Announcement

Collapse
No announcement yet.

#%[email protected] basic oxy-acetylene cutting

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #%[email protected] basic oxy-acetylene cutting

    I just can't get it. Everything I read says a retarded double-amputee lemur can figure out how to cut steel with a oxy-acetylene set and make it look like it was done with a hacksaw in a few minutes. I've had people show me. I've watched people do it for 30-odd years.

    Practice, practice, practice, right? Well apparently I'd make one heckuva oxy-acet welder because that's all I can seem to manage. I can get a cut established but it fills in behind. I'm being told that's because I'm going too fast. Well, I'm going so slow that I'm not even going and the cut still fills in immediately after I burn through.

    This is 3/16" plain old mild steel with what I THINK is a #0 tip (it's not marked in any way). Oxygen is somewhere between 0 and 40PSI (can't figure out what each line on the gauge indicates, there are 7 lines between 0 and 40, but 10 between 40 and 80?!?!). Acetylene is around 5 PSI.

    Everything is as by the book as far as I can tell. My cuts don't look like any of the "wrong" cuts in any of the handbooks I've found. It's just globs.

    Any tips?

  • #2
    Lot of options on this, so heres the list of things to try:

    Start the cut with the tips of the preheat flames just touching the piece. The moment you see a good red from the metal, move th torch over so the blowhole is just off the sheet and hit the jet. Now, move into the cut. Once the cut is established, back the torch off a little more (maybe twice the distance from the end of the tip to the metal as for preheat.)



    Get the chart for you torch and go right on the listed pressures. Guess the pressure assuming the scale is linear. Really the only thing to do. If you can't find a chart, (you don't ay what make and model torch) you may need to play a bit. The acetylene might wan to go DOWN a bit in pressure. Try three PSI. It doesn't take a lot. The oxygen does the work.

    Try different progression speeds...Try varying the speed as you cut. Start slow, and speed up as you go. Look for a regeion with the quality you want. Slow will leave you with a melted top edge, omtimes fusing the material back together, too fast and the cut will drop.

    Make sure the mterial is clean both sides of the cut. Some surface contaminants can cause trouble (like some paints, for example)
    I may not be good looking, but I make up for it with my dazzling lack of personality

    Comment


    • #3
      Might be your torch tip. Have you cleaned it lately. When you hit the trigger you should see a clearly defined oxygen jet and it should extend 4-6 inches beyond the tip. Also with 3/16" material you can angle your torch slightly towards the cut line. Try using a clamped down angle iron straight edge to run your torch against. It'll allow you a better view to follow whats going on and help you get your speed figured out.

      Comment


      • #4
        Originally posted by mkirsch View Post
        I just can't get it. Everything I read says a retarded double-amputee lemur can figure out how to cut steel with a oxy-acetylene set and make it look like it was done with a hacksaw in a few minutes.
        I can make it look kinda like a hack saw cut.....crooked and nowhere near where you wanted to cut.

        I'm in the same boat as you. I put an abrasive blade on my skillsaw for cutting whatever won't fit in the bandsaw, and only use the O/A setup for heating and bending.
        Lincoln SP175
        Craftsman O/A setup
        TA185
        HT30 plasma
        HF 6x4 bandsaw
        Cadillac 1440 lathe
        Tree 2UVR mill
        HF tube roller
        Bead roller
        Pro-Tools 105 bender

        Comment


        • #5
          I'll 2nd what Old Spark stated about using another piece for a guide......and angling the torch into the cut so it is blowing/pushing the molten metal into the metal to be cut and not the open void that you just cut....not a big tilt just a little....good luck,
          Mike
          George W. Bush saving your butt whether you like it or not!
          If there must be trouble let it be in my day, that my child may have peace.
          Thomas Paine
          Fear is temporary, regret is forever
          HH210 w S.G.
          Victor/Uniweld O/P
          Dewalt Chop Saw

          Comment


          • #6
            It's hard enought to learn without the added handicaps you have. You need to know what you're using, not guess at it!

            What brand is the torch? Get a new tip for it so you know what size it is. Set the O² to 40 PSI! At least you'll know where it is set. One symptom of the cut filling in is too little cutting oxygen. In 3/16 stock with everything right, you should be moving about 18" per minute.

