Announcement

Collapse
No announcement yet.

Suggestions for cutting 2" thick steel with .39% carbon content

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

  • Suggestions for cutting 2" thick steel with .39% carbon content

    Hello Weld Talk Members,

    I'm brand new to the site and very anxious to learn all I can from you guys. I will be taking a vocational welding class later this summer and will probably learn the answer there but this question just cant wait. I have this piece of 2" thick steel, its actually from a forklift fork, the steel type is 15B35H, a medium carbon steel with a small amount of Boron with ~206HB.

    My set up:
    Harris Calorific 63-2 handle
    73-1 cutting attachment
    6290-3 tip
    3/8" line
    Harris 96-100 2 stage regulators
    Gas Pressures: O2 at 45 and Acetylene at 6

    I have cut steel up to 1" before but never 2" so I understand there is most likely a learning curve but as hard as i try to maintain the correct distance from the steel, take my time and move slowly but not too slowly, use a guide..........no matter what I do I get the ugliest cut with slag everywhere, deep gouges.....yuck! Its just plain nasty. I keep reading about people cutting thick steel and ending up with a surface that rivals machining!? Mine looks like a an animal with very strong teeth chewed it apart ( I could attach a pic if necessary but oh man Im embarrassed)
    I stand ready to be corrected, guided, educated, etc. What I received on my last attempt to learn from experienced guys however was "go do your own learning and then come with questions". Ok, I'm all about trying very hard to figure things out on my own before I ask for help but whats wrong with asking someone more experienced than you how they do it? Meh...I digress.
    I was looking at track torches at one point because I saw several videos of guys using them to cut thick steel and the resulting finish was amazing but Id rather not drop $500+ when 99% of the material I need to cut on a regular basis is only 6" x 2". There must be a better way, I know I must be missing something.

    Thank you in advance for your help, I sincerely appreciate it and look forward to continuing to learn as I go, hopefully getting to the point where I can pass some of this on to my two boys someday.

    Bob
    Last edited by Blue Collar Bob; 03-04-2018, 11:03 AM. Reason: Added hardness, not sure if that has a handle in my troubles.

  • #2
    Run the O2 pressure up to about 80lbs.

    Comment


    • #3
      Thank you, that will be an easy experiment to try. Can I also ask you if the difference between torch tips 6290-1, 2, and 3 is just the hole size or is the shape/length different as well. I had a friend suggest opening up the oxygen hole a little but then I read that it can effect the way the O2 stream comes out, it could cause it to flow in a weird direction or something. Is the practice of opening/changing preheat and O2 hole size acceptable? My thought would be to just purchase the next size up but I guess in a pinch it would be worth a try.

      Thanks again, I will give that a shot in the next few minutes.
      Bob

      Comment


      • #4
        Originally posted by Blue Collar Bob View Post
        Thank you, that will be an easy experiment to try. Can I also ask you if the difference between torch tips 6290-1, 2, and 3 is just the hole size or is the shape/length different as well. I had a friend suggest opening up the oxygen hole a little but then I read that it can effect the way the O2 stream comes out, it could cause it to flow in a weird direction or something. Is the practice of opening/changing preheat and O2 hole size acceptable? My thought would be to just purchase the next size up but I guess in a pinch it would be worth a try.

        Thanks again, I will give that a shot in the next few minutes.
        Bob
        Bob

        1) Do not ruin your tips with your "friend's" advice! This is not acceptable!

        2) Do NOT use 80 psi to cut 2" steel with the appropriate tip. A Victor #3 would do the job with about 40-45 psi with about 7 psi of acetylene. You will waste much oxygen, and get a poor cut with that pressure. Also, you will likely empty your oxygen bottle in less than an hour at that 80psi.

        3) Go to the Harris site and down-load their pressure-thickness chart to be sure, but I am sure that it will be similar.
        Last edited by Northweldor; 03-04-2018, 12:54 PM.

