Announcement

Collapse
No announcement yet.

Arc Blow

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

  • Arc Blow

    I was working with a friend on 1" plate, 22 1/2 bevel, for a 45 joint, 3G vert up,1/4 gap, with 1/4 " backer strip, he has to use 115 to 130 amps DC+, with 7018 H4 rods. He runs in to arc blow frequently. We went to the lowest 115 amp setting, changed rod positioning, held tight to joint, wrapped cables to try offsetting magnetic field, reposition ground to begining, and end of joint, heavy tacks, and a couple other things. As is normal, it is normally just on the root, 2nd, and sometimes the 3rd pass, and in the upper 3rd of the plate. He been pointing rod up, about 20 to 30 degrees, but has also tried going straight in, when blow starts. All equipment connections good. I have tried things that helped me, but need other ideas. Thanks

  • #2
    Why does he have to use DC? Try AC.
    Oxy/Ac Large Tanks
    Miller Swinger AC 180 (SOLD)
    Miller Syncrowave 250DX Runner with Pulser

    Comment


    • #3
      First, why does he use DC? Because its what he is sposed to be using. Look at an SA200, stick pipe welding machine, no AC to be found on it. This is out of position work, DC is so far superior. Only time my shop machine has ever been set to AC is for some nickle.
      I have to agree with Ironhead, this isn't the kind of arc blow everyone reads about in threads which for the most part is very rare and minor, easily corrected with tacks. I would say rod angle issues too, also have had old rods burn off to the side

      Comment


      • #4
        follow uo

        He is practicing, as per the wps he has, and DC+ is the polarity. What angle, do think he should adjust to, once the arc blow starts to show up?

        Comment


        • #5
          Ya could just stop welding. grind a tish and start back up.

          Comment


          • #6
            rod angle, old rods, clean rods, heat the plate, and maybe a little grinding are the only things i can think of to cure the problem that i know of. some times also i have found that when the cables are coiled around each other at all arc blow can happen but other than that i dont know.
            trail blazer 302
            hypertherm plasma
            millermatic 251
            high feq. arc starter
            suit case (extreme 12vs)
            o/a torches
            way to many other tools to list

            Comment


            • #7
              arc blow

              For our discussion here arc blow is simply magnetism building up in the base metal and causing a reaction in the arc. Any electrical circuit will have some electromagnetic field build up. Historically we have wrapped the part a couple of times with the work lead to counter act the field, heating the part also works where it is ok to heat the metal that high, there is a point where the metal gets hot enough that it becomes no responsive to magnetism.

              Most often what I have found is that the cables are all coiled up, out on the job the cables are stretched out but just running practice beads isn't worth the effort to string out your cables and then pick them back up. Sometimes I have even found the cables coiled up and sitting on top of the welder or still hanging on a steel holder. Once you have a copper cable coiled up and them it has steel running through it you have a transformer. 25 or 30 feet of cable coiled up also provieds a great way to magnetize tools when there is current flowing.

              So if all else fails think of the basics of magnetism, the larger the coil the stronger the field, so stretch out the coil. Also remember to weld toward your work clamp.

              Another idea that I picked up from one of our foreign engineers Tiejin is to loop the cable and fold it back on itself. See the picture attached.
              Attached Files

              Comment


              • #8
                I dont think for practice the ultimate condition of the rods are of much importance, when we say old rods I for one am talking old where they been laying in the same place, maybe years? As for rod angle it is a natural tendency to increase it as one goes up, you twist your wrist up instead of moving your arm up perpendicular to the work. It takes discipline, 0 to 10 degrees at most, almost straight and square. I still tend to do it.

                Comment


                • #9
                  No, that is what makes it alternate.

                  Good thread, thanks.
                  Weekend wannab racer with some welders.

                  Comment


                  • #10
                    Originally posted by Iron Head
                    That is very interesting!


                    But wouldn’t that slow down the current?
                    only if you kink it like a garden hose

                    The purpose is to control the inductance in the line, where the EMF is expanding and collapsing. Controlling the magetic field is going to be key to arc blow.

                    Comment


                    • #11
                      thats why i dont use reels on my truck i lat them in the back almost the same a the method above and had no problems with arc blow or over heating of cables.
                      trail blazer 302
                      hypertherm plasma
                      millermatic 251
                      high feq. arc starter
                      suit case (extreme 12vs)
                      o/a torches
                      way to many other tools to list

                      Comment


                      • #12
                        Originally posted by arc View Post
                        thats why i dont use reels on my truck i lat them in the back almost the same a the method above and had no problems with arc blow or over heating of cables.
                        Hey do you happen to have any pictures of your truck or a link to pictures you've posted here before?

                        Lots of interesting ways to deal with Arc Blow in this thread, great information!
                        at home:
                        2012 325 Trailblazer EFI with Excel power
                        2007 302 Trailblazer with the Robin SOLD
                        2008 Suitcase 12RC
                        Spoolmatic 30A
                        WC-24
                        2009 Dynasty 200DX
                        2000 XMT 304
                        2008 Thermal Dynamics Cutmaster 52
                        Sold:MM130XP
                        Sold:MM 251
                        Sold:CST 280

                        at work:
                        Invision 350MP
                        Dynasty 350
                        Millermatic 350P
                        Retired:Shopmaster 300 with a HF-251

                        Comment


                        • #13
                          all my pics of my truck were on my old laptop. but i will try to get some more pics of the cables. but im currently heading down to australia for work for about a year. if u want to not use reels just loop them in sepately in a figure 8 configuration on each side of the box. have seen some guys hang them like this too but i had room at the back so i laid them down. the old out of site out of mind trick.
                          trail blazer 302
                          hypertherm plasma
                          millermatic 251
                          high feq. arc starter
                          suit case (extreme 12vs)
                          o/a torches
                          way to many other tools to list

                          Comment


                          • #14
                            Good to know Arc.
                            I always like lookin at guys rigs, you can learn something from each one you see. Everyone has their own preferences and needs!
                            at home:
                            2012 325 Trailblazer EFI with Excel power
                            2007 302 Trailblazer with the Robin SOLD
                            2008 Suitcase 12RC
                            Spoolmatic 30A
                            WC-24
                            2009 Dynasty 200DX
                            2000 XMT 304
                            2008 Thermal Dynamics Cutmaster 52
                            Sold:MM130XP
                            Sold:MM 251
                            Sold:CST 280

                            at work:
                            Invision 350MP
                            Dynasty 350
                            Millermatic 350P
                            Retired:Shopmaster 300 with a HF-251

                            Comment


                            • #15
                              no prob iv have figured that out after replaing 400 feet of burnt out cable works well and really doesnt take any more room that reels. just sucks when they freeze to the bottom of the box.
                              trail blazer 302
                              hypertherm plasma
                              millermatic 251
                              high feq. arc starter
                              suit case (extreme 12vs)
                              o/a torches
                              way to many other tools to list

                              Comment

                              Working...
                              X