            Hank
            ...from the Gadget Garage
            MM 210 w/3035, BWE
            HH 210 w/DP 3035
            TA185TSW
            Victor O/A "J" series, SuperRange
            Avatar courtesy of Bob Sigmon...

            Comment


            • #7
              Originally posted by mkirsch View Post
              I just can't get it. Everything I read says a retarded double-amputee lemur can figure out how to cut steel with a oxy-acetylene set and make it look like it was done with a hacksaw in a few minutes. I've had people show me. I've watched people do it for 30-odd years.
              We have an unwritten rule on this site, that no matter how frustrated you get by not being able to master a welding/cutting procedure, you do not denigrate lemurs.

              Comment


              • #8
                Originally posted by Goodhand View Post
                We have an unwritten rule on this site, that no matter how frustrated you get by not being able to master a welding/cutting procedure, you do not denigrate lemurs.
                Hey Goodhand, I saw your car in town today...



                And I'm not so sure, those wascally lemurs can be a dangerous sort!

                Trailblazer 302 * Millermatic 212 * Syncrowave 180SD * X-Treme 12VS Feeder * Spoolmate 3035
                Thermal Dynamics Cutmaster 52 Plasma * Lincoln 175 MIG

                Victor Superrange II * Victor Journeyman

                Hobart HH 125EZ


                Comment


                • #9
                  I thought it was quite denigrating to be told that a retarded double-amputee lemur could easily perform a task that I seem incapable of!

                  Comment


                  • #10
                    The problem might be in your torch. It might need the blow valve seat replaced/repaired.

                    I had that problem with my old torch. Worked well for years but then all sudden started acting up. I coulnd't cut anything. I couldn't regulate the OX flow with the lever. Took it to the LWS for a repair and they told me that the valve seat was shot. Somehow. But when you're that old, things tend to fall apart for no apparent reason. Cost - $52 and it's good as new.

                    RoGrrr
                    I'm not a professional BUT I "do try this at home".

                    I ask for help when I THINK I need it.

                    http://www.youtube.com/watch?v=-TC2xTCb_GU

                    Comment


                    • #11
                      I know I had a lot of aggravation with A/O cutting, until I got the distance from tip to metal figured out. Once I hit that, it was like night and day.

                      Mark

                      Comment


                      • #12
                        Thats what the oxygen is for, pull the trigger and it should blow the moltent metal out, thast wha tI do atleast or what I understand what yours supposed to do, once molten metal starts dripping off where you begin to cut press the oxyen trigger and it should blow it all out. thats my take on what yorue doing possibly?

                        Comment


                        • #13
                          Likely we got the preheat too hot or too much 02 on the heat. 20# of 02 is plenty, just enough to burn the material thru. You are not blowing it out, you are burning it thru.
                          http://www.facebook.com/cary.urka.urkafarms

                          Comment


                          • #14
                            Originally posted by RossTheWeldor View Post
                            Thats what the oxygen is for, pull the trigger and it should blow the moltent metal out, thast wha tI do atleast or what I understand what yours supposed to do, once molten metal starts dripping off where you begin to cut press the oxyen trigger and it should blow it all out. thats my take on what yorue doing possibly?
                            It may seem like that's what's goin' on, but it really ain't!

                            Oxy-fuel cutting is a misnomer. You don't "cut" anything. What you do is set the steel on fire. It burns in the presence of the oxygen you are pouring into the fireplace! The force of the stream of oxygen tends to blow the products of combustion (the slag) away. Still, the actual physical phenomenon that is taking place is plain old combustion!

                            You need to understand these seemingly uninteresting things in order to really get a grip on what's happening with an O/A "cutting" torch!

                            Hank
                            ...from the Gadget Garage
                            MM 210 w/3035, BWE
                            HH 210 w/DP 3035
                            TA185TSW
                            Victor O/A "J" series, SuperRange
                            Avatar courtesy of Bob Sigmon...

                            Comment


                            • #15
                              Yup, if it was just blowing the molten metal out of the cut, you'd use cheap compressor air, not expensive oxygen!!!

                              Nothing I'm doing is making any difference. Faster, slower. Closer, further away. More oxygen, less oxygen. More acetylene, less acetylene. Bigger flame, smaller flame. Angled into cut, angled away from cut. No matter what I do, molten steel flows into the cut behind the torch.

                              Comment

                              Working...
                              X