Really lousy oxygen cut


This is my first, maybe second, attempt to cut something with O/A.
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As you can see, the edge is very lousy, full of dross, and just
generally shitty looking.
I believe that this is a 3/8" thick piece of metal. This was a 250
lbs, heavy stand that I did not need and cut up for metal stock.
So, the obvious question is, what did I do wrong. This was a Victor
cutting torch, oxygen pressure was about 25 PSI, acetylene pressure 7
PSI, hose was about 50 ft long.
My first thought here is that 1) I should have used a guide 2) I
possibly should have moved faster and 3) Maybe there is some trick to
blow away the molten dross.
Any thoughts on this?
i
Reply to
Ignoramus6669
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Now that is probably the worst cut I have ever seen! Looks like you have way too much preheat.
There was a whole discussion under 'Cutting Tips Oxy/Acetylene' in August.
My usual list of tips:
You must be absolutely steady and uniform!! Use a piece of barstock as a guide, practice pulling the torch towards you while maintaining the height with one hand and hitting the lever with another hand. This is the ONLY time I recommend having alcohol while working but half a beer may relax you enough to make a difference!!
Tip has to be clean. REALLY clean. Did I say CLEAN? File the tip flat, use a tip cleaner, take a look at the flames out of each hole, they should be perfectly symetrical.
practice on a piece of 3/8" plate.
4# on the acet, try 20# on the O2. Open the O2 valve on the torch body wide open, crack the acet valve a bit, light torch, add a bit of O2 from the cutting head valve, open the acet full. Adjust the cutting head O2 to make the inner and outer blue flames the same length. This is neutral flame and the hottest flame. Should be something like 1/4" to 5/16" from tip.
Set the tip of the inner flame on your workpiece (ie the 5/16" from above), find an edge to get started (You can plunge cut but not as a newbie!) Once you see a tiny puddle form, hit the O2 lever and start pulling SLOW and STEADY. The object is to get a cut that stays lit for the full length. If keeping it lit is a problem, up the O2 pressure to 25 or 30 psi.
Once you get a cut to stay lit for several inches, try to speed it up.
Once you get a full cut, it's time to fix the problems: your back edge probably looks like c**p. Check to see that the cut is in a straight line: if not, your guide needs work. If you have trouble losing the cut, you need to work on slow and steady. Take a look at the lines in the cut: they should be straight with just a hint of a bend at the far side. If no bend, reduce the O2 pressure. If gobs of slag, reduce the O2 pressure.
The object is to just use up the O2 as it reaches the far side. A perfect cut is much smoother than a hacksaw cut. A perfect cut has a very slight rounding on the near side from the preheat flame, a faint burr on the back side.
Ignoramus6669 wrote:
Reply to
RoyJ
You were holding the torch too far away and moving too slow.
But thats pretty common for people to do.
Pressures might be a bit high....what is your tip number?
Gunner
"Lenin called them "useful idiots," those people living in liberal democracies who by giving moral and material support to a totalitarian ideology in effect were braiding the rope that would hang them. Why people who enjoyed freedom and prosperity worked passionately to destroy both is a fascinating question, one still with us today. Now the useful idiots can be found in the chorus of appeasement, reflexive anti-Americanism, and sentimental idealism trying to inhibit the necessary responses to another freedom-hating ideology, radical Islam"
Bruce C. Thornton, a professor of Classics at American University of Cal State Fresno
Reply to
Gunner Asch
The worst? Blink blink....Crom....thats not half bad compared to some of the boys around my town.....
"Lenin called them "useful idiots," those people living in liberal democracies who by giving moral and material support to a totalitarian ideology in effect were braiding the rope that would hang them. Why people who enjoyed freedom and prosperity worked passionately to destroy both is a fascinating question, one still with us today. Now the useful idiots can be found in the chorus of appeasement, reflexive anti-Americanism, and sentimental idealism trying to inhibit the necessary responses to another freedom-hating ideology, radical Islam"
Bruce C. Thornton, a professor of Classics at American University of Cal State Fresno
Reply to
Gunner Asch
You do not specify tip size, I suspect it was too big. IMHO most people use tips that are MUCH too big. As always, your TIP MUST BE CLEAN and free of cutting orifice belling. Do yourself a favor and buy a NEW small tip and keep it clean and free of belling. My personal favorites are those with 6 very small preheaters and designed for use with cutting machine torches, (YMMV, the low preheat can make it easy to lose your cut if you are unsteady). A good demonstration of a real steady cut is to have a helper preheat the edge of the plate just to start the cut. then continue with O2 only and no preheaters.
Pressure required depends on hose size as well as length. Try raising O2 pressure a little, suggest ~40psi then reduce if experience shows your hand and speed skill is capable.
