean but not did not realize it important when cutting. These pieces were not bad, but I will hit with a flap wheel first and bump up the oxygen. I was moving pretty fast anyway - as fast as could and have the control I wanted.Oldtimer - Lecture? No -just the answer I was looking for.  THANK YOU The only problem is if you guys keep giving these good answers I'm gonna keep asking these newby questions. Thanks again to all Don
Reply:When you guys talk about angling the torch are you using push or pull method? Thanks.Daniel 5:23
Reply:InTheSticks, ask away. I may not give you the same answer as others but if I tell you a technique it will be something that has worked for me for a long time.baddarryl, I'm right handed so I try to cut to my left if possible. Roll your torch over so your tip is pointing to your left. The thinner the metal the flatter your torch will lay to the metal. I can carry a cut in 14 and 16 guage 8 to 10 inches in front of the torch if there is no wind.
Reply:push the flame
Reply:Listen to the oldtimer because what he is telling you is right. I can run a torch forward, backward, left hand, right hand, upside down, just about anything you can do with one. Seldom ever use a grinder on the cuts just roll it off with a chipping hammer and weld it. He taught me how. If you can't hear that rip he is talking about, your torch isn't right and it usually means it needs cleaning. It makes all the difference in the world in how clean your cuts come out. You don't control your cutting air with your regulator you feather it in with your trigger. I've used propane for cutting because I was forced to and it leaves a lot to be desired as far as cleanliness goes. Unlike acetylene you do have to grind your cuts because propane contaminates it and acetylene does not. I agree on the torches as well. I really like my Harris for O/A welding, but prefer my Victors for cutting. I also have a Uniweld cutting head that looks just like, and cuts just like the Victor. You can get Victor compatible tips that are cheaper than the Victor. I tried them and I go ahead and spend the extra for the Victors as there is no comparison. On the thin stuff a 00 is to your advantage.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:Oh, and you always push with a torch, or as he told me when I was just a pup, keep your heat ahead of your cut. Now in certain circumstances you will pull, but that is almost exclusively when using a scarfing tip. Oh, scarfing tip means a wash tip. I keep forgetting that seems to be an oilfield term.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:I just changed over to propane about three weeks ago and for most applications, I will never go back to acetylene.I have cut with acetylene for about forty years and always had the problem of the cut slagging back together at times. The propane has completely eliminated that problem, almost as clean as a plasma cutter for me.I will admit the propane is a little tricky to light and get adjusted just right, but I think I have it about figured out. The hardest part is getting used to holding the tip about a half inch above the metal to get the best cut, also it takes a little longer when you are piercing a hole in a heavy piece of metal.I will see if I can get some pictures of my cuts with it, but it may be a day or two as it is supposed to rain all weekend here.
Reply:With Oxygen-Acetylene, I've always used 30 psi Ox. and about 6 psi Acet. BTW, once you cut you can't really go back over a ragged part to do it again since most of the carbon is gone. At least that's the way I heard it.I also generally use a piece of metal as a guide as well. With a guide I can get excellent smooth cuts on steel.Last edited by gnm109; 02-16-2008 at 08:03 PM.Miller Millermatic 252Miller Syncrowave 200Liincoln AC-DC 225Victor O-A Set
Reply:On the really thin steel, you might want a  000 tip  (if using a victor, on acetylene . ) I don't know if anyone mentioned, but keep your tips perfectly clean; I mean the orifices, make sure you get a set of tip cleaners, if you haven't done so , yet. the smallest  size for 00 &000  bend & break  SO easily, you should have at least two sets on hands always . The individual sizes are available separately , but some dealers refuse to sell them , they want to sell the sets - more profits. Don't be afraid to ask small details , otherwise it might take a long time to learn everything by yourself .[SIZE="5"Yardbird"
Reply:I should NOT have said "everything".  nobody will ever learn all there is to welding . we don't live long enough . and , new technology is evolving constantly .[SIZE="5"Yardbird"
Reply:Oh, and you always push with a torch... Now in certain circumstances you will pull, but that is almost exclusively when using a scarfing tip....