        Comment


        • #5
          Its probably pretty common to find conflicting advice on sites like this with so many helpful people. I will refer to the Harris 6290 tip chart for 2" steel and see what it says. I see that there are different preheat and cutting pressure for 3 hose systems but on two hose systems like mine it says preheat and cutting pressure are the same. Can you shed some light on that and if you agree or not. Also, we only know what we have been taught from those before us so I know my Dad showed me the way his Dad showed him and so on, it doesnt mean however that it was entirely correct and Im pretty sure they were not cutting 2" steel. With that said here is what I do: 1.) Light the gas and open it wide open because i want the 6lb pressure the regulator is set at. 2.) Then I slowly add the O2 in until the flame is almost colorless, 3) depress the cutting handle and tune the O2 until the center looks clean 4.) release the handle and proceed to preheat the edge of my block before depressing the handle again and beginning my cut. note: my pressure on the O2 regulator is 50 and the lower valve on my handle is wide open, all adjustments take place at the valve near the head. This is a 3 tube cutting attachment if that matters?
          What Im not sure about is if the regulator is set to 50, unless I open the top valve fully I wont be getting 50 will I? If that was the case then when I depressed the handle the top valve wouldn't impact the O2 flow but it does? How the heck do I get a true 50psi without opening the top valve all the way to allow full flow? Now Im just confusing myself! I know.....take the class! I wish my Dad was here to learn this with me, it sucks going it alone. Well, any help understanding the initial set up to achieve the recommended settings (attached) would be greatly appreciated.

          Bob

          Comment


          • #6
            Your post of the sizing chart really does give most of the leading particulars needed for your questions. You know the tip you are utilizing which is correct for the job. You have the reference pressures from the chart available. What I suspect is lacking is experience citing lack of correct preheat into the base material prior to attempting to cutting. With thick base material to cut you need to dwell on the edge of the plate for several seconds in one spot till this spot almost falls away from becoming liquid. At the time you depress the cutting oxygen lever on the torch handle, the oxygen stream should pierce all the way through the thickness prior to moving the torch. If it explodes, it wasn't preheated enough through. Once a clean piercing is achieved, a slow and deliberate pace of movement of the torch assembly will yield the best cut. This takes practice and is best started out on thinner materials.

            Free hand torch cutting can be smooth and approach a machine torch in comparison but that takes a lot of practice.

            I can't stress enough how important practice is.
            Thanks for reading/listening.

            Antique Hobart Engine Drive Lover X5

            Comment


            • #7
              Even when I was at my best, I would always use the bug to cut heavy steel...the cleanup is minimal, and you get the best cut from the machine, and you get it in one pass.. In the picture I was using the bug to spray arc 2" to 5." steel. I used it for cutting the chamfers, too. It didn't work as well as I had hope, but I got a couple of decent passes with it. I only add this to show the versatility of using a machine torch setup. We called it a "bug" which is actually a brand name for a machine tractor torch. Bugg company makes them, but this one is a Victor. I loved it! Well worth the money!

              Comment


              • #8
                Well I must say you guys are really kind in your responses, I completely understand the need for practice and I will continue to do so In thinner material every chance I get. Did you guys understand my comprehension issue regarding pressures and when they are actually realized? It is correct to leave the bottom O2 valve wide open, top closed? then once the fuel is ignited slowly add O2 in via the top valve to achieve a neutral flame? The only trouble I have with getting my brain wrapped around that is if the regulator is set to say 45psi then I imagine 45psi exiting the 3/8" hose *only* if no valve were restricting it. How can I achieve the 45psi cutting O2 pressure, which I assume is with the handle depressed fully, if the top valve is anything other than wide open? I feel like I want to take a pressure reading at the tip with the lever depressed fully and make sure its 45psi then add some fuel in, light it, and adjust the fuel until I achieve neutral flame. Does that make sense?
                Im making this way more complicated that it needs to be aren't I ? oh man my head hurts!
                I just want 45psi at the tip when I depress the lever thats all! lol.
                Im also going to pick up a #3 tip because Im starting to thinks this has been messed with or its just old.
                Im really not trying to frustrate you guys on my first day, you must remember back when right? the green days.....hello?

                I like the BUG, I looked at track torches for a long time and struggle to justify the investment but if I am going to be cutting dozens of these 2" blocks it may be the best be because I could line up the material and set the BUG free. Aside from that though I would really like to have a good understanding on setting the torch pressure to achieve exactly whats recommended for the tip when cutting, if I can achieve that it will be a great first day on WeldTalk!

                Thank you all again.