Guides are a crutch, and have their own problems. Learn to hold the torch steady and progress cut forward smoothly, watch the point of the cut and avoid melting the edge of the kerf. You must have good posture and comfortable body position with your weight well balanced on your legs and with a minimum of weight on your elbows.
2) I
This may be your basic perception problem, O2 torch cutting is a BURNING process and does NOT involve melting and blowing away dross. A proper cut will have very little dross as all the material from the kerf will be BURNED and reduced to little balls of iron oxide on the floor with little or none clinging to the cut or the underside.
Good luck, practice is required.
Reply to
Private
Size 1-1-01 Victor tip, 4# acet, 30# O2. Without being there, I can definitely say something's wrong. Maybe the way you set the torch. Open the acet and strike. Open it until the big floating boogers go away. Open the O2, and come up until you have cones on the outer ring of the tips about 1/4" long. Squeeze the handle and adjust the O2 to get 1/4" or so cones. Hit and release the handle a few times, and adjust O2 until the cones are the same distance at both times. You want the cones not to move when you hit the O2 handle . On acet, keep the blue cones just off the metal. On propane, you can go farther away. The oxygen does the cutting, the gas just heats it up.
Good luck.
Steve
Reply to
SteveB
Why don't you try grinding the paint off and then spend say 15 seconds going back and forth with the preheat flames and trying again. Do you have some number drills for cleaning the cutting orifice. Kind of looks like that is the issue to me. You can look at the flame with the cutting oxygen depressed and get an idea if something is less than desired. Are you sure the tip isn't a divergent bore? It also looks like a divergent bore tip with insufficient pressure just normal pressure for normal tip. In my opinion 3/8 is about as easy a thickness to cut as any thin can re fuse together and thick can take a steady hand. It isn't necessarily the guide as how smoothly you advance is generally the issue. Maybe 20 inches per minute for that stuff I imagine you could look up in victor's literature.
Fran
Reply to
fran...123
. Did I say CLEAN? File the tip flat,
Yes the victor tips (I have seen) are square on the end however I have noticed some of the genuine Harris tips are sculptured so that the copper is longer nearer the center. Acetylene tips, and the preheats angle in more than any other brand I have stuck drills in.
Fran
Reply to
fran...123
Not enough heat or to slow in the drag or to much moisture in the air... or all three...
I do plasma cutting - today it was great - 5% R.H. :-) - I also have a refrigerated dryer on it as well :-) Martin
Ignoramus6669 wrote:
Reply to
Martin H. Eastburn
"SteveB" wrote
iggy's post and description snipped;
I'm going to try to photograph the way I (me only) adjust the torch for cutting. It is infinitely easier to show someone than tell them. I also have a HD video camera that I will try to make a video of, and have my tekkie show me how to post it on line.
Steve
Reply to
SteveB
Iggy
It's a brain-buster trying to figure how to set up an OA cutting-torch.
What works for setting up an OA welding torch is "incomplete knowledge" for a cutting torch. The problem with the cutting torch is that you have the same oxygen pressure feeding both the cutting nozzle and the oxy-acetylene preheat nozzles.
Here's my scheme.
Forget about the gauges
Set the oxygen with no flame lit - the torch acetylene and preheat-oxygen valves are closed. Hold the cutting lever fully squeezed and play the oxygen jet on your hand. Visualise whether the propulsion of the jet should clear the kerf of oxide. You are not trying to create a pyrotechnic - you want a nice smooth reacting-away of the steel and its smooth fluid flow out of the cut.
Next - independently - set the acetylene pressure - exactly the same as for oxy-acetylene welding by setting the torch acetylene valve fully open and turning up the reducing valve until you have just exceeded the pressure which gives a smoke-free acetylene-only flame (pressure is "just higher" so you restrain back slightly on the torch acetylene valve while still having a bit of "headroom").
Now set the preheat flame. Again you must visualise what it is you need - the flame power. And you won't do that until you realise what preheat does. This is about what you are achieving in the stable cutting run. Forget about how to ignite the cut - that is the big mistake. Think about it - you can dwell as long or as short a time on the starting point as you need to get to ignition temperature - so that is totally non-critical on what preheat flame you have on. What the preheat is doing is that on the cutting run it is heating the plate ahead of the oxygen jet to about red-heat. So you are like running a cherry(?)-red-hot spot along the plate at cutting speed. So - visualise the flame power you need to do that for your plate thickness and obtain it on the torch acetylene and preheat-oxygen valves. Now remember this is the flame you will need when the cutting oxygen is flowing - so you must finalise the torch preheat-oxygen valve setting while the cutting oxygen lever is squeezed.
If you think about it, the tip manufacturers are doing something a bit clever - they design the tip so that the pressure of oxygen needed to run the preheat flame is always a bit less than the pressure of the oxygen cutting jet -- otherwise you'd (sometimes) end up with the torch preheat oxygen valve fully open and still not have the ideal oxy-acetylene flame with the "inner cone".
So, in summary
Independently set the oxygen pressure on the cutting jet required. Independently set the acetylene pressure to get the smoke-free acetylene-only flame The preheat-flame oxygen is trailing as a dependent and cannot be "set" - but everything is designed so you can get it by correctly regulating with the torch preheat-oxygen valve.
You will obviously have to build up a map in your mind of what oxygen jet pressure feels right for what plate thickness. And what preheat flame is correct to give that local plate temperature for correct ignition with the cutting oxygen jet. But when you get there (which won't take long) you should get very clean cuts.
For long I-beams and H-columns, I used to be able to flame cut more accurately than you got with sawing - given that the saw is never that level and it's difficult to get the beam truly square-on to the blade - you have straight cuts but usually at some sort of cant to the beam axis! Whereas the oxy-acetylene cut is not machine-smooth but wipes clean with a couple of swipes with a 9inch angle-grinder and is square, as following chalked-on markings which are square to the beam axis in both "cross" axes.
(In statistics and measurement terminology: machine cut -> precise but inaccurate - systematic error. oxy-cut -> imprecise but accurate - no systematic error)
Best wishes
Rich Smith
Reply to
Richard Smith
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"Lenin called them "useful idiots," those people living in liberal democracies who by giving moral and material support to a totalitarian ideology in effect were braiding the rope that would hang them. Why people who enjoyed freedom and prosperity worked passionately to destroy both is a fascinating question, one still with us today. Now the useful idiots can be found in the chorus of appeasement, reflexive anti-Americanism, and sentimental idealism trying to inhibit the necessary responses to another freedom-hating ideology, radical Islam"
Bruce C. Thornton, a professor of Classics at American University of Cal State Fresno
Reply to
Gunner Asch
Ive bought several used Dewalt (yellow/black) power tools over the last few years. Most have failed within a very short time.
Are they all this bad, or did I simply pick used tools that were crap?
Gunner
"Lenin called them "useful idiots," those people living in liberal democracies who by giving moral and material support to a totalitarian ideology in effect were braiding the rope that would hang them. Why people who enjoyed freedom and prosperity worked passionately to destroy both is a fascinating question, one still with us today. Now the useful idiots can be found in the chorus of appeasement, reflexive anti-Americanism, and sentimental idealism trying to inhibit the necessary responses to another freedom-hating ideology, radical Islam"
Bruce C. Thornton, a professor of Classics at American University of Cal State Fresno
Reply to
Gunner Asch
In your case, Gunner, I think it is two things. First, they are used, and therefore worn to an unknown degree when you get them, many might be far along on the failure curve already. Second, you use them probably more and more robustly than a casual occasional user.
Just a thought.
Steve
Reply to
SteveB
True indeed. However Ive bought Milwaukee and Porter Cable and havent lost any yet due to them taking a dump.
Gunner
"Lenin called them "useful idiots," those people living in liberal democracies who by giving moral and material support to a totalitarian ideology in effect were braiding the rope that would hang them. Why people who enjoyed freedom and prosperity worked passionately to destroy both is a fascinating question, one still with us today. Now the useful idiots can be found in the chorus of appeasement, reflexive anti-Americanism, and sentimental idealism trying to inhibit the necessary responses to another freedom-hating ideology, radical Islam"
Bruce C. Thornton, a professor of Classics at American University of Cal State Fresno
Reply to
Gunner Asch
"Gunner Asch" wrote
I know. I have some old tools that look like they will go another twenty years. And some newer ones that look like they barely will go another year.
Steve
Reply to
SteveB
Gunner - everyone
Good links - thanks - visited them and read.
One reason for learning a technique to set up an oxy-acetylene cutting torch which makes no reference to any pressure gauges is that a construction site flame-cutting set with gauges still intact is a rare thing indeed!
Rich S.
Reply to
Richard Smith
Personally..I seldom ever pay attention to the gauges. I just set by flame.
But then..I had bad gauges for years until I scored 18 sets....
Gunner
"Lenin called them "useful idiots," those people living in liberal democracies who by giving moral and material support to a totalitarian ideology in effect were braiding the rope that would hang them. Why people who enjoyed freedom and prosperity worked passionately to destroy both is a fascinating question, one still with us today. Now the useful idiots can be found in the chorus of appeasement, reflexive anti-Americanism, and sentimental idealism trying to inhibit the necessary responses to another freedom-hating ideology, radical Islam"
Bruce C. Thornton, a professor of Classics at American University of Cal State Fresno
Reply to
Gunner Asch

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