Reply:Just so we don't confuse the newcomers.....Pulling or Pushing a torch is relative to the operators body.  In order to work properly, the torch should be inclined in the direction of travel to get the maximum benefit from the pre-heat jets.One can cut Left to Right, Right to Left, Towards your body, Away from your body, etc etc but the torch inclination in the direction of travel is the same.  Laying down the torch like the OldTimer said just directs the pre-heating further in front of the torch to help prevent melt through.Making a pile of bones works REALLY GOOD.Resting your free hand onto your work and supporting your torch hand is extremely effective as well.When doing long cuts, find a piece of 1 1/4" angle iron, or 3/4" flatbar - something that will work well with your particular torch tip - and set up a "fence" to run your tip against.  Then all you have to do is concentrate on keeping your tip to work height, and tip angle consistent to make a nice, clean cut.Same tip works for plasma cutters.Hope that helps.Later,Jason
Reply:Well I may have a ways to go but apparently I'm trainable. Cuts looked great - postition of the torch made a lot of difference. bumped up the oxygen and cleaned my test piece. Tommorrow I will give it a  try on some pipe.  I will also try welding and the 0 nozzle  is not going be enough for the pipe  so when i ordered a 3 nozzle I also ordered a 000 cutting tip. (yes Jolly Roger both are real Victors - I figure I have enough problems learning without wondering if my equipment is up to speck). Bottom line  guys I listened and it worked Again ThanksDon
Reply:I go seven on the acetylene and 40 on the oxygen. If you are hot enough, with enough cutting oxygen pressure, it will get rid of the slag. Rarely is anyone too hot. I set the torch to a perfect burn, by turning on the acetylene until it pulls off the torch and then I just shut it down until, it sticks to the torch once again and then I add short of the point it came off last time. After many years I just know the right settings, but this is how I get to them on a new torch. Then I add oxygen until the small blue points coming from the heating tip, do not change when you hit the cutting oxygen fully. If they change you still have too much acetylene, or if the acetylene is set right, not enough oxygen. You set the heating tip oxygen with the knob closest to the torch head. The main oxygen valve at the hose is supposed to be wide open to feed the cutting handle valve. The acetylene valve at the hose you adjust till the flame just does not leave the head. As someone mentioned a slight angle of the tip towards the direction of the cut. If you are making straight cuts? I actually will rest the tip on the work once I start the cut, and use a straight edge to guide the torch. But I keep the torch heavily angled towards the direction of the cut. Three or four degrees. If I am making circles I make a compass out of the torch, a compass that has a pin that I place in the center of the circle. I have cut heavy diamond plate to make manhole covers like this. I start my cut with the torch above the work. I preheat very well, let me stress this, very very well. When I see a hot even slag forming I hit the cutting oxygen and go. Zero tips are funny. They tend to clog easily. I like a number two for almost everything up to 1" stuff. Does it eat more oxygen sure. But for me it is worth it.        Sincerely,             William McCormick
Reply:The stink alone is enough to keep me away from propane and the only time I ever have any meltback is on really thin stuff when I can't get the torch on it in any position except straight in, then it's whack it once with a chipping hammer and it's separated anyway. On clean metal (meaning no scale) my cleanup amounts to the same with O/A as it does with a plasma. The things you can't do with propane are the reason I use acetylene. Can't do anything with propane that you can't with acetylene.I'm really picky on my cutting and tried the imposter tips just to see how they worked. Also had to prove to my business partner there was a reason they only cost 4 bucks apiece. Just posted my experience, but the Victor does make a difference.Regarding the going back after making a cut. Don't know where ya heard that you can't but it is purely misinformation, at least with O/A, can't say for other gases. I've never used a 000 for anything. I use the 00 even on 20ga. Use it on everything through 1/2 and have gone as far as 1" with it, but not if I had much cutting to do. Over 1/2 I usually just skip to a 1 because it is normally 1 inch. Just don't seem to cut much 5/8, 3/4 or 7/8.The difference between art and craft is the quality of the workmanship. I am an artist.
Reply:William, I pretty much agree with most of your post, but I never rest my tip on anything. As far as pressure I always ran 100' of A/O hose on my rig so you have some pressure drop. Shorter hose, less pressure. As far as getting to much heat, that's what makes those slaggy, raggedy *** cuts on thin stuff. I never have had any more trouble with 0 and 00 tips getting dirty easier than bigger ones. Maybe cause I don't rest my tip on the metal I'm cutting,LOL. It has to be 1 1/2" or just junking out something to make me get out a #2.As far as using propane for cutting, the only people in my part of the world that use it are junk yards cutting stuff to fit in trucks and railroad cars. I've also seen a few farmers use it.
Reply:Originally Posted by Jolly RogerRegarding the going back after making a cut. Don't know where ya heard that you can't but it is purely misinformation, at least with O/A, can't say for other gases. .
Reply:Originally Posted by Jolly Roger I've used propane for cutting because I was forced to and it leaves a lot to be desired as far as cleanliness goes. Unlike acetylene you do have to grind your cuts because propane contaminates it and acetylene does not.Denrep, please educate me on the things you can't do with acetylene. I'm not being a smarta$$, I'm really curious.
Reply:Originally Posted by OldtimerDenrep, please educate me on the things you can't do with acetylene. I'm not being a smarta$$, I'm really curious.
Reply:Originally Posted by gnm109A good example is noted in the poor O-A cutting characteristics of stainless steel. Extremely low carbon percentage being the principal reason. This is well-known.
Reply:Originally Posted by gnm109BTW, once you cut you can't really go back over a ragged part to do it again since most of the carbon is gone.
Reply:Thanks,Denrep.I didn't realise it was that versatile but I didn't see anything that I can't do with acetylene except buy it at the liquor store.
Reply:We have propane and acetylene setups in our shop.They both work well. Acetylene burns hotter, less preheat time. I think a clean, properly adjusted and sized tip for either will out perform a dirty and or incorrectly adjusted tip of the other. I think I prefer acetylene, but after denrep's glowing review, I may have to give propane another chance.They don't sell propane at the liquor stores in PA.
Reply:It's been interesting to learn about using propane to cut. ThanksI will mention I cut some pipe today. I had been wondering how it would do - cut just like the flat stuff except had to stop in the middle and roll it over. I'll  cut a saddle or two for practice next time I get a chance. Some of this may have parafin in it - havent really looked yet.  Is that any kind of an issue?Oldtimer I sent a pm but just curious about something. Jolly Roger said Fluvanna was somewhere close to you - are you near Lubbock? I am about 7 miles outside of Midland - If so Hey Neighbor. Don
Reply:Originally Posted by Oldtimer... I didn't see anything that I can't do with acetylene except buy  it at the liquor store.
Reply:Come to think of it Denrep I saw your avatar come through here the other day headed North - he may have been going to Fluvanna. Good luck in catching him. Don
Reply:Originally Posted by Black WolfWrong again.  In the oxy-fuel cutting process, you heat up the metal, and introduce Oxygen to oxidize the IRON content.  You make IRON OXIDE also known as RUST.  If you need to go over a "ragged part" again, simply take a chipping hammer and knock off the existing slag aka iron oxide, and have at it.Carbon content has absolutely nothing to do with it.Sorry to be singling you out, but you are the one most out in left field, and your information is incorrect.
Reply:Originally Posted by gnm109I get the feeling that you enjoy singling people out. I'll add you to my list and just lurk until you say something wrong.
Reply:InTheSticks, I grew up on the edge of the breaks northeast of Lamesa which is just on top of the cap west of Fluvanna. I live in New Mexico southwest of Lubbock and nothwest of Midland. It's about 15 miles further to Midland. My wife goes to a cardiologist in Midland. We are in Midland every month for a blood test. Nice town.Denrep, na, I don't think so. If I could get propane at the liquor store I probably would but we don't have liquor stores in New Mexico anymore. Drive up windows were outlawed several years ago because we had too many drunk drivers. Between that and the fact that you can buy hooch at Walmart, Walgreens, and every grocery store and convenience store around liquor stores have gone the way of the dodo around here. Still plenty of drunk drivers tho.
Reply:InTheSticks, I guess you got tubing to have parafin altho I've seen plenty of line pipe with it too. Depending on how much is in the pipe it can range from a little fire blowing out of the pipe to a real mess. Running out on the ground in a stream and on fire. Then you have to clean that sticky, greasy mess up after the fire goes out.
Reply:I have found that all the information sofar is very true ,But I have found that any thing under 3/16 is cut faster and cleaner with a grinder and the new cutoff wheels, saves time grinding and cleanning before and after the cuts. The price is about the same if not cheeper than the gasses.Life is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:asemaster - I agree sounds easier to cut  but to be honest though this has been learning and practice. 1st project will be to start putting saddles on pipe ends and that seems like it would require special equipment to cut. If there is an easier and cleaner way let me know. thanksOldtimer - Sorry you have to make that drive but yeah I like it here. Dont know if there is anything in the "pipe" yet -just finding out if it was an issue to look for. Sounds like it is. I put "pipe" in quotation marks because I am sure you and several others have encoutered what I am really using - pump barrels. Been calling it pipe because pump barrels seems to confuse folks. I will try practice welding later this week. I hope to quit screwing around learning how and start building something soon after. I was told they are actually low grade stainless but they are rusty as the dickens and cut just like the mild steel I bought for practicing on. will weld a sample then beat the heck out of it with a hammer like I have been the practice steel. Seem to learn a lot that way. Fun too, for some reason. Sorry so long winded all Don
Reply:Yep, I know what a pump barrel is. Make good cheater pipes. Never encountered one that was stainless. Ran into a couple probably 40 years ago that were bronze. Haven't used one for anything in a long time but the last ones I messed with seemed to be pretty high carbon. You can cut saddles with a cutoff saw and I've cut a bunch on really thin stuff. I built a bunch of fence panels to go around oil wells in town and they had to be light so they could be removed easily to work on the wells. They were made out of galvanized top rail for chain link fence. That was really a lot of fun. A tip on cutting saddles. Learn to cut them free hand with a torch. I cut them on 1" up to 4" sch 40 or 80. After you learn how it is really fast.
Reply:No need to guess at all of these things.Just get a VICTOR pocket welding guide at any wekding supply and it gives the exact pressures for each welding tip and cutting tip and torch size.Keep the torch perpendicular to the work surface and you will get a good cut just like the atomatic machines.If you are getting slag and melt together, your tip needs to be cleaned or replaced.Nothing like a new tip for getting a nice clean cut.
Reply:Originally Posted by asemasterI have found that all the information sofar is very true ,But I have found that any thing under 3/16 is cut faster and cleaner with a grinder and the new cutoff wheels, saves time grinding and cleanning before and after the cuts. The price is about the same if not cheeper than the gasses.
Reply:yes I'll agree on the circles and on the practice, But thought, da, I would just give some other input into cutting cleanly . the old timers being cheap would turn off the acy.after the cut started and just use oxy. to make their cuts ,known as oxygination or rusting.Life is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:Asemaster, I broke out in the oilfield in '69, spent a year in a gas plant before that and welded in a potash mine for 2 years before that. That should qualify me as an oldtimer like my handle says. I have never ever seen a welder start a cut and turn off his aceytlene. Didn't say it can't be done, it can and I have done it just to prove you can. When I started oilfield welding I worked with an old geezer that was 74 years old. He said his first portable rig was a truck with an acetylene generator on it, no welding machine. He didn' turn off his acetylene either.
Reply:what you say is just what I was getting at. better at hands on than writing things out. I have used a welding tip to cut very thin tin when doing body work. the things we find out that can be done if we just try it.Life is tuff,so be sharp  lincoln sp 100  cutmaster101  miller bobcat  miller 250 mig  $thousands in snapon
Reply:A lot of my posts are about cutting and welding using O/A heres one using some guides. http://www.weldingweb.com/vbb/showthread.php?t=17591 hope this helps and Safety first!!! Victor SuperRanger O/A                                         Solar migLincoln Powermig 140Southbend 9in lathe350# kohlswa anvilMiller Maxstar 150 stl etc....
Reply:I used propane &oxygen , for machine burning , usually 3 torches at once, sometimes 5 torches ,at Mare Island shipyard ,the last 3 years ,before they shut down the yard 1991-1994,on swing shift . We had the gasses piped into the shop. 750 gallon tank of propane;2,000 gallons of liquid oxygen. the only reason we used propane ?it was much cheaper, NOT better. being piped from one large tank saved a lot in wage costs , & a lot of time . worst of all was Kaiser Steels' use of natural gas for burning . hard to use& very dirty.  Years ago, my local welder supply did a cost analysis of propane  VS.  acetylene and acetylene  won out , for an average guy welding , where he could not use a huge tank , to get max savings . He started out his calculations using welding industry figures,- He was a friend & did not try to take advantage of me .[SIZE="5"Yardbird"