                Bob

                Comment


                • #9
                  Originally posted by Blue Collar Bob View Post
                  Its probably pretty common to find conflicting advice on sites like this with so many helpful people. I will refer to the Harris 6290 tip chart for 2" steel and see what it says. I see that there are different preheat and cutting pressure for 3 hose systems but on two hose systems like mine it says preheat and cutting pressure are the same. Can you shed some light on that and if you agree or not. Also, we only know what we have been taught from those before us so I know my Dad showed me the way his Dad showed him and so on, it doesnt mean however that it was entirely correct and Im pretty sure they were not cutting 2" steel. With that said here is what I do: 1.) Light the gas and open it wide open because i want the 6lb pressure the regulator is set at. 2.) Then I slowly add the O2 in until the flame is almost colorless, 3) depress the cutting handle and tune the O2 until the center looks clean 4.) release the handle and proceed to preheat the edge of my block before depressing the handle again and beginning my cut. note: my pressure on the O2 regulator is 50 and the lower valve on my handle is wide open, all adjustments take place at the valve near the head. This is a 3 tube cutting attachment if that matters?
                  What Im not sure about is if the regulator is set to 50, unless I open the top valve fully I wont be getting 50 will I? If that was the case then when I depressed the handle the top valve wouldn't impact the O2 flow but it does? How the heck do I get a true 50psi without opening the top valve all the way to allow full flow? Now Im just confusing myself! I know.....take the class! I wish my Dad was here to learn this with me, it sucks going it alone. Well, any help understanding the initial set up to achieve the recommended settings (attached) would be greatly appreciated.

                  Bob
                  Procedure for setting the torch:'

                  1 Set acetylene regulator to 6 psi. Open acet, torch valve and when lit, open at least 3 half turns. Then adjust acetylene regulator so the flame is blowing away from the tip about 3/8". Turn acet. torch valve down until the flame returns to the tip.

                  2. With the oxygen regulator set at 50psi, gradually add oxygen and acetylene until you have both valves wide open (3 half turns)

                  3, Adjust your pre-heat oxygen (Valve at mid torch) to get a neutral flame, then press cutting lever and re-adjust to neutral. You are ready to cut.

                  (When you have a neutral flame, the feathers on the preheat flames will just merge with the bright cones).

                  Cutting:

                  1. ( On 2" material, cutting from edge to edge). Hold the preheats still on one edge until you see the corner begin to glow red, then depress cutting lever and wait till the cut gets to the bottom of the metal, before you start to move along the cut, and then, move only fast enough that the spark stream is coming almost straight out of the bottom of the metal. If it is going opposite to the direction of travel, slow down, and if you lose the cut or the top edges are melting, speed up.

                  Do not do this anywhere except an area that has been cleared of flammables for 40' in all directions, fire extinguisher available, and fire-watcher. Also, do not wear your runners!

                  Re: question on pressure, and the preheat valve: the high pressure oxygen is controlled by the cutting lever only. It by-passes the preheat oxygen valve.

                  Forgot to mention that preheats should be kept within 1/4 " of metal surface, but not touching.
                  Last edited by Northweldor; 03-05-2018, 06:58 AM.

                  Comment


                  • #10
                    Good point, NW...don't wear tennis shoes...I won't ask how you know this...

                    Comment


                    • #11
                      Cut-O-Matic is the brand of mine and it uses a "Victor" torch. It was given to me 100% operational along with 12' of track by a friend whom I used to work with. They replaced it with a plasma table and this sat unused on their shelves about 20 years prior to my asking for it. You never know what is out there till you ask sometimes. I can't hand cut anything as smooth and linear as this thing will so definitely worth looking into acquiring one if doing a lot of cutting.

                      Another useful tool down the road is a "Heck" bevel mill. I have a model "850" and it sure saves the back on beveling structural material to get good penetration welds.

                      Thanks for reading/listening.

                      Antique Hobart Engine Drive Lover X5

                      Comment


                      • #12
                        You guys are the best, I hope someday I can contribute to helping a newbie along the way, seriously its made all the difference and thank you all.

                        Comment


                        • #13
                          Originally posted by Rocky D View Post
                          Good point, NW...don't wear tennis shoes...I won't ask how you know this...
                          You're right: I learned the hard way, and still have the scar, 65 years later!

                          Comment


                          • #14
                            You got to be careful no matter what you're doing with a torch. I still have the scars from cutting the exhaust studs off of a 69 Cadillac while on a lift and a 3/4" slag ball rolling into the crook of my upper and forearm, melting into the skin. That was 45 years and a couple of months ago. Had to dig it out by hand as it wouldn't shake loose all the while burning my shirt and recessing into the skin.

                            Sorta like frying bacon naked.
                            Thanks for reading/listening.

                            Antique Hobart Engine Drive Lover X5

                            Comment


                            • #15
                              This gent has a few interesting videos using a track torch cutting 3.5" thick steel:

                              https://www.youtube.com/watch?v=F2ZRbZhehwI
                              Thanks for reading/listening.

                              Antique Hobart Engine Drive Lover X5

                              Comment

                              Working...
